Matrix Orbital Corp

So there are a number of posts and articles about running how powered components (CCFL lighting, fans, etc.) off of low powered GOPs, but what I need is something on the other end of things.

I don't know much about elctronics (I've only taken an intro level EE course), but what I need to do is control the keypad inputs using voltages, not switches.

That is, when I push a key, I get 5v at a max of 1 ma and I need that to trigger the keypad input...I will have six of these. I know this must involve transistors, but I'm not sure how (especially since I don't know exactly how the keypad interface works)

Any help would be much appreciated.

~Adam

Okay...now I'm not a king in electronic but it will be something as you will start with your 5v - 1mA and ramp up a little to about 5v - 150mA with a simple transistor and next, you use a relay to contact the keypad input...
but you can't keep the contact close. ex: you cannot press two keys at the same time....

The way the keypad works is that on one pin you have V+ and the other pin is GND...when you switch V+ to GND a keypress is made... But, the keypad interface work as a matrix of row and colomn...just check the MO site to have better explanation of the Keypad connection...

You want the 4066 quad bilateral switch, or one of it's relatives. when it gets a logic HIGH, it closes a switch (actually turns on a couple FETs), so it's ideal for interfacing logic level signals to the keypad headers.

Cheap too, I think I paid $0.25 for mine.

*Tip of the hat to Stig for coming up with this in the first place.

I agree with Linear....

very interresting piece of electronic here....easy to use too!

Ah huh...I saw the 4066 mentioned elsewhere in the forum, but the datasheet link is much appreciated as I couldn't find it before. I knew there must be something out there, prepackaged, that does exactly what I need.

BTW, in case curiosity springs up, I'm interfacing with aQT160 (just got a few yesterday and it was a sinch to get working)...very cool.

Thanks Man.

~Adam

EDIT:
Oh yeah, what is TTL and do I need / want it (I noticed there is a TTL enabled version and a normal version...)

Try this link: http://www.philipslogic.com/products/switches/4066/

Very cool app. by the way...you might have to post some pics in our gallery when done...!

TTL -> transistor-transistor logic, usually meant to indicate +5V corresponds to ON. As opposed to RS-232 or some other signaling scheme where other voltages mean ON or OFF.

QT113H-D was the ones I used. They are active high, so I could close a 4066 directly from the output, no inverter required. Most of the QT11x are active-low. Looks like the 160 is active-high, so you're good to go--that's a new product since I got mine. You're right they are pretty easy to deal with. Be sure to shield the connection to your electrodes and ground the shield.