Recorders automatic shutdown circuit diagram TWH8778

Posted on Mar 28, 2007

As shown in FIG Xin US recorders automatically circuitry. The circuit mainly uses a new power switching device TWH8778, making simple, without debugging. TWH8778 shape and each

Recorders automatic shutdown circuit diagram TWH8778
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function of the foot as shown in Figure below, the control terminal feet, when the pin voltage is greater sub-threshold voltage (approximately 1.6V), the electronic switch is closed, O, feet on. When the touch switch touch BG1 and power between the contact sheet, BG1 conduction, so that the voltage drop on R1 TWH8778 closure, tape recorders because the power is turned on and working properly. If the recorders are playing in the audio signal C3 BG3 coupled to the base, so that BG2 conduction, BG2 there is base current in the conduction state, the voltage drop on R1 also allows the switch to lock TWH8778. When no audio signal, BG1 and BG2 are closing, TWH8778 because feet lose voltage switch off, tape recorders and automatic shutdown.In addition, the large capacitor 1000 F BG3 collector corresponding long discharge time constant, and therefore in the absence of an audio signal can also provide the current for a certain time BG2, BG2 to make a gap in the signal will not be cut, TWH8778 switch will not immediately disconnect, thereby effectively preventing the situation due to erroneous signal the emergence of a gap shutdown.

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