# Electronic Circuits and Projects Forum

1. ## Quick question

I'm completely new to this world of electronics. Not that I don't use them, but to the whole building it from scratch...

Anyway... What I'm trying to do is take the electric signal from my headphone wires and make that signal run some LEDs. But the strength of the signal isn't strong enough to make them light up.
So is there anything out there that could amplify the signal or something? Or something that would make the lights turn on, but the lights would use power from an external source?

2. There are ready-made devices that can do this, or you can build it yourself. You're correct in thinking that some kind of amplifier (or switch, more properly) is needed; the headphone signal isn't strong enough to light LEDs directly.

What electronic skills do you have?
• Being able to read a schematic (this is essential, and not rocket science)
• Looking up stuff on-line or in the library

3. Try this:

4. My electronic skills are pretty much knowing how to solder and follow directions haha. But I'm wondering if there was something that would work like I have in the picture It would use the electrical signal to tell the LEDs to light up on an external power source, like a small battery of some sort.

5. It looks as if you have plenty of room for the circuit that Colin posted. All it is is a couple transistors and a few resistors. You'd need to use a small battery, like a coin cell. Doesn't look like enough room for AAAs.

By the way, your picture is waaaaaaaay too big. Be nice and resize!

6. Isn't his circuit to plug in and be plugged into with the TRS jacks? How could I get it to work inside each headphone?

7. I don't know what that circuit board inside your headphone is, but all you need to do is connect his circuit to the wires coming into the headphone. Just find where they connect to that circuit board, and solder wires to those connections. (The incoming wire to the headphone, not the wire to the headphone speaker element.)

8. It's just a volume adjuster, it could be taken off to make some room in there.

9. So all you've got to do is connect the incoming line, the headphone element and the input to Colin's circuit all in parallel. Be careful not to reverse the polarity of the headphone element or they'll sound weird! (Or not: does anyone know how the human hearing system responds to out-of-phase signals?)

10. Out-of-phase speakers cancel bass frequencies. Hi-Fi stores ALWAYS had the speakers connected out-of-phase then the bass tone control was turned up to maximum to try to make some bass. I always re-wired them properly and turned down the bass tone control to normal.