Hello,

I have a question regarding switches. As part of my dissertation research, I need to hook up a pulse stimulator and an EEG machine to a test sample. I need to be able to switch back and forth between applying the stimulus to the sample and then recording an EEG reading from the sample. I don't necessarily need to record the EEG during the application of the stimulus, but I need to be able to switch back and forth very quickly. The stimulus only lasts 1 sec, and I need to be able to record an EEG both before and after.

I have a positive and a negative lead coming from the test sample, the pulse stimulator, and the EEG machine, so I am guessing that whatever sort of switch I use needs to have places to hook up 6 wires.

I'm pretty much learning about electronics as I go along on this project, so any help you could give me about what type of switch I need, how to hook it up, etc, would be greatly appreciated!! If I've left out any important details, please let me know--I'm not sure what's important and what isn't

Thank you!!

 

Are you looking for something automatic or manual?

 

Do the EEG and pulse stimulator have control interfaces (GPIB, USB, etc.) that you could connect to a computer? If you're trying to do this automatically you'll need some way to trigger the pulse stimulator and the EEG.

 

Thanks for the replies!

Bill--At present, anything that will work is fine with me I had envisioned it being manual though, mostly because I thought that would be simpler for me to set up.

Roddefig--I don't believe either of them have any sort of interface to connect to a computer. So that may feedback into Bill's question, and limit it to manual..?

 

You could probably get a telephone switch box or data switch box fairly easily, just connectorize your wires and label the front. More than enough wires and positions.

If you need something more sophisticated don't hesitate to ask.

 

Thanks Bill! I'll give that a try today and see how it goes. Thanks for all of your help.

 

6 Wires huh

That's lucky

The standard rotary switches have 12 positions and come in the following flavours

1 pole 12 way
2 pole 6 way
3 pole 4way
4 pole 3 way
6 pole 2 way


Each pole is a switched wire, so you need a 6 pole 2 way switch. As your medical physics tech or college radio/electronics workshop to put one in a box for you with some terminals.

cheers

 

That is a very slow and reliable way to go. If the switching has to be done with better accuracy as to time and duration, something like analog switches will be more like it.

To Uscgirl - is the switching simply to isolate the EEG inputs from the stimulus? How is the process controlled? If we know everything, then we can give much better advice.

 

Thanks for the replies!

studiot--Good tip about the rotary switch. I looked those up online and they look like a really good idea. I'll ask around at the machine shop and see what they can do.

beenthere--I am hoping to use the same bipolar electrode in my sample for both recording and stimulating, so i need to be able to switch back and forth between using it to record and using it to conduct the stimulus. So I want to be able to use the electrode to record EEG activity, then flip a switch and use the same electrode to apply a stimulus, then flip the switch again so that I can record more EEG activity. I'm not sure if that exactly gets at the answer to your question though, so if not, just let me know and I'll try to describe it better.

 

Something else that may do the trick for you is a manual parallel (printer) port switch (not an electronic one). Your computer support department may have some sitting around. You will need DB25 male and female connectors to hook things up.

 

The thing that makes one method work and not another is twofold - timing and the magnitude of the stimulus. Can you quantify them?