Auto PowerOFF Power Supply!

[Shahriar]

Hi

I have build two laboratory equipment for two English Language Institue.
Few days ago, When I went to one of these laboratory, I noticed that
the teacher has forgotten to turn the centeral SET off so The VCR connected
to the set has reached to the end of the Film, so the TV had Turned off automatically.
but my set has been working for 3 Days.
So I decided to build an AutoPower off Power supply. I know how to turn off the power supply
But my problem is how to detect that there is no Audio Or Video signal at the
SCA inputs of the set. The Power supply is to be turned off by a Microcontroller.

ThanX in advance.
Shahriar

View attachment 36527

 

[MP1]

It would be simpler to find a smarter teacher ;D
However, if this is not possible, you could write a clock program and use a micro port pin to trigger a relay on or off. You can also find timers in electronics stores which will allow you to set the on and off switch to different times of the day. This would be a quickl solution which is already made.

MP

 

[Shahriar]

Dear MP

As I said, I know how to power off the power supply
and I know how to use timers.
THE PROBLEM IS THAT how I detect that there is no AUDIO or VIDEO signal at the Input.
I have think about it and I want to use the following circuit. Although it is not the FINISHED circuit
Please tell me the problems you see with the circuit
ThanX in advance.
Shahriar

View attachment 36532