Any idea for setting a wire open or close using a digital signal?

[yhxx]

I want to control a wire to be open or close depends on a digital output from micro-controller.
For instance, if the digital signal is high, the wire will be open, otherwise, the wire remains shorted.

The wire will be used to transfer sound signal from a MP3 player.

Can any one give me some hints? I don't know how to approach this? Should I use a logic gate or op-amp?

Thanks!

 

[FoxyRick]

You could use a 74HCT4066 for this. The chip has four independent analog switches which turn on by a control signal (from your MCU). It is very inexpensive and often used to switch audio signals.

**broken link removed**

There are other, similar choices, including chips described as specifically for audio switching, but there is nothing wrong with the 4066 if used properly.

 

[Adraen]

Hi,

Wouldn't a simple mosftet do the job ? They are really inexpensive and surface mount mosfets can be tiny if space is a factor.

 

[h_vogt]

I guess yhxx is talking about analog signals, stereo, so you will need two channels. Per channel you might use an off switch and a ground switch (to short the ouput wire), in total 4 switches.

A MOSFET is an inherently non-linear device. You would need a proper DC bias network, and still you are restricted in input voltage amplitude. So better use a transfer gate made of an NMOS and a PMOS. But then you need digital control signals with both normal and invers polarity, so some logic inverters at least.

And this is what the 4066 offers.

Have a look at the data sheet attached by FoxyRick, there is a nice small SMD package available.

 

[albert22]

You can use a small signal relay like the IM03GR that operates at 5vdc 28 mA so no driver is needed. I may be simpler and will be no distortion at all.

 

[FoxyRick]

You can use a small signal relay like the IM03GR that operates at 5vdc 28 mA so no driver is needed. I may be simpler and will be no distortion at all.

That depends on the MCU being used. 28mA is over the maximum specification for a PIC (at 25mA sink or source) for instance.

 

[albert22]

Sorry, bad example. A lower current relay as IM23GR 5V 10mA should do it.
There are relays with even less coil current and voltage. So as not to use a driver and keep current low.