555 DC power supply circuit diagram of a protection device

Posted on Mar 28, 2007

Circuit diagram for the DC power supply protection circuit. The device consists of buck rectifier power supply, monostable delay circuit, relay control circuit, audio feedback

555 DC power supply circuit diagram of a protection device
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oscillation circuit. The entire circuit DC voltage Vdd, and Vdd where the buck rectifier power supply is + (5 ~ 12) V, depending on the value of specific VDD regulator block IC1 may be. Monostable delay circuit consists of IC2 (555) and R3, C4 and other components. Usually, normally closed contact J1-1 is closed, so that the potential of pin IC2 normal load is high (1V above), when the load is short-circuited due to 555 feet potential is low ( 0.6V) and is forced to reset output pin low J pull the relay contacts J1-1 off, cut off the short-circuit load. Meanwhile contacts J2-2, J3-3 respectively connected, so that the audio feedback oscillator BG1, BG2, C6, C7, R6 and composition by applying a voltage oscillation, which issued about lkHz acoustic signal to alert the use to pay attention. After contact J3-3 switched, C4 is charged through R3 so IC potential drop foot, when the potential of pin falls below 1/3VDD, 555 occurs is set. high output enable pin J release, contact J1-1 connected. If this time is still short-circuited, then protected. C4 of the respective charging time is 555 delay guard time td 1.1R3C4. Protection time can be adjusted by changing the time constant R3C4. The protection circuit may short-circuit protection DC voltage source, which can be used as an annex to the voltage source, or any power supply design, integrated design. Its l.5 ~ 50V DC output voltage in the range of source in the event of a short circuit at a speed of 0.1 seconds to switch the load, for protection, and this delay circuit also has auto-recovery function.

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