Simple Diode Question.  - Page 1
Forum section: electronics / beginners

author: bonifacio
author_rank: Contributor
timestamp: July 12, 2023, 08:45:14 am
content: This is just a simple project.Thought I'd give it a go and attempt to make a dry fire trainer with an airsoft pistol.When I manually activate the laser, it will show solid.When triggering it inside the airsoft pistol it's a blur.Would that mean activation from the airsoft pistol is on for too long?Since what's triggering it is a burst of gas. Just want to confirm I am going about this correctly.It's a laser diode, batteries and a clicky switch housed in a brass tube.That tube sits inside an aluminum tube. Since the brass it exposed it could be grounding inside the aluminum. Could that cause longer activation?I tried adding a buffer. Tried to absorb some of the impact. Think it could reset the button quicker.Also tried stiffening the spring.So if it means turning off is delayed, I could see about adding porting to release the gas faster.Just wanted to make sure on the technical side, if it meant the laser was activated too long causing the unwanted effect.Parts:Laser should look like this:What's happening as is now:https://www.youtube.com/shorts/VD_CoTFFuEw

author: RoGeorge
author_rank: Super Contributor
timestamp: July 12, 2023, 03:14:01 pm
content: From the video, it looks like the wiggled red line seen on the wall (instead of a dot) is caused by the recoil. Recoil moves the laser spot on the wall.I would try to turn the laser on for a shorter time. Ideally will be to turn on/off the laser shortly, just before the compressed air start to shake the airsoft pistol, when there is not much recoil by just pressing the trigger. By the time the compressed air starts to flow, the laser should be off already.Saying that because I assume most of the recoil comes from the violent air burst, and not from squeezing of the trigger, but I know nothing about airsoft, so I might be wrong. No idea how to trigger the laser go right before the air. To adjust the on time, I would use an electronic timer, for example a 555 connected as a monostabile (to produce a single pulse of controlled duration for the laser diode), something like in this schematichttps://www.circuitbasics.com/555-timer-basics-monostable-mode/The link is first result when searching for555 monostable LED, I didn't test that circuit in practice.

author: Veteran68
author_rank: Frequent Contributor
timestamp: July 12, 2023, 04:37:24 pm
content: Even without recoil, it's quite challenging to hold a laser dot still while you squeeze a trigger. The slightest tremor will cause the laser dot to jitter around, and the motion of pulling a trigger can induce several inches of deflection, which is only amplified by distance. It's why lasers are often used to train shooters in grip and trigger control, as it takes practice and a steady hand.Add in any sort of recoil, and I would expect to see the kind of behavior your video shows. I'm not sure that what I'm seeing is due to any technical issue with the device you built. You could possibly take steps to dampen the laser's reaction to movement, but then you'd almost be defeating the purpose of a training aid, as the laser wouldn't accurately depict where the pistol is pointing at that fraction of a second.Laser dry fire training cartridges for real firearms don't suffer from recoil, because there isn't any. There is only a minor disruption caused by the contact of the firing pin on the "primer" (switch), beyond the shooters aforementioned hand movement.

author: bonifacio
author_rank: Contributor
timestamp: July 12, 2023, 06:32:22 pm
content: Thank you both for the responses. Gives me insight. Wanted to confirm it wasn't the electronic side of things.I guess there's also the switch. I couldn't find a 10mm forward clicky. So I ended up with a 10mm reverse clicky. Maybe it was modifying that that's causing it to seize inside.Quote from: RoGeorge on July 12, 2023, 03:14:01 pmThe blur is from the recoil and you have the idea right. The issue is cramming that in addition to the housing and all into the tube.Quote from: Veteran68 on July 12, 2023, 04:37:24 pmI understand what you're saying. So it has to be on the mechanical side.Before throwing together my own with parts, I was able to Mickey Mouse one together. I made this with parts from an advertising flashlight pen, laser diode and heat shrink. Just wanted to make sure it would work before buying the parts. It was a different type of switch and the activating force was much less.Here's the first model I sloppily threw together. This one worked correctly, video attached. So it must be the physical mechanical action of the switch or the cap that propels forward to hit the button.