This circuit prevents surges. From the opening is switched off or power failure. The damage to electrical appliances. The circuit will switch to use a short period before Power raising circuit to go.
When raising the power supply 9-volt circuit then. Circuit delay. The duration of charging C1. VR1 is adjusted with time.When C1 is fully charged, it will be pressure to bias the pin G of the FET 2N4891 . Q1 to conduct work to trigger to pin G of the SCR to run. When SCR relay will work to cut the flow circuit to work. If you want to delay it longer add the C1.
If you think that This circuit is not good enough. For your work. It is hard to find equipment. You do not have it now. These circuits may be viewed below. It may be appropriate for you.
1. Power on delay circuit
2. Surge protector
3. OFF After Delay Switch by Mosfet
4. Automatic timer switch with ua741
5. Simple Delay turn on the monitor
6. Small surge protector using delay system by C1815
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