The first step was to see if I could make a trigger that would detect a pellet. A trip to the local Radio Shack and I had my phototransistors. I had the LEDs in my parts stash along with some transistors to make a latch that would keep an LED lit if the photo-transistor detected the pellet. I built the circuit on a breadboard and mounted my "pellet detector" on a target built with a 1X6 with washers over holes drilled in the board. It took some tweaking and tinkering but I was able to get it to sense a pellet passing between the LED and photo-transistor.
This is an old target, originally it had pieces of pipe hanging behind the holes that would "Ring" when the pellet made it through the hole in the washer. I removed the pipes so I could use the target to build my Proof of concept pellet detector.
The LED and Phototransistor are taped to the back of the target and lined up across the hole. The latching circuit is on the breadboard. It's powered by a 9 volt battery.
It took some tweaking and cussing but I got it to work dependably. The sensor is behind the lower right target. when the pellet passes through the hole it turns on an LED next to the target.
Now that I know I can detect the pellet I will move on to the next phase, building a target that lights up and makes noise. I'm thinking a green LED for a successful shot and a buzzer for a miss...
The next version should be a bit more finished looking.
UPDATE - PHASE II
I made up another target with one 1/2 inch target and one 1/4 inch target. I used a yellow LED to indicate a good shot on the larger target. I used green LEDs to indicate a good shot on the smaller top target. The LEDs are mounted in a piece of Lexan on top of the target.
The backside of the target is less than clean..... This is just for fun, and making things tidy isn't much fun.
I have a circuit bread boarded to indicate a miss. It uses a piezo pick up to pick up vibrations through the board the target is made from if a pellet hits it instead of making a clean pass through the hole in the washer. A miss lights up a red LED and starts a buzzer. I made a short video of the target, the buzzer is hard to hear in the video but it works.....
This video shows the target in action. I'm pretty happy with the results, it lights up and makes noise. I'll have to get the buzzer circuit on a circuit board and mounted permanently before I call this project done. in the video the bread boarded circuit is sitting in front of the target so you can see the LED light up.
I was out of white LEDs so I used a red one for the bottom target, you can see the red glow through the lower target.
If a pellet clips the washer but still makes it through the hole in the washer the LEDs still light up but the buzzer will go off also letting you know it wasn't a perfect shot....
