Tonight at NERP, Yours Truly will show a couple of ways to interface from low level logic to 120VAC to control lights, motors, etc.
It’s well understood that small microprocessors have very little power available on their output pins. A load controlled by the processor can be AC or DC, and low or high voltage. The interface circuit has to amplify the logic level signal to the appropriate power for the load. An unusual method (Ok, it’s a hack) for controlling 120VAC light dimmers involves adding a photocell to a commercial wall dimmer, and coupling the photocell to the processor via a PWM’ed LED. (This method of interfacing involves working with dangerous voltages and currents. It is presented for demonstration purposes, only. Don’t try this at home. Or do. It’s your choice.) A simpler method of interfacing to 120VAC uses solid state relays for on-off control. We’ll see SSR’s used for making a big blinky for large lamps.
NERP is not exclusively raspberry pi, the small computer interest group at Pumping Station:One in Chicago.
Find NERP and Pumping Station:One
at http://www.meetup.com/NERP-Not-Exclusively-Raspberry-Pi/
and https://pumpingstationone.org/
NERP meets every other Monday at 7pm at Pumping Station:One, 3519 N. Elston Ave. in Chicago.
Doors open at 6:30pm. The next meeting is Nov. 18, 2013 NERP is free and open to the public.
Ed Bennett ed @ kinetics and electronics com
Tags: electronics, embedded, NERP, Open Source, raspberry pi, hackerspace, Beagle Bone, Element14
