Power/Output relay control circuit

[alexcd]

I thought it would be nice to create a relatively simple power/speaker output relay circuit for amp builders such as myself. Here were my requirements.

* accept momentary push button to toggle power state
* accept 12V trigger (actually 5-24V range) from receiver but with ability to change power state with on-device button.
* must have two outputs, power breaker and speaker outputs (helps with those nasty sounds at shut down)
* uses a wide range of voltages and very little power since it will most likely run whenever plugged in
* on board AC-DC (35V max to 5VDC)..
* accepts external relay power (any voltage will do) up to ~10A so you can use monster relays
* small outline but all through-hole parts (ended up 2"x4" with mounting holes)

So here is the sequence of events when you give the circuit juice.

1) There is a 0.5 second delay where nothing with happen (clears the logic states and makes sure nothing bad happens) when you initially power the unit. This is a safely precaution and should not be a problem for anyone really.

2) Toggle power with power button OR 12V trigger

3) Power turns on instantly. Speaker outputs are delayed 1 second.

4) Toggle power with power button OR 12V trigger

5) Power and speaker outputs are turned off instantly.

The circuit has been thoroughly simulated in PSPICE.

The parts cost $9.30+SH (all Mouser) and I'm hoping to get at least 20 requests for boards to drop that price to $6 each. I would expect the total to be around $20 per board.