Friday, July 25, 2014

Constant Current, or Constant Voltage?

I needed a Constant Current power supply for my bench. Now I don't know if you have priced bench power supplies lately, but they can be several hundred dollars. Not any more! Would you believe a 40v 3a adjustable voltage or current supply for about $20?
I grabbed a used 24vac HVAC transformer, soldered a bridge rectifier on top, and fed the input on this board. I put a 300ma 1w LED on the output, and I'm controlling the brightness by controlling the current, even down to 2ma (dim), all the way up to 300ma (blindingly bright). I could go higher, up to 3000ma, but that will let the magic smoke out.

Wednesday, July 23, 2014

Put the Physical into Physical Computing!

The whole point of microcontrollers and physical computing is doing something with the data sensed. If you sense a temperature, if you sense motion, you act on it. However, There's a bunch of science involved when you want to make things move, making sure you have enough power to move said object. The best explanation of the science of making things move is "Making Things Move DIY Mechanisms for Inventors, Hobbyists, and Artists" by Dustyn Roberts.
I've written about this book before, and I own it in paperback and kindle version, because it's that important to Arduino and Raspberry Pi owners. If you want action, you need this book. It simplifies the "magic" of making your microcontroller make things move, in some cases, very large objects.