Will this circuit work?

[Tdale]

I asked about using optocouplers for channel switching, on a norwegian forum. I didn't explain exactely how the OD/Clean switch in the Dumble usually is wired, so I think they thought I meant just a simple A/B switch.

But they claim that it will work for the OD type switching too. I have two problems understanding it.

First of all, I can't really see that it would work at all. It is supposed to work like this: When transistor A openes the signal path to ground, the Input signal will go to B, and when transistor B is opened to ground, the signal will flow to A.

To me it seems that the input signal would go to ground, and not much would be left for the output at all. It sounds like they mean that the signal will be divided between the two 68K resistors, and stay divided no matter what happenes to the transistors.

Also, if it worked, I can't see how this could be used in a Dumble, since the OD section needs to be grounded when it's in Clean mode.

Does the circuit make any sense to you at all?

Tommy

[BobW]

Tommy,
The A circuit works like this:
1. If A is at 0 VDC, then the A transistor is OFF and the Input signal is present at the A output.
2. If A is at 1 VDC or greater, then the A transistor is ON and any signal that was present at the A output is now shunted to ground via the 100 Ohm Collector resistor.

The B circuit works exactly the same as the A circuit. However, the problem I see with this circuit is that when either transistor is turned ON, there will be a slight signal loss since the Input signal now sees a 68.1K, 68.1K resistance to ground. hth