CN204740076U

CN204740076U - Make things convenient for circuit of perception temperature

Info

Publication number: CN204740076U
Application number: CN201520395573.9U
Authority: CN
Inventors: 林碧琴
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-06-07
Filing date: 2015-06-07
Publication date: 2015-11-04
Anticipated expiration: 2025-06-07

Abstract

The utility model provides a make things convenient for circuit of perception temperature, including 555 time base chip and thermistor, thermistor's resistance risees and the grow along with the temperature, thermistor's one end is connected with the one end of first resistance and 555 time base chip's discharge end, thermistor's the other end and 555 time base chip's reset terminal, 555 time base chip's power anode, the one end and the power supply of second resistance connect, the other end of first resistance and the one end of electric capacity, 555 time base chip's low trigger end and 555 time base chip's high trigger end are connected, the other end of electric capacity, 555 time base chip's power negative terminal, red emitting diode's minus earth, the anodal of red emitting diode is connected with 555 time base chip's the output and the other end of second resistance. The utility model has the advantages of simple structure need not program code, the easy realization.

Description

A kind of circuit facilitating sense temperature

Technical field

The utility model relates to electronic circuit field, particularly relates to a kind of circuit facilitating sense temperature.

Background technology

What existing temperature sensing circuit generally adopted is the mode that MCU adds numeral method temperature, has cost high, and development difficulty is large, the shortcomings such as easy fault.

Summary of the invention

The technical problems to be solved in the utility model, is to provide a kind of circuit facilitating sense temperature, solves temperature sensing circuit cost high, and development difficulty is large, the problem of easy fault.

The utility model is achieved in that a kind of circuit facilitating sense temperature, base chip and thermistor when comprising 555, the resistance of described thermistor raises with temperature and becomes large, when one end of thermistor and one end of the first resistance and 555, the discharge end of base chip is connected, the other end of thermistor and 555 time base chip reset terminal, the power positive end of base chip when 555, one end of second resistance is connected with power supply, the other end of the first resistance and one end of electric capacity, when 555 base chip low triggering end with 555 time base chip high-triggering end be connected, the other end of electric capacity, the power supply negative terminal of base chip when 555, the minus earth of red light emitting diodes, the positive pole of red light emitting diodes with 555 time the output terminal of base chip and the other end of the second resistance be connected.

The utility model tool has the following advantages: structure is simple, without the need to program code, easily realizes.

Accompanying drawing explanation

Fig. 1 is circuit diagram of the present utility model.

Embodiment

By describing technology contents of the present utility model, structural attitude in detail, realized object and effect, accompanying drawing is coordinated to be explained in detail below in conjunction with embodiment.

Refer to Fig. 1, the utility model provides a kind of circuit facilitating sense temperature, base chip NE555 and thermistor RD1 when comprising 555, the resistance of described thermistor raises with temperature and becomes large, when one end of thermistor and one end of the first resistance R1 and 555, the discharge end of base chip is connected, the other end of thermistor and 555 time base chip reset terminal, the power positive end of base chip when 555, one end of second resistance R2 is connected with power supply, the other end of the first resistance and one end of electric capacity, when 555 base chip low triggering end with 555 time base chip high-triggering end be connected, the other end of electric capacity, the power supply negative terminal of base chip when 555, the minus earth of red light emitting diodes D1, the positive pole of red light emitting diodes with 555 time the output terminal of base chip and the other end of the second resistance be connected.

Principle of work of the present utility model is as follows: electric capacity C1 can be charged by RD1, R1, and is discharged by R1, and dutycycle is controlled by RD1 and R1, and the discharge and recharge of electric capacity C1 repeats between VCC/3 and 2VCC/3, and VCC is power supply voltage, process analysis procedure analysis:

1. initial capacitance voltage is a little less than VCC/3, now exports high level, and discharge end is closed, and VCC is to capacitor charging time constant 0.693 (RD1+R1) C; C is the value of electric capacity C1.

2. be charged to a little more than VCC/3, high level before exporting maintenance with reference to truth table, discharge end is closed, and VCC is to C charging rate 1/ (RD1+R1) C.

3. be charged to a little more than 2VCC/3, output low level, discharge switch is opened, capacitor discharge time constant 1/R1*C.

4. discharge into a little less than 2VCC/3, enter maintenance state, capacitor discharge time constant 0.693R1*C;

5. discharge into and enter 1 a little less than VCC/3, and start circulation.

Particularly, high level time: the time of VCC/3 to the 2VCC/3 that charges through RD1, R1; Low level time: the time discharging into VCC/3 through R1 from 2VCC/3; Cycle is 0.693 (RD1+2R1) C, dutycycle 1-R1/ (RD1+2R1).Namely along with the rising of temperature, the resistance of thermistor constantly rises, and brings dutycycle constantly to rise, thus the brightness of red light emitting diodes is brighter.User sees that namely brighter red light emitting diodes can know that Current Temperatures rises, as see burn red iron just can know iron very boiling hot, avoid by numerical monitor modes such as charactrons.Structure is simple, cost is low, also facilitates illiterate people to understand the height of temperature simultaneously.

The foregoing is only embodiment of the present utility model; not thereby scope of patent protection of the present utility model is limited; every utilize the utility model instructions and accompanying drawing content to do equivalent structure or equivalent flow process conversion; or be directly or indirectly used in other relevant technical fields, be all in like manner included in scope of patent protection of the present utility model.

Claims

1. one kind facilitates the circuit of sense temperature, it is characterized in that: base chip and thermistor when comprising 555, the resistance of described thermistor raises with temperature and becomes large, when one end of thermistor and one end of the first resistance and 555, the discharge end of base chip is connected, the other end of thermistor and 555 time base chip reset terminal, the power positive end of base chip when 555, one end of second resistance is connected with power supply, the other end of the first resistance and one end of electric capacity, when 555 base chip low triggering end with 555 time base chip high-triggering end be connected, the other end of electric capacity, the power supply negative terminal of base chip when 555, the minus earth of red light emitting diodes, the positive pole of red light emitting diodes with 555 time the output terminal of base chip and the other end of the second resistance be connected.