Touch button questions

[idi]

Hi everyone

I have a question which i need a little advice on.

I have a set of speakers for my computer which have touch buttons for the volume. There only seems to be one wire going to each button.

The speakers are placed at the other side of the desk (large desk) so i cant reach them each time to control the volume.

I wanted to extend the controls so i can move them closer to me. I attached a wire to each touch control on the speaker to test it, and as soon as i touch the wire on a button, it has the effect that the button is being pressed and held so the volume shoots up or down. This is without me touching the other side of the wire.

Why is this happening? is there any way i can extend the the controls without this?

Thanks for the help in advance

 

[grantr37]

can you take a photo of the inside of the speaker/the switch connections and put it on here?

 

[idi]

The speakers are clear, so i took a picture of the connection inside without having to open them

Front View:


Side view: (connectors visible)


Thanks

 

[telectrix]

looks like 2 connections to each button, a brown and a grey. that would be logical.

 

[idi]

looks like 2 connections to each button, a brown and a grey. that would be logical.

Theres only 1 connection to each button. the brown wire in the picture is the wire for the other button

 

[Nimbus265]

Single wire would indicate that they are capacitance touch switches - i suspect the switch itself is metalic? They work by using the human bodies capacitance to change the base current in a highly sensive amplifier (works at the level of pico amps) which is used the increase or decrease volume. Very difficult to extend, as the total impedance of the circuit Z= ( R+Xc) is very highly tuned. Adding even a small length of wire adds to R, which changes Z, which changes the drive current for the volume amplifier.

 

[Nimbus265]

Some bedside lamps work on the same principle!

 

[idi]

Single wire would indicate that they are capacitance touch switches - i suspect the switch itself is metalic? They work by using the human bodies capacitance to change the base current in a highly sensive amplifier (works at the level of pico amps) which is used the increase or decrease volume. Very difficult to extend, as the total impedance of the circuit Z= ( R+Xc) is very highly tuned. Adding even a small length of wire adds to R, which changes Z, which changes the drive current for the volume amplifier.

That makes more sense now. Is there any way to extend it then?

 

[Nimbus265]

To be honest, I doubt it. I suspect it will be a reactive switch; capitative is most common but it could aslo be an inductive reactance switch or a pizzo switch. You'd be into circuit redesign I suspect. You could try wiring a variable resistor in series with the audio supply cable and remoting this to where you are sitting. You could go further and wire a matched impedance (4/8/16 Ohm) potentimeter across the input if you are bothered about impendance matching. I'd be inclined to try a simple varaible resistor from somewhere like maplins on the input. You won't bugger up the speakers by restricting the audio signal to the speakers (set the speakers volume high then adjust volume with in-line variable resistor). Just a thought

 

[idi]

To be honest, I doubt it. I suspect it will be a reactive switch; capitative is most common but it could aslo be an inductive reactance switch or a pizzo switch. You'd be into circuit redesign I suspect. You could try wiring a variable resistor in series with the audio supply cable and remoting this to where you are sitting. You could go further and wire a matched impedance (4/8/16 Ohm) potentimeter across the input if you are bothered about impendance matching. I'd be inclined to try a simple varaible resistor from somewhere like maplins on the input. You won't bugger up the speakers by restricting the audio signal to the speakers (set the speakers volume high then adjust volume with in-line variable resistor). Just a thought

I've managed to extend it about 30cm using speaker wire and it still works. Will it make a difference if i use a thinner wire to extend it?

 

[Nimbus265]

I've managed to extend it about 30cm using speaker wire and it still works. Will it make a difference if i use a thinner wire to extend it?

Nothing to lose!:walkman: