Automatically disconnect power supply circuit
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Using this circuit diagram can be made a simple circuit that automatically disconnects , the power supply voltage of an electronic device.
Coupling is based on the energy contained in impulse control connection. At the push of S1, power supply voltage becomes immediately available at the terminals of C2. Due to the difference of R2-C2 voltage is briefly connected to IC1's input V + by D1. This energy is sufficient for IC1 to trigger activation of timing, and therefore T1 will be placed in conduction. This transistor provides energy to integrated circuit for the rest of the cycle. At the end of the cycle, T1 is blocked and not deliver energy. Connection state is given by: t = (P1 + R4) C3 [seconds].
Maximum switched current T2 should not exceed 350 mA and voltage can be between 5 V and 15 V (minimum triggering level is 5 V).
Period until release, with values given in the diagram, is 1 to 100 seconds.