Low key count membrane keypads

[AndrewC]

Anyone know of a cheap source for 3 or 4 key membrane keypads ? It is easy enough to find expensive ones from parts suppliers but I can't find anything on eBay. Or to look it it another way, if you had a project that only needed 4 keys for data entry, is there a more elegant way than 4 push button momentary switches drilled through the front panel ? The most elegant is undoubtedly a touch screen GDU but I'm not going that way - yet !

Andrew

[aratti]

Andrew, you can disassemble a piezo buzzer and use the internal as a pushbutton. Just connect the two wires one to ground and one to the input (better if you protect the input with a zener) use the DT interrupt routine and you will see the piezo element switching your interrupt all the time you press it.

Mind the polarity.

Al.

[mister_e]

Tact switches mounted on a pcb, some hole on the front plate, and a home made (or any other much fancy place) membrane to stick over the whole thing (front-plate). Neat enough, cheap enough, easy to repair/modify too.

[AndrewC]

Andrew, you can disassemble a piezo buzzer and use the internal as a pushbutton. Just connect the two wires one to ground and one to the input (better if you protect the input with a zener) use the DT interrupt routine and you will see the piezo element switching your interrupt all the time you press it.

Mind the polarity.

Al.

Now that sounds interesting.

[AndrewC]

Tact switches mounted on a pcb, some hole on the front plate, and a home made (or any other much fancy place) membrane to stick over the whole thing (front-plate). Neat enough, cheap enough, easy to repair/modify too.

Scary parallel processing - I've got a piece of scrap PCB at home with a tact switch covered with some clear silicone which is drying. I'm hoping the silicone will have not penetrated the switch but will provide a flexible enough seal over it.

Andrew

[falingtrea]

Check out this keypad (http://www.sparkfun.com/commerce/categories.php?c=145) at Sparkfun. It is a silicon 2x2 with LED backlight. Kinda neat and you can build up other key matrixes using the parts. They also have 4x4, a 3 button gamepad like, and a 12 key membrane. The 4x4 can be cut in half to make 2 2x4 pads.

[AndrewC]

Check out this keypad (http://www.sparkfun.com/commerce/categories.php?c=145) at Sparkfun. It is a silicon 2x2 with LED backlight. Kinda neat and you can build up other key matrixes using the parts. They also have 4x4, a 3 button gamepad like, and a 12 key membrane. The 4x4 can be cut in half to make 2 2x4 pads.

they've got some nice keypads there - thanks :)