Fairly simple traffic light controller I built the other day. It consists of 5x relays switched using a ULN2803 darlington array with free wheeling diodes from an Arduino. Two digital inputs are also available to hook buttons up. 12V/DC power is supplied using a 230V/AC PCB SMPS module. Not too much to say about it really.
I got this old camera photometer a while back and it wasn’t working, so I figured let’s see what’s wrong with it. Turns out the photocoll just wasn’t making good contact, I rotated it slightly ~45° and the meter started working again. The fotocell is dated 26. March 1935. Links Tempophot - Antique and Vintage Cameras Tempophot T-4
Circuitry Overview The circuit is super simple, there is a motor run capacitor for the AC fan which is connected to a separate tap on the transformer and insulated from the rest of the circuitry. A small triac dimmer on the secondary 12V AC side using a MAC223 triac and another 3 pin TO-92 device which I think is either another triac or a SCR two film capacitors and a couple potentiometers.
Putting some bench grinder wheels under the microscope, here is a selection. I may update this post as I get new ones or also add some older/used ones I have sitting around. Picture Grit Type Manufacturer 36 NK Manufacturer 1 36 NK Manufacturer 2 60 NK Manufacturer 1 60 NK Manufacturer 2 60 EK Manufacturer 1 80 SC Manufacturer 1 80 SC Manufacturer 3