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Topic: Close keyboard contacts from Arduino (Read 1 time) previous topic - next topic

xovez

May 26, 2013, 03:12 am Last Edit: May 26, 2013, 01:59 pm by xovez Reason: 1
Hi!

I need to control a system wich have a keyboard from Arduino, simulating the push of its keys.
How can I close the contacts of the keys from Arduino? Using an optocoupler?

I do not know if I can use an optocoupler, and if where possible, wich model to use.

Note: I measured that when I push a key in the keyboard, its contacts aren't closed with a 0 Ohm resistence, but they are closed with about 55-75 Ohm.

Any ideas? schematics? Has anyone tried it?

PD: I attach a picture the keyboard contacts

Thanks!

Osgeld

what voltage is the device

could use a transistor, collector on non common pad, emitter on ground, 1k to base with the arduino on the other side

xovez

Thanks Osgeld

The device voltage is about 3.5v - 5v.
You suggest a simple NPN ? like a 2N2222???

The common pad is not ground. The pads make a matrix with common on columns and rows (like the attached image).

Your suggested solution can work properly anyway?

CrossRoads

Or a bunch of little relays. Here's a 1284 driving 15 relays, design had 18 originally, 3 were removed for some other expansion.
USB and RS232 interfaces.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

xovez

Thanks CrossRoads for your suggestion. Simple to develop, but my circuit must be installed inside other device and I haven't space to place about 14-15 relays :)

I readed the datasheet that sais Telecommando, the CD4066. Seems an interesting solution, but for simplicity and availability of components in my city, I prefer using a few simple optocoupler. Do you know any recommended model? Can it be a valid 4N35 or TIL116?

Thanks!!!

Osgeld

given your image you could do it with 16 transistors, theres a common ABCDE and 1234

given the jack squat current configurations for this type of layout you could accomplish it with a transistor array in a dip format

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