Digitally controlled circuit connecting

[beakie]

Imagine a 5v circuit which has a switch on it. When that switch is pressed, I want to close the circuit, when it isn't I want the circuit to be broken.

OK, what I am looking to do is replace the switch with some sort of component that can be controlled by a pic chip. I want to pass a voltage out of a pin from the pic and have the circuit connected. I dont want to pass a current to the circuit, just to connect it.

What (component) do I need to achieve this please?

 

[MikeMl]

How much voltage/current does your external load draw? Is one end of the load grounded?

 

[beakie]

How much voltage/current does your external load draw? Is one end of the load grounded?

It's for a digital camera so it will probably be 5v or similar. I thought about supplying the 5V instead of shorting the 2 pins on the camera, but I am afraid to. It's an expensive camera and more importantly... not my camera. I would prefer not to put any form of voltage into the camera apart from that which the camera itself is supplying.

Cheers

 

[MikeMl]

The problem is that any non-opto isolated switching scheme requires a shared ground between the controller and the camera, meaning you will have to figure out something about what is in the camera. Is that what you are trying at all costs to avoid?

Are you opposed to using a miniature relay?

 

[crutschow]

As Mike MI suggested, use a relay which will give complete isolation. You would need to add a simple transistor amp (one NPN transistor, one resistor, and one diode), controlled by the PIC, to drive the relay coil.

 

[beakie]

As Mike MI suggested, use a relay which will give complete isolation. You would need to add a simple transistor amp (one NPN transistor, one resistor, and one diode), controlled by the PIC, to drive the relay coil.

Thanks to you both for your replies.

Can you point me at some literature online relating to this technique? Would like to have a read on the subject but can seem find the right words to google.

Thanks!

 

[crutschow]

Here's a short tutorial on transistor controlled relays.

 

[Wade Hassler]

Thanks to you both for your replies.

Can you point me at some literature online relating to this technique? Would like to have a read on the subject but can seem find the right words to google.

Thanks!

Google

.. note the first hit: local boy makes good!

 

[beakie]

Superb. Thanks to all that took the time to reply!