BJT Switch / Transistor-switch - how to?

[jakenold]

Dear fellow tinkerers.

I wish to create at circuit, that works kinda like the FET bypass in most BOSS and Ibanez pedals. I need it to pass ~ 5V when it's on and 0V when it's off and I need it to be activated by a momentary SPST-switch found in most BOSS and Ibanez pedals.

I've tried searching both here and on Google with no luck, and I can't seem to get my reverseengineered model to work.

Thanks in advance for any input!

[R.G.]

It's not clear from your description exactly what you're doing.

The Boss switching has two parts - a toggle flipflop triggered by a momentary switch, and then the JFETs that are controlled by it and pass signal in series when turned on.

This 5V and 0V you're trying to pass - are you trying to power some other circuit with it? Or turn on an LED? Is it a signal, which is to say, no significant current, or is it power, 1ma to many ma? Or is it passing 5V to ground?

All these things matter. What are you trying to do?

[jakenold]

Dear R.G. - thanks for your reply!

I am sorry, it's 4:49AM here in Denmark, and I've been tinkering with this all night.

What I want to do is to activate a relay. The current circuit of the BOSS and Ibanez pedals only give about 2,5V for the LED (which I thought I'd steal for the relay), which isn't enough for my 5V relays - and I couldn't find a sufficient 3V equivalent. So what I wanna do, is make a flip-flop circuit like that, to which I attach the stock switch of the BOSS or Ibanez, and get true bypass like that, without drilling and replacing the switch. (On the drawingboard, that sounded like a very good idea  )

[R.G.]

Wow, that's dedication!

OK, in that situation, use another NPN transistor. Connect its base through a resistor to the side of the Boss flipflop that goes high when you want the relay to be on. Connect its emitter to ground. Connect its collector to the (-) side of the relay coil, and connect the (+) side of the relay coil to +5V. Connect a diode anode to the relay coil (-) and cathode to the relay coil (+).

Now when the Boss flipflop goes high, even if it's only 2.5V, there is enough voltage to turn on the transistor. The transistor pulls the relay coil down.

Size the resistor to the base to not eat too much current. Try 10K to start, then go lower if that doesn't work.

Yell back at us if it doesn't work.

[Torchy]

.

[jakenold]

Okay, I'm bringing this up again as I simply cannot get it to work.

I've tried both methods you guys suggested, but nothing happens. The only time I could get the relay to shift, was with R.G.'s method, with the result that the pedal (TS9 in this case) turned off - e.g. flopped and the same happening with Torchy's method.

I am using a 5V non-latching relay, so what I basically need is a "switch" that connects 5V from one side to the other, when voltage is applied to it.