Need help designing a simple flip flop for 12V trigger

[RickRay]

See the attached circuit circled in red. The circuit senses a signal and provides -12V for on and +12V for off, just the opposite of ICEPower modules. I am wanting to have the circuit provide +12V for on and 0V for off. A little more complicated than a simple flip flop. Any ideas? I can build a simple circuit on a breadboard and piggyback off the +-15V to power it.

 

[rayma]

This should work. Just connect it after the given circuit.
You might need a buffer depending on loading.

-12V in gives +12V out

+12V in gives 0V out

 

[RickRay]

Thank you so much. I hadn't thought about just using a transistor, that makes sense. I was locked into a simple opamp. Pretty sure the load is insignificant. Class D amp I'm wanting to use shows a 47k resistor in series with the internal circuitry.

 

[rayma]

Sounds like it will be ok. Don't leave the diode out.

 

[RickRay]

Also, substituting a 2N5551 for the 2N2222A, didn't have any. Breadboarding it first.

 

[RickRay]

Not working with the 2N5551. Switches between 9V and 10V. I'll get some 2N2222A in my next Mouser order.

 

[xa488]

Rayma's solution should work with any transistor. Are you sure the transistor is connected correctly?

 

[rayma]

Yeah, test the transistor with your DVM diode function before installing it.
Double check the lead pinout, E - B - C (left to right).

 

[RickRay]

Holy sheep dip. I always check the leads with a transistor checker. The elcheapo got it right. Guess I'm back to using it. The FNIRSI tester gives the wrong pinout. See the picture below.

 

[RickRay]

Going to eat will check it the correct way a little later. I'm sure it will work.

 

[RickRay]

Working perfect, 95mV when off, 14.99V when on.

 

[rayma]

Loading will reduce the positive output level. Depending on the amplifier circuitry, that may not matter.

 

[RickRay]

I'll see what it looks like with 47k in series with ground.

 

[steveu]

Flip D111 and swap +/-15 for on/auto.

 

[RickRay]

Got it figured out. I just adjust the 1k resistor to get the needed voltage on the input of the amp, of course, depending on the internal resistance on the input of the amp. Got it to 12.2V with the 47k in series to ground. I'll start with that and adjust as needed.

 

[RickRay]

Flip D111 and swap +/-15 for on/auto.

Wish I could, but the opamps are quads.

 

[RickRay]

What this is, is a feature board on a subwoofer. The SMPS power supply smoked and it is way to smoked to fix. So I am putting an ICEpower 300AS1 module in it, ran off the feature board. It will look stock from the outside.

​

 

[steveu]

Wish I could, but the opamps are quads.

Don't touch the op-amps. Just the diode and the switch wiring.

 

[RickRay]

Got it, makes sense, but easier said than done without hacking it up. The switch is mechanically tied to the board. The circuit above is working perfect, I'll go with it.

 

[rayma]

Good decision. Now the board documentation is not voided.
But add some info to the file with the original schematic for the adapter circuit.