Power in a signal circuit

[LukeeeeBennett]

I was wondering how I could put a DC battery into a circuit that takes a AC signal. I need the DC as it will power LEDs that will turn on when a switch is engaged. But obvious if I just place it in with the signal input, it will just shift all of the signal AC up 9v (Or whatever voltage supplied).

So, is there anyway to do this?

 

[carbonzit]

So you're trying to use the same line for both an AC signal and DC power? Why? Why can't you use a separate line to power the LEDs?

You might be able to power the LEDs by rectifying (and filtering, if necessary) the AC out, but it'd be kind of a Rube Goldberg scheme (overly complex solution to a problem, if you're not above a certain age).

 

[Sceadwian]

Can you post a schematic of the circuit you're trying to alter?

Carbonzit, it's not a rube goldberg scheme, both telephone and some cable systems still provide a DC bias above ground on the signal line for powering devices connected to it.

 

[ronsimpson]

What AC? 60hz? Audio?

 

[carbonzit]

Carbonzit, it's not a rube goldberg scheme, both telephone and some cable systems still provide a DC bias above ground on the signal line for powering devices connected to it.

I know that's done. I meant it would be Rube Goldberg in the sense that if the O.P. could simply run another wire to the LEDs, they could avoid having to separate the power from the signal in the first place.

 

[ronsimpson]

I have run power and video on the same wire. The video source and receiver need to be AC coupled with a capacitors. (high pass filter) The DC supply and DC load should be decoupled from the wire with inductors. (low pass filters)

 

[LukeeeeBennett]

OK, So here's the schematic.

**broken link removed**

The signal generator on the left is just going to be a guitar input. The example is how I want an LED on each switch. So when a switch is on, the LED is on.

 

[Reloadron]

While I don't fully get what is going on with the circuit you could likely save some headaches and rather than use SPST as shown use DPST switches dedicating one pole to the LED.

Ron

 

[LukeeeeBennett]

While I don't fully get what is going on with the circuit you could likely save some headaches and rather than use SPST as shown use DPST switches dedicating one pole to the LED.

Ron

Using a DPST would mean it turns on when the switch isn't on the right path, unless I used a transistor, which I was trying to avoid to keep costs low.

 

[4pyros]

Using a DPST would mean it turns on when the switch isn't on the right path

No thats SPDT, Single Pole Double Throw
You need DPST, Double Pole Single Throw

 

[LukeeeeBennett]

No thats SPDT, Single Pole Double Throw
You need DPST, Double Pole Single Throw

Ahh yes! Sorry Reloadron. :3 Silly moi.

 

[LukeeeeBennett]

Okay, all is sorted now, thanks a lot Reloadron and 4pyros. Now just to find some DPST footswitches... That are cheap. :| Hahaha.

 

[Reloadron]

Like the attached DPST. Each LED is a separate circuit. When switch is closed your signal is passed and LED illuminates.

Ron

 

[LukeeeeBennett]

Thanks buddy. I think I'll end up using DPDT switches as latching foot switch in a DPST config are a huge annoyance to find at a decent quality/price. ^^

 

[carbonzit]

I'm still not entirely clear on how this would have worked, but I think your original scheme was to carry both the guitar signal and the LED voltage in a single circuit, with the guitar presumably going into the input of an amplifier, correct?

While you could have made that work, another problem would have been a tremendous "Thump!" out of the amplifier every time you switched inputs. You could probably have filtered it out somehow, but as I said earlier, it would have been something worthy of Rube Goldberg. The double-pole switches are actually a much more elegant solution.

 

[LukeeeeBennett]

I'm still not entirely clear on how this would have worked, but I think your...

Yeah you're right, it's just previous clones I've seen have carried the LED power and signal on the same line, but I much prefer this method.

 

[4pyros]

it's just previous clones I've seen have carried the LED power and signal on the same line,

What are you trying to clone?

 

[LukeeeeBennett]

What are you trying to clone?

I'm not, I'm building my own simple pedal circuit, but I've seen it with previous clones.