You've likely seen these 4 button keypads on ebay, ali-express, or elsewhere, usually either blank, or with buttons labeled 1,2,3,4. Nice for experiments, but...

"1 2 3 4" is just not very useful!

So after long consideration, I decided on some better labels for a 4 button array, to make them much more instinctive to use in a variety of projects. With a little imagination and some clues from an LCD screen or serial output, you can hopefully see where these are MUCH more useful for programming settings in a project, which you later can save to EEPROM or other non volatile memory. As a bonus, the button array has a peel-away backing with some very strong adhesive.

Note that these key pads were custom printed for Elfin Technologies, so they currently are NOT available anywhere else. As you can imagine, we had to order a LOT more than we'll need to have them made, so we're making them availble for everyone. For any "bulk orders", please write for consideration of additional discounts.

A boost regulator is an electronic device that will supply a constant voltage, with an input voltage less than (or equal to) the output voltage. This one can be adjusted to output any desired voltage between 5V and 24V, at about 2A maximum, with an input down to about 2V. These are the boost converters used in our DIY project, Battery life extender for guitar pedals. Definitly read that article for a better description of a practical application, caveates, specifications, and usage. Package prices are offered there too for added components, but here the converters themselves are offered as a stand-alone item.