CN113894379A - Constant temperature circuit for electric soldering iron and electric soldering iron - Google Patents
Constant temperature circuit for electric soldering iron and electric soldering iron Download PDFInfo
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- CN113894379A CN113894379A CN202111367511.3A CN202111367511A CN113894379A CN 113894379 A CN113894379 A CN 113894379A CN 202111367511 A CN202111367511 A CN 202111367511A CN 113894379 A CN113894379 A CN 113894379A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K3/00—Tools, devices, or special appurtenances for soldering, e.g. brazing, or unsoldering, not specially adapted for particular methods
- B23K3/02—Soldering irons; Bits
- B23K3/03—Soldering irons; Bits electrically heated
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K3/00—Tools, devices, or special appurtenances for soldering, e.g. brazing, or unsoldering, not specially adapted for particular methods
- B23K3/08—Auxiliary devices therefor
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- Control Of Resistance Heating (AREA)
Abstract
The application discloses a constant temperature circuit and electric iron for electric iron, including first power supply circuit, switch circuit, heating circuit, sampling circuit, default voltage circuit and comparison circuit. Wherein, first power supply circuit is used for converting an alternating current into first direct current, and switch circuit connects first power supply circuit and heating circuit when being used for switching on, and heating circuit is used for the electric energy conversion heat energy with first direct current, and sampling circuit is used for the voltage sampling to the flatiron core that generates heat, and preset voltage circuit is used for exporting preset voltage signal, and comparison circuit is used for comparing sampling voltage signal and preset voltage signal to according to the result control switch circuit switch on or break off of comparison. This application generates heat the principle that the resistance value that the core corresponds along with the temperature variation also changes according to the flatiron, generates heat the voltage of core to the flatiron and samples to according to the comparative result control switch circuit of sampling voltage signal and presetting voltage signal switch on or break off, and then realize the thermostatic control of electric iron.
Description
Technical Field
The application relates to the technical field of electric tools, in particular to a constant temperature circuit for an electric soldering iron and the electric soldering iron.
Background
The electric soldering iron is a necessary tool for electronic manufacturing and electric appliance maintenance, is mainly used for welding machine elements and conducting wires, and along with the development of times and science and technology, more and more electronic products enter people's lives, and the electric soldering iron also becomes a household stock tool. Therefore, the production cost of the electric soldering iron is reduced while the performance of the electric soldering iron is improved, and the electric soldering iron becomes a main research direction of the electric soldering iron. Electric soldering iron products are currently classified into non-temperature-control electric soldering irons, temperature-adjustable electric soldering irons and temperature-adjustable electric soldering irons on the market. For example, the electric iron can be divided into an internal heating type electric iron and an external heating type electric iron according to a heating mode. Wherein, the internal heating type soldering iron has two heating cores which are two cores and four cores which are provided with temperature induction wires. The four-core soldering iron with the temperature induction wire has good performance, but needs to be matched with the MCU control circuit, so the cost is much higher than that of the two-core heating core, and the price of the product is not very suitable for common users. However, the common two-core soldering iron usually has no temperature sensing wire, so that the electric soldering iron cannot work at a constant temperature. The two-core heating core soldering iron commonly available on the market is non-temperature-control soldering iron or temperature-adjustable soldering iron. Although the temperature of the soldering iron can be changed, the temperature of the soldering iron can not be monitored immediately, and the working temperature of the soldering iron can not be guaranteed to be constant, so that the difference between the nominal working temperature and the actual working temperature of the soldering iron is large, and the difference can reach hundreds of degrees. How to reduce the difference between the actual working temperature and the nominal working temperature of the electric soldering iron is the main direction for manufacturers to research and develop the electric soldering iron.
Disclosure of Invention
The technical problem that this application will be solved is how to reduce the difference of the actual operating temperature and the nominal operating temperature of electric iron.
According to a first aspect, a constant temperature circuit for an electric soldering iron comprises a first power circuit, a switch circuit, a heating circuit, a sampling circuit, a preset voltage circuit and a comparison circuit;
the first power supply circuit comprises a first alternating current connection end and a first switch connection end; the first alternating current connecting end is used for being connected with a live wire of alternating current, and the first switch connecting end is connected with the switch circuit; the first power supply circuit is used for converting the alternating current into a first direct current to the switch circuit;
the switch circuit comprises a first connecting end, a second connecting end and a third connecting end; the first connecting end of the switch circuit is connected with the first switch connecting end, the second connecting end of the switch circuit is connected with the comparison circuit, and the third connecting end of the switch circuit is connected with the heating circuit; when the switch circuit is conducted, connecting the first power supply circuit and the heating circuit to output the first direct current output by the first power supply circuit to the heating circuit; when the switch circuit is disconnected, disconnecting the first power supply circuit and the heating circuit;
the heating circuit comprises a second alternating current connecting end, a second switch connecting end, a sampling circuit connecting end and a soldering iron heating core; the second alternating current connecting end is used for being connected with a zero line of alternating current, the second switch connecting end is connected with the switch circuit, and the sampling circuit connecting end is connected with the sampling circuit; the heating circuit is used for converting the first direct current into heat energy through the soldering iron heating core;
the sampling circuit comprises a first connecting end and a second connecting end, the first connecting end of the sampling circuit is connected with the connecting end of the sampling circuit, and the second connecting end of the sampling circuit is connected with the comparison circuit; the sampling circuit is used for sampling the voltage of one connecting end of the heating core of the soldering iron so as to obtain a sampling voltage signal and sending the sampling voltage signal to the comparison circuit;
the preset voltage circuit comprises a first connecting end, and the first connecting end of the preset voltage circuit is connected with the comparison circuit; the preset voltage circuit is used for outputting a preset voltage signal to the comparison circuit;
the comparison circuit comprises a first connection end, a second connection end and a third connection end, the first connection end of the comparison circuit is connected with the second connection end of the switch circuit, the second connection end of the comparison circuit is connected with the second connection end of the sampling circuit, and the third connection end of the comparison circuit is connected with the first connection end of the preset voltage circuit; the comparison circuit is used for outputting a first switching signal when the value of the sampling voltage signal is not greater than the value of the preset voltage signal, and the switching circuit responds to the first switching signal to be conducted; the comparison circuit is further used for outputting a second switching signal when the value of the sampling voltage signal is larger than the value of the preset voltage signal, and the switching circuit is switched off in response to the second switching signal.
In one embodiment, the constant temperature circuit further comprises a second power circuit, wherein the second power circuit comprises a first connection end, a second connection end and a third connection end; the first connecting end of the second power supply circuit is used for being connected with the live wire of the alternating current, the second power supply circuit is used for converting the alternating current into a second direct current, and the second direct current is output through the second connecting end and the third connecting end of the second power supply circuit; the preset voltage circuit further comprises a second connecting end, and the second connecting end of the second power supply circuit is connected with the second connecting end of the preset voltage circuit so as to be used for supplying power to the preset voltage circuit; the comparison circuit further comprises a fourth connection end, and the third connection end of the second power supply circuit is connected with the fourth connection end of the comparison circuit so as to provide power for the comparison circuit.
In one embodiment, the first power circuit further comprises a diode D11, an anode of the diode D11 is connected to the first ac connection terminal, and a cathode of the diode D11 is connected to the first switch connection terminal;
and/or one connecting end of the soldering iron heating core is connected with the second switch connecting end, and the other connecting end of the soldering iron heating core is connected with the second alternating current connecting end; the second alternating current connection end is grounded; the second switch connecting end is electrically connected with the sampling circuit connecting end.
In one embodiment, the switching circuit further comprises a thyristor D31, a diode D32, and a resistor R31;
the positive connecting end of the controlled silicon D31 is connected with the first connecting end of the switch circuit, the negative connecting end of the controlled silicon D31 is connected with the third connecting end of the switch circuit, and the control end of the controlled silicon D31 is connected with the negative electrode of the diode D32;
one end of the resistor R31 is connected with the anode of the diode D32, and the other end is connected with the second connection end of the switch circuit.
In one embodiment, the switch circuit further includes a light emitting diode D33, and the light emitting diode D33 is connected in series between the diode D32 and the resistor R31.
IN one embodiment, the comparison circuit further comprises a comparator chip U1, the comparator chip U1 comprises a pin-IN, a pin + IN, a pin V-, a pin V + and a pin OUT, the pin OUT of the comparator chip U1 is connected with a first connection end of the comparison circuit, the pin-IN of the comparator chip U1 is connected with a second connection end of the comparison circuit, and the pin + IN of the comparator chip U1 is connected with a third connection end of the comparison circuit; pin V-of comparator chip U1 is grounded; pin V + of comparator chip U1 is connected to the fourth connection of the comparator circuit.
In one embodiment, the preset voltage circuit further includes a resistor R61, a resistor R62, a resistor R63, a resistor R64, a resistor R65, a resistor R66, a resistor R67, and a resistor R68;
one end of the resistor R61 is connected with the second connecting end of the preset voltage circuit, and the other end of the resistor R61 is connected with the first connecting end of the preset voltage circuit;
one end of the resistor R62 is connected with the first connection end of the preset voltage circuit, and the other end of the resistor R62 is grounded;
the resistor R63 and the resistor R64 are connected in series, one end of the resistor R63 and the resistor R64 after being connected in series is connected with the first connecting end of the preset voltage circuit, and the other end of the resistor R64 after being connected in series is grounded;
the resistor R65 and the resistor R66 are connected in series, one end of the resistor R65 and the resistor R66 after being connected in series is connected with the first connecting end of the preset voltage circuit, and the other end of the resistor R66 after being connected in series is grounded;
the resistor R67 and the resistor R68 are connected in series, one end of the series connection is connected with the first connection end of the preset voltage circuit, and the other end of the series connection is grounded.
In one embodiment, the preset voltage circuit further includes a sliding rheostat R71, a resistor R72, a sliding rheostat R73, a resistor R74 and a resistor R75; the sliding rheostat R71 and the sliding rheostat R73 respectively comprise a first fixed end, a second fixed end and a first sliding end;
the resistor R74 and the resistor R75 are connected in parallel, one end of the parallel connection is connected with the second fixed end of the slide rheostat R73, and the other end of the parallel connection is grounded;
the first sliding end of the sliding rheostat R73 is connected with the first connection end of the preset voltage circuit,
one end of the resistor R72 is connected with the first fixed end of the slide rheostat R73, and the other end is connected with the second fixed end of the slide rheostat R71;
the first fixed end of the slide rheostat R71 is connected with the second connecting end of the preset voltage circuit, and the first sliding end of the slide rheostat R71 is connected with the first fixed end of the slide rheostat R71.
In one embodiment, the second power supply circuit further includes a fourth connection terminal, and the second power supply circuit is further configured to output the second direct current to the sampling circuit through the fourth connection terminal of the second power supply circuit to supply power to the sampling circuit;
the sampling circuit further comprises a third connecting end, a triode Q41, a resistor R41 and a resistor R42; the third connecting end of the sampling circuit is connected with the fourth connecting end of the second power supply circuit;
one end of the resistor R41 is connected with the third connecting end of the sampling circuit, and the other end of the resistor R41 is connected with the control electrode of the triode Q41;
a first pole of the triode Q41 is connected with the first connecting end of the sampling circuit, and a second pole of the triode Q41 is connected with the second connecting end of the sampling circuit;
one end of the resistor R41 is connected with the second connecting end of the sampling circuit, and the other end is grounded.
According to a second aspect, an electric soldering iron comprises the thermostatic circuit of the first aspect.
According to the embodiment, the constant temperature circuit for the electric soldering iron comprises a first power supply circuit, a switch circuit, a heating circuit, a sampling circuit, a preset voltage circuit and a comparison circuit. Wherein, first power supply circuit is used for converting an alternating current into first direct current, and switch circuit connects first power supply circuit and heating circuit when being used for switching on, and heating circuit is used for the electric energy conversion heat energy with first direct current, and sampling circuit is used for the voltage sampling to the flatiron core that generates heat, and preset voltage circuit is used for exporting preset voltage signal, and comparison circuit is used for comparing sampling voltage signal and preset voltage signal to according to the result control switch circuit switch on or break off of comparison. According to the principle that the resistance value of the heating core of the soldering iron corresponding to the temperature change also changes, the voltage value of the heating core of the soldering iron is sampled, and the switching circuit is controlled to be switched on or switched off according to the comparison result of the sampling voltage signal and the preset voltage signal, so that the constant temperature control of the soldering iron is realized. The circuit of the constant temperature circuit is simple in structure, low in cost and high in temperature regulation response speed, and the difference between the actual working temperature and the nominal working temperature of the electric soldering iron is greatly reduced.
Drawings
FIG. 1 is a functional block diagram of a thermostat circuit in one embodiment;
FIG. 2 is a schematic diagram of the circuit connections of the thermostat circuit in one embodiment;
FIG. 3 is a schematic diagram of a circuit connection of a preset voltage circuit in another embodiment;
FIG. 4 is a schematic diagram of the circuit connection of a second power circuit according to an embodiment;
FIG. 5 is a schematic circuit diagram of a second power circuit according to another embodiment;
FIG. 6 is a schematic diagram of the operation of a thermostat circuit in one embodiment;
FIG. 7 is a schematic diagram of a circuit board of an electric soldering iron according to an embodiment.
Detailed Description
The present application will be described in further detail below with reference to the accompanying drawings by way of specific embodiments. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.
Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.
The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings).
The embodiment of the application provides a constant temperature circuit, which is characterized in that according to the principle that the resistance value of a heating core of an iron changes along with the temperature change, the voltage value of the heating core of the iron is sampled, and the switching circuit is controlled to be switched on or switched off according to the comparison result of the sampled voltage signal and a preset voltage signal, so that the constant temperature control of the electric iron is realized. The circuit of the constant temperature circuit is simple in structure, low in cost and high in temperature regulation response speed, and the difference between the actual working temperature and the nominal working temperature of the electric soldering iron is greatly reduced.
Example one
Referring to fig. 1, a functional block diagram of a constant temperature circuit in an embodiment is shown, the constant temperature circuit is used for controlling a constant temperature of an electric soldering iron, and the constant temperature circuit includes a first power circuit 1, a switch circuit 3, a heating circuit 2, a sampling circuit 4, a preset voltage circuit 6, and a comparison circuit 5. The first power supply circuit 1 includes a first AC electrical connection end for connecting with a live wire AC-L of an alternating current, and a first switch connection end connected with the switch circuit 3, and the first power supply circuit 1 is configured to convert the alternating current into a first direct current for the switch circuit 3. The switching circuit 3 includes a first connection terminal, a second connection terminal, and a third connection terminal. The first connection end of the switch circuit 3 is connected with the first switch connection end, the second connection end of the switch circuit 3 is connected with the comparison circuit 5, and the third connection end of the switch circuit 3 is connected with the heating circuit 2. When the switch circuit is turned on, the first power supply circuit 1 and the heat generating circuit 2 are connected to output the first direct current output from the first power supply circuit 1 to the heat generating circuit 2. When the switch circuit 3 is turned off, the connection of the first power supply circuit 1 and the heat generating circuit 2 is disconnected. The heating circuit 2 comprises a second alternating current connecting end, a second switch connecting end, a sampling circuit connecting end and a soldering iron heating core. The second alternating current connecting end is used for being connected with a zero line AC-N of alternating current, the second switch connecting end is connected with the switch circuit 3, and the sampling circuit connecting end is connected with the sampling circuit 4. The heating circuit 2 is used for converting the first direct current into heat energy through the iron heating core. The sampling circuit 4 comprises a first connecting end and a second connecting end, the first connecting end of the sampling circuit 4 is connected with the connecting end of the sampling circuit, and the second connecting end of the sampling circuit 4 is connected with the comparison circuit 5. The sampling circuit 4 is used for sampling the voltage of one connecting end of the heating core of the soldering iron so as to obtain a sampling voltage signal, and the sampling voltage signal is sent to the comparison circuit 5. The preset voltage circuit 6 includes a first connection end, the first connection end of the preset voltage circuit 6 is connected to the comparison circuit 5, and the preset voltage circuit 6 is configured to output a preset voltage signal to the comparison circuit 5. The comparison circuit 5 comprises a first connection end, a second connection end and a third connection end, the first connection end of the comparison circuit 5 is connected with the second connection end of the switch circuit 3, the second connection end of the comparison circuit 5 is connected with the second connection end of the sampling circuit 4, and the third connection end of the comparison circuit 5 is connected with the first connection end of the preset voltage circuit 6. The comparison circuit 5 is used for outputting a first switch signal when the value of the sampling voltage signal is not larger than the value of the preset voltage signal, and the switch circuit 3 is switched on in response to the first switch signal. The comparison circuit 5 is further configured to output a second switching signal when the value of the sampled voltage signal is greater than the value of the preset voltage signal, and the switching circuit 3 is turned off in response to the second switching signal.
In one embodiment, the constant temperature circuit further includes a second power circuit 7, and the second power circuit 7 includes a first connection terminal, a second connection terminal, and a third connection terminal. The first connection terminal of the second power circuit 7 is configured to be connected to a live line AC-L of the alternating current, and the second power circuit 7 is configured to convert the alternating current into a second direct current and output the second direct current through the second connection terminal and the third connection terminal of the second power circuit 7. The preset voltage circuit 6 further comprises a second connection terminal, and the second connection terminal of the second power supply circuit 7 is connected with the second connection terminal of the preset voltage circuit 6 for supplying power to the preset voltage circuit 6. The comparison circuit 5 further comprises a fourth connection terminal, and the third connection terminal of the second power supply circuit 7 is connected to the fourth connection terminal of the comparison circuit 5 for supplying power to the comparison circuit 5.
Referring to fig. 2, which is a schematic diagram illustrating a circuit connection of the constant temperature circuit in an embodiment, the first power circuit 1 further includes a diode D11, an anode of the diode D11 is connected to the first ac connection terminal, and a cathode of the diode D11 is connected to the first switch connection terminal. In one embodiment, one connection end of the soldering iron heating core Rn is connected to the second switch connection end, and the other connection end is connected to the second ac electrical connection end. The second alternating current connection end is grounded. The second switch connecting end is electrically connected with the sampling circuit connecting end.
In one embodiment, the switching circuit further includes a thyristor D31, a diode D32, and a resistor R31. The positive connecting end of the controlled silicon D31 is connected with the first connecting end of the switch circuit 3, the negative connecting end of the controlled silicon D31 is connected with the third connecting end of the switch circuit 3, and the control end of the controlled silicon D31 is connected with the negative electrode of the diode D32. One end of the resistor R31 is connected to the anode of the diode D32, and the other end is connected to the second connection terminal of the switch circuit 3. In one embodiment, the switch circuit 3 further includes a light emitting diode D33, and the light emitting diode D33 is connected in series between the diode D32 and the resistor R31.
IN one embodiment, the comparison circuit 5 further includes a comparator chip U1, the comparator chip U1 includes a pin-IN, a pin + IN, a pin V-, a pin V + and a pin OUT, the pin OUT of the comparator chip U1 is connected to the first connection terminal of the comparison circuit 5, the pin-IN of the comparator chip U1 is connected to the second connection terminal of the comparison circuit 5, and the pin + IN of the comparator chip U1 is connected to the third connection terminal of the comparison circuit 5. Pin V-of comparator chip U1 is connected to ground. Pin V + of comparator chip U1 is connected to the fourth connection of comparator circuit 5. IN one embodiment, the comparison circuit 5 further includes a resistor R51, and one end of the resistor R51 is connected to the pin OUT of the comparator chip U1, and the other end is connected to the pin + IN of the comparator chip U1. In one embodiment, the comparator chip U1 is model LM 321.
In one embodiment, the preset voltage circuit 6 further includes a resistor R61, a resistor R62, a resistor R63, a resistor R64, a resistor R65, a resistor R66, a resistor R67, and a resistor R68. One end of the resistor R61 is connected to the second connection end of the preset voltage circuit 6, and the other end is connected to the first connection end of the preset voltage circuit 6. One end of the resistor R62 is connected to the first connection terminal of the preset voltage circuit 6, and the other end is grounded. The resistor R63 and the resistor R64 are connected in series, one end of the series connection is connected with the first connection end of the preset voltage circuit 6, and the other end of the series connection is grounded. The resistor R65 and the resistor R66 are connected in series, one end of the series connection is connected with the first connection end of the preset voltage circuit 6, and the other end of the series connection is grounded. The resistor R67 and the resistor R68 are connected in series, one end of the series connection is connected with the first connection end of the preset voltage circuit 6, and the other end of the series connection is grounded.
As shown in fig. 1 and fig. 2, in an embodiment, the second power supply circuit 7 further includes a fourth connection terminal, and the second power supply circuit 7 is further configured to output the second direct current to the sampling circuit 4 through the fourth connection terminal of the second power supply circuit 7 to supply power to the sampling circuit 4. The sampling circuit 4 further includes a third connection terminal, a transistor Q41, a resistor R41, and a resistor R42. The third connection of the sampling circuit 4 is connected to the fourth connection of the second supply circuit 7. One end of the resistor R41 is connected to the third connection terminal of the sampling circuit 4, and the other end is connected to the control electrode of the transistor Q41. A first pole of the transistor Q41 is connected to the first connection terminal of the sampling circuit 4, and a second pole of the transistor Q41 is connected to the second connection terminal of the sampling circuit 4. One end of the resistor R41 is connected to the second connection terminal of the sampling circuit 4, and the other end is grounded. In one embodiment, transistor Q41 is of the type MMBT 13001.
Referring to fig. 3, a circuit connection diagram of the preset voltage circuit in another embodiment is shown, in which the preset voltage circuit 6 further includes a slide rheostat R71, a resistor R72, a slide rheostat R73, a resistor R74, and a resistor R75. The slide rheostat R71 and the slide rheostat R73 respectively comprise a first fixed end, a second fixed end and a first sliding end. The resistor R74 and the resistor R75 are connected in parallel, one end of the parallel connection is connected with the second fixed end of the slide rheostat R73, and the other end of the parallel connection is grounded. The first sliding end of the sliding rheostat R73 is connected with the first connection end of the preset voltage circuit 6, one end of the resistor R72 is connected with the first fixed end of the sliding rheostat R73, and the other end of the resistor R72 is connected with the second fixed end of the sliding rheostat R71. The first fixed end of the slide rheostat R71 is connected with the second connecting end of the preset voltage circuit 6, and the first sliding end of the slide rheostat R71 is connected with the first fixed end of the slide rheostat R71. When the preset voltage circuit shown in fig. 3 is adopted, if the constant temperature of the electric soldering iron needs to be changed, only the resistance value of the slide rheostat R73 needs to be changed, namely the voltage value of the preset voltage signal input to the voltage comparator U31 is changed. Because the slide rheostat R73 is an adjustable resistor, the heating temperature of the two-core adjustable constant-temperature electric soldering iron can be within a temperature output range, and each selected temperature value is stable.
Referring to fig. 4, a circuit connection diagram of the second power circuit in an embodiment is shown, in which the second power circuit further includes a diode D71, a resistor R70, a capacitor C70, and a diode D70. The anode of the diode D71 is connected to the first connection terminal of the second power supply circuit 7. One end of the resistor R70 is connected to the cathodes of the diode D71 and the diode D70, and the other end is connected to the second connection terminal, the third connection terminal, and the fourth connection terminal of the second power supply circuit 7. The anode of diode D70 is connected to ground. One end of the capacitor C70 is connected to the anode of the diode D70, and the other end is connected to the cathode of the diode D70.
Referring to fig. 5, a circuit connection diagram of the second power circuit in another embodiment is shown, in which the second power circuit further includes a toggle switch SW1, a diode D71, a resistor R70, a capacitor C70, and a diode D70. Toggle switch SW1 switch includes pins 1, 2, 3, 4 and 5. The anode of the diode D71 is connected to the first connection terminal of the second power supply circuit 7. One end of the resistor R70 is connected with the cathode of the diode D71, and the other end is connected with pin 1 of the toggle switch SW 1. Pin 1 of toggle switch SW1 is connected to the second, third and fourth connections of second power supply circuit 7. Pin 2 of toggle SW1 is connected to the cathode of diode D70. Pin 3, pin 4 and pin 5 of toggle switch SW1 are grounded. The anode of diode D70 is connected to ground. One end of the capacitor C70 is connected to the anode of the diode D70, and the other end is connected to the cathode of the diode D70. In one embodiment, toggle switch SW1 is model SK12F14G 5.
Referring to fig. 6, a schematic diagram of a working flow of a constant temperature circuit according to an embodiment is shown, where the working flow of the constant temperature circuit is as follows:
220V sine wave alternating current is input into the first power supply circuit through a live wire AC-L;
the diode D11 half-wave rectifies the ac power and outputs the ac power to the thyristor D31. The gate trigger voltage of the controlled silicon D31 is 0.8V, when the control voltage of the controlled silicon D31 is more than 0.8V, the controlled silicon D31 is conducted, the current flows through the controlled silicon D31 to start outputting the electric energy to the heating circuit, and when the control voltage is less than 0.8V, the controlled silicon D31 is cut off to stop outputting the electric energy to the heating circuit. The preset voltage circuit provides a reference voltage to pin + IN of the voltage comparator U1 of the comparison circuit. As an example of the preset voltage circuit shown in fig. 3, the formula of the reference voltage is:
V+=12V*R73/(R73+R72)=0.33V；
when the voltage value of the sampled voltage electrical signal input at the pin-IN of the voltage comparator U1 is less than 0.33V, the voltage comparator U1 outputs a high level from the pin OUT. At the moment, the light-emitting diode D33 emits light and can trigger the silicon controlled rectifier D31 to be conducted, so that the heating circuit obtains electric energy and starts to heat the heating core of the soldering iron.
When the voltage value of the sampled voltage electrical signal input at pin-IN of the voltage comparator U1 is equal to 0.33V. The voltage comparator U1 outputs a low level from the pin OUT. At this time, the light emitting diode D33 is extinguished, and at the same time, the thyristor D31 can be triggered to be cut off, so that the heating circuit loses electric energy, and the heating circuit stops heating.
Because the soldering iron heating core is a positive temperature coefficient resistor, the resistance value is larger when the temperature is higher, IN one embodiment, the resistance value of the soldering iron heating core is measured to be 220 ohms at normal temperature, the resistance value is about 700 ohms when the temperature reaches 400 ℃, different voltages can be generated under different resistance values, the conduction and the cut-off of the silicon controlled rectifier D31 can be controlled by sampling the real-time voltage of the soldering iron heating core and inputting the real-time voltage to a pin-IN of a voltage comparator U1, the voltage comparator U1 compares the sampled voltage signal with a preset voltage signal (reference voltage) output by a preset output voltage circuit and outputs a corresponding level signal, and finally the temperature of the soldering iron heating core of the heating circuit is controlled to realize the constant temperature control of a soldering iron head. The triode Q41 of the sampling circuit can isolate the heating core of the electric soldering iron due to the high impedance characteristic of the PN junction of the CB pole, so that the high-voltage protection of the voltage-voltage comparator U1 is realized, and the breakdown damage is avoided.
The embodiment of the application also discloses an electric soldering iron which comprises the constant temperature circuit, a power line, a handle barrel, a temperature control circuit PCB, a two-core soldering iron heating core, a steel pipe, a soldering iron head and the like. Referring to fig. 7, a schematic diagram of the connection between the circuit board of the soldering iron in one embodiment is shown, the constant temperature circuit is disposed on the temperature control circuit PCB10, and the temperature control circuit PCB10 is disposed in the handle barrel. After the constant temperature circuit is connected with 220V alternating current, the heating core Rn of the soldering iron can be normally heated, meanwhile, the soldering iron head is heated, and the soldering iron can be heated and melted with tin within 30 seconds of working, so that soldering work is carried out. In one embodiment, the rated output power of the electric soldering iron is 40W. In one embodiment, the heating temperature of the electric soldering iron is 400 ℃, and the electric soldering iron can generate different constant temperatures by adjusting the slide rheostat R73.
The electric iron that this application embodiment disclosed, under the condition that does not use four-core flatiron to generate heat the core, utilize the flatiron to generate heat the resistance characteristic of core under the different temperatures, sample the different voltages that produce from this, and feed back to the voltage comparator, export different control signal of telecommunication after the voltage comparator comparison, control LED lamp and silicon controlled rectifier switch on and end, the final control flatiron generates heat the time that generates heat of core, in order to guarantee that the flatiron generates heat the temperature stability of core. In addition, in one embodiment, the constant temperature circuit uses a transistor Q41(MMBT13001) to isolate high voltage by using the PN junction characteristic of the transistor, so that the voltage comparator (LM321) is protected from being damaged. The constant temperature control of the electric soldering iron with the two-core heating iron core is realized on the basis of not obviously increasing too much cost, the cost is lower than that of a four-core heating iron core, the temperature is constant compared with that of a common two-core heating iron core, and the difference between the actual working temperature and the nominal working temperature of the electric soldering iron is reduced.
In the embodiment of the application, a constant temperature circuit is disclosed, and the constant temperature circuit comprises a first power supply circuit, a switch circuit, a heating circuit, a sampling circuit, a preset voltage circuit and a comparison circuit. Wherein, first power supply circuit is used for converting an alternating current into first direct current, and switch circuit connects first power supply circuit and heating circuit when being used for switching on, and heating circuit is used for the electric energy conversion heat energy with first direct current, and sampling circuit is used for the voltage sampling to the flatiron core that generates heat, and preset voltage circuit is used for exporting preset voltage signal, and comparison circuit is used for comparing sampling voltage signal and preset voltage signal to according to the result control switch circuit switch on or break off of comparison. This application generates heat the principle that the resistance value that the core corresponds along with the temperature variation also changes according to the flatiron, generates heat the voltage of core to the flatiron and samples to according to the comparative result control switch circuit of sampling voltage signal and presetting voltage signal switch on or break off, and then realize the thermostatic control of electric iron. The circuit of the constant temperature circuit is simple in structure, low in cost and high in temperature regulation response speed, and the difference between the actual working temperature and the nominal working temperature of the electric soldering iron is greatly reduced.
The present application has been described with reference to specific examples, which are provided only to aid understanding of the present application and are not intended to limit the present application. For a person skilled in the art to which the application pertains, several simple deductions, modifications or substitutions may be made according to the idea of the application.
Claims (10)
1. A constant temperature circuit for an electric soldering iron is characterized by comprising a first power supply circuit, a switch circuit, a heating circuit, a sampling circuit, a preset voltage circuit and a comparison circuit;
the first power supply circuit comprises a first alternating current connection end and a first switch connection end; the first alternating current connecting end is used for being connected with a live wire of alternating current, and the first switch connecting end is connected with the switch circuit; the first power supply circuit is used for converting the alternating current into a first direct current to the switch circuit;
the switch circuit comprises a first connecting end, a second connecting end and a third connecting end; the first connecting end of the switch circuit is connected with the first switch connecting end, the second connecting end of the switch circuit is connected with the comparison circuit, and the third connecting end of the switch circuit is connected with the heating circuit; when the switch circuit is conducted, connecting the first power supply circuit and the heating circuit to output the first direct current output by the first power supply circuit to the heating circuit; when the switch circuit is disconnected, disconnecting the first power supply circuit and the heating circuit;
the heating circuit comprises a second alternating current connecting end, a second switch connecting end, a sampling circuit connecting end and a soldering iron heating core; the second alternating current connecting end is used for being connected with a zero line of alternating current, the second switch connecting end is connected with the switch circuit, and the sampling circuit connecting end is connected with the sampling circuit; the heating circuit is used for converting the first direct current into heat energy through the soldering iron heating core;
the sampling circuit comprises a first connecting end and a second connecting end, the first connecting end of the sampling circuit is connected with the connecting end of the sampling circuit, and the second connecting end of the sampling circuit is connected with the comparison circuit; the sampling circuit is used for sampling the voltage of one connecting end of the heating core of the soldering iron so as to obtain a sampling voltage signal and sending the sampling voltage signal to the comparison circuit;
the preset voltage circuit comprises a first connecting end, and the first connecting end of the preset voltage circuit is connected with the comparison circuit; the preset voltage circuit is used for outputting a preset voltage signal to the comparison circuit;
the comparison circuit comprises a first connection end, a second connection end and a third connection end, the first connection end of the comparison circuit is connected with the second connection end of the switch circuit, the second connection end of the comparison circuit is connected with the second connection end of the sampling circuit, and the third connection end of the comparison circuit is connected with the first connection end of the preset voltage circuit; the comparison circuit is used for outputting a first switching signal when the value of the sampling voltage signal is not greater than the value of the preset voltage signal, and the switching circuit responds to the first switching signal to be conducted; the comparison circuit is further used for outputting a second switching signal when the value of the sampling voltage signal is larger than the value of the preset voltage signal, and the switching circuit is switched off in response to the second switching signal.
2. The thermostat circuit of claim 1, further comprising a second power circuit comprising a first connection, a second connection, and a third connection; the first connecting end of the second power supply circuit is used for being connected with the live wire of the alternating current, the second power supply circuit is used for converting the alternating current into a second direct current, and the second direct current is output through the second connecting end and the third connecting end of the second power supply circuit; the preset voltage circuit further comprises a second connecting end, and the second connecting end of the second power supply circuit is connected with the second connecting end of the preset voltage circuit so as to be used for supplying power to the preset voltage circuit; the comparison circuit further comprises a fourth connection end, and the third connection end of the second power supply circuit is connected with the fourth connection end of the comparison circuit so as to provide power for the comparison circuit.
3. The thermostat circuit of claim 2, wherein the first power supply circuit further includes a diode D11, an anode of a diode D11 being connected to the first ac electrical connection terminal, a cathode of a diode D11 being connected to the first switch connection terminal;
and/or one connecting end of the soldering iron heating core is connected with the second switch connecting end, and the other connecting end of the soldering iron heating core is connected with the second alternating current connecting end; the second alternating current connection end is grounded; the second switch connecting end is electrically connected with the sampling circuit connecting end.
4. The thermostat circuit of claim 2, wherein the switching circuit further comprises a thyristor D31, a diode D32, and a resistor R31;
the positive connecting end of the controlled silicon D31 is connected with the first connecting end of the switch circuit, the negative connecting end of the controlled silicon D31 is connected with the third connecting end of the switch circuit, and the control end of the controlled silicon D31 is connected with the negative electrode of the diode D32;
one end of the resistor R31 is connected with the anode of the diode D32, and the other end is connected with the second connection end of the switch circuit.
5. The thermostat circuit of claim 4, wherein the switch circuit further comprises a light emitting diode D33, and a light emitting diode D33 is connected in series between the diode D32 and the resistor R31.
6. The thermostat circuit of claim 1, wherein the comparator circuit further comprises a comparator chip U1, the comparator chip U1 comprises a pin-IN, a pin + IN, a pin V-, a pin V + and a pin OUT, the pin OUT of the comparator chip U1 is connected to the first connection terminal of the comparator circuit, the pin-IN of the comparator chip U1 is connected to the second connection terminal of the comparator circuit, and the pin + IN of the comparator chip U1 is connected to the third connection terminal of the comparator circuit; pin V-of comparator chip U1 is grounded; pin V + of comparator chip U1 is connected to the fourth connection of the comparator circuit.
7. The thermostat circuit of claim 2, wherein the preset voltage circuit further comprises a resistor R61, a resistor R62, a resistor R63, a resistor R64, a resistor R65, a resistor R66, a resistor R67, and a resistor R68;
one end of the resistor R61 is connected with the second connecting end of the preset voltage circuit, and the other end of the resistor R61 is connected with the first connecting end of the preset voltage circuit;
one end of the resistor R62 is connected with the first connection end of the preset voltage circuit, and the other end of the resistor R62 is grounded;
the resistor R63 and the resistor R64 are connected in series, one end of the resistor R63 and the resistor R64 after being connected in series is connected with the first connecting end of the preset voltage circuit, and the other end of the resistor R64 after being connected in series is grounded;
the resistor R65 and the resistor R66 are connected in series, one end of the resistor R65 and the resistor R66 after being connected in series is connected with the first connecting end of the preset voltage circuit, and the other end of the resistor R66 after being connected in series is grounded;
the resistor R67 and the resistor R68 are connected in series, one end of the series connection is connected with the first connection end of the preset voltage circuit, and the other end of the series connection is grounded.
8. The thermostat circuit of claim 2, wherein the preset voltage circuit further comprises a slide varistor R71, a resistor R72, a slide varistor R73, a resistor R74, and a resistor R75; the sliding rheostat R71 and the sliding rheostat R73 respectively comprise a first fixed end, a second fixed end and a first sliding end;
the resistor R74 and the resistor R75 are connected in parallel, one end of the parallel connection is connected with the second fixed end of the slide rheostat R73, and the other end of the parallel connection is grounded;
the first sliding end of the sliding rheostat R73 is connected with the first connection end of the preset voltage circuit,
one end of the resistor R72 is connected with the first fixed end of the slide rheostat R73, and the other end is connected with the second fixed end of the slide rheostat R71;
the first fixed end of the slide rheostat R71 is connected with the second connecting end of the preset voltage circuit, and the first sliding end of the slide rheostat R71 is connected with the first fixed end of the slide rheostat R71.
9. The thermostat circuit of claim 2, wherein the second power supply circuit further comprises a fourth connection, the second power supply circuit further for outputting the second direct current to the sampling circuit through the fourth connection of the second power supply circuit to provide power to the sampling circuit;
the sampling circuit further comprises a third connecting end, a triode Q41, a resistor R41 and a resistor R42; the third connecting end of the sampling circuit is connected with the fourth connecting end of the second power supply circuit;
one end of the resistor R41 is connected with the third connecting end of the sampling circuit, and the other end of the resistor R41 is connected with the control electrode of the triode Q41;
a first pole of the triode Q41 is connected with the first connecting end of the sampling circuit, and a second pole of the triode Q41 is connected with the second connecting end of the sampling circuit;
one end of the resistor R41 is connected with the second connecting end of the sampling circuit, and the other end is grounded.
10. An electric soldering iron, comprising a thermostatic circuit as claimed in any one of claims 1 to 9.
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| CN202111367511.3A CN113894379B (en) | 2021-11-18 | 2021-11-18 | Constant temperature circuit for electric soldering iron and electric soldering iron |
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| CN202111367511.3A CN113894379B (en) | 2021-11-18 | 2021-11-18 | Constant temperature circuit for electric soldering iron and electric soldering iron |
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| CN113894379B CN113894379B (en) | 2023-07-04 |
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