Airgun silencer part 3

this continues fromĀ part 2.

I ordered a Schmitt Trigger 3-input AND gate. It has a nice and wide Vcc input range (1.65V – 5.5V) and is nice and fast (max 4.1ns @3.3V, and faster (around 2ns) @ 5V) and coms in a nice small 6-pin SOT23 package.

I connected the outputs of the OPL550 phototransistors to inputs A & B respectively and input C to Vcc. Now I have a 3pin interface.. Vcc, GND and the output that has the 2 pulses…


Here we can see the output of my TDR (a 12 ft-lbs gun), shooting a H&N Sport Baracuda (10.65gr) at around 722fps (the sensors are 50mm apart in this prototype)


Next to get it into the micro and out of the USB port…

…continued on part 4