JPS5824319Y2 - tape recorder - Google Patents

Description

[Detailed description of the invention] This invention relates to a tape recorder for the purpose of power saving, and it is possible to monitor the recording by applying normal voltage to the power amplifier circuit only when monitoring the recording using earphones etc. from the monitor jack during recording. When not being monitored, the power supply to the power amplifier circuit is cut off to reduce current consumption.

Conventionally, for example, in a tape recorder that has a recording circuit and a playback circuit independently, a playback power amplifier circuit is used to amplify the microphone input during recording and perform recording monitoring. Electricity is wasted because current flows through the amplifier circuit.

This is extremely uneconomical considering that more than 90% of the current consumption of the entire amplifier is consumed mainly by the power amplifier circuit.

Furthermore, to help understand this, an example of a conventional circuit is shown in FIG.

In the figure, 1 is a power supply, 2 to 9 are resistors, 10 to 13 are transistors, 14 to 18 are capacitors, 19 is an input transformer,
20 is the output Lance, 21 is the monitor jack, 22
is a speaker, 23 is a recording/playback head, 24 is a recording amplifier, 25 is a microphone, 26 is a variable resistor, 27 is a playback amplifier, 28.29 is a recording/playback selector switch, 30
is a diode.

FIG. 1 shows the recording state. The input from the microphone 25 is amplified by the recording amplifier 24, supplies a recording signal to the head 23, and is also guided to the power amplifier circuit through the capacitor 16, so that the earphone flag is connected to the monitor jack 21. By inserting the , you can monitor the recording.

Even if the earphone plug is removed from the monitor jack 21 at this time, a signal is supplied to the resistor 9 and the reproduction power amplifier circuit operates according to the signal, consuming current, which is extremely uneconomical and It was a waste of battery power.

The present invention aims to eliminate such drawbacks and to provide a tape recorder which is useful for IC implementation, since the recording/playback changeover switch can be integrated into one circuit.

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 2, the same components as those in the circuit of FIG. 1 are designated by the same reference numerals, and their explanations will be omitted.

31.32.33 are resistors, 34°35 are capacitors, 3
6.37 is a transistor.

Figure 2 shows the recording status and monitor jack 2.
When the earphone plug is not inserted into 1, power supply 1 is connected to resistor 3.
1. It is supplied to the secondary side of the output transformer 20 through the movable contact piece and the fixed contact piece of the monitor jack 21.

Since the secondary DC resistance of the output transformer 200 is sufficiently smaller than the resistor 33, almost no voltage is applied to the base of the transistor 36, and the transistor 36 is in a cut-off state.

A base bias is applied to the transistor 37 from the recording side contact R of the recording/playback switch 28 through the resistor 32, which turns it on and pulls down the base of the transistor 10 to ground potential 1, setting the transistor 10 in the cut-off state and turning the power amplifier off. The power consumption of the power amplifier circuit is eliminated by cutting off the voltage supplied to the circuit.

Next, when the earphone plug is inserted into the monitor jack 21, the movable contact piece of the monitor jack 21 separates from the fixed contact piece, so it is connected to the transistor 3 through the resistor 3133.
A bias is applied to the base of transistor 6 from power supply 1, turning on transistor 36, which cuts off transistor 37, causing transistor 10 to function as a normal ripple filter, and supplying voltage to the power amplifier circuit. It becomes operational and normal recording monitoring can be performed.

Note that during reproduction, since no voltage is supplied to the transistor 36 through the resistor 32, the transistor 37 is cut off and the power amplifier circuit operates normally regardless of whether or not the voltage is supplied to the base of the transistor 36.

As is clear from the above embodiments, the present invention supplies the recording signal from the microphone to the head and also to the power amplifier circuit, and by inserting the plug into the monitor jack connected to the power amplifier circuit, the earphone can be heard. In a tape recorder that is capable of recording monitoring, etc., the power supply to the power amplifier circuit is cut off when a plug is not inserted into the monitor jack, and according to this, recording monitoring is not possible. In other words, when there is no plug inserted into the monitor jack, the power supply to the power amplifier circuit is cut off, which prevents the power amplifier circuit from consuming power for unnecessary operations. Especially in tape recorders that use batteries as a power source, an idle link current of several tens of mA flows through the power amplifier circuit even when there is no output, so it is very effective in preventing waste of this idle link current and reducing battery consumption. It is.

[Brief explanation of the drawing]

FIG. 1 is a recording/playback circuit diagram of a conventional tape recorder, and FIG. 2 is a recording/playback circuit diagram of an embodiment of the present invention. 1...Power supply, 2-8, 31, 32, 33...Resistance,
10-13, 36, 37...transistor, 14-1
8.34.35... Capacitor, 19... Input transformer, 20... Output transformer, 21... Monitor jack, 22... Speaker, 23... Recording/playback head, 24... Dividing amplifier, 28... Recording/playback selector switch, 30... Diode.

Claims (1)

[Scope of utility model registration request] A tape recorder that supplies a recording signal from a microphone to a head and a power-up circuit, and allows recording to be monitored using earphones or the like by inserting a plug into a monitor jack connected to the power-up circuit, A contact piece that is switched when a plug is inserted into the monitor jack supplies power to a first transistor that is turned on when the plug is not inserted, and is turned off when the first transistor is turned on. A second transistor is provided for controlling the voltage supplied to the power amplifier circuit, and when a plug is not inserted into the monitor jack, the power supply to the power amplifier circuit is cut off by turning off the second transistor. A tape recorder configured as follows.