Barrel mounted shot counter

[bob86]

Re: Barrel mounted shot counter

i've had in the back of my mind something like this for mid caps, counting up, not down.

the one that is linked as a kit, seems like it is switched from the trigger (why else does it need rpm and what sort of firing is being used)

i'd like a simple 3 digit counter, mounted under where a sight would be, powered off the guns battery, and using a light gate in a silencer. the chrono idea is a nice feature though.

i have no idea how large the PCB would be for this though, never properly looked into it

[Mavrik]

Re: Barrel mounted shot counter

The PCB should be relativley small as it is only a counting circuit which is relativley simple and is more or less available as a buyable product. The G&G silencer thing is sort of what sparked this idea. That and watching aliens..I think i will mount the display on a M4 top RIS rail meaning the odds of it getting hit is very small. It would have to pass through my body and if that happens i have a bigger problem . Thank you again for all of your input and ideas. They are incrediably helpful. Once again thank you.

[bob86]

Re: Barrel mounted shot counter

how do you link in a photo sensor?

[No1_sonuk]

Re: Barrel mounted shot counter

how do you link in a photo sensor?

The photo sensor provides an electrical pulse every time a BB breaks the beam. That pulse is used to trigger the counter.

[Mavrik]

Re: Barrel mounted shot counter

Exactly as the gentleman says above me in terms of the sensing, finished the start of the PCB design and have used prodesktop to make a mock up of the silencer. Hopefully soon I can start building

[bob86]

Re: Barrel mounted shot counter

thats not really what i meant... i know how they work, what i mean is, how does it connect into the circuit? its not exactly like adding a NO switch in. it needs power, is that routed thru the pcb? when its triggered does it act as a switch or does it then add a voltage to the circuit somewhere?

[No1_sonuk]

Re: Barrel mounted shot counter

It's hard to give more detail without doing the design work.
Check out post#4 here for a simple circuit:
http://forums.bit-tech.net/showthread.php?t=160152

[Mavrik]

Re: Barrel mounted shot counter

A sorry I get what you mean, the LDR allows the resistance to drop to allow a current to flow, this sends a blip to the PCB and the counter to the decoder. The counter and decoder are part of the PCB and the current does flow through the PCB.

[bob86]

Re: Barrel mounted shot counter

thanks, im more mechanical than electronic i've found a prox sensor in one of the spares kits i have in the boot for work, gonna see if that will detect a bb, or if its a metal only detector. failing that, i also have a SICK micro type, reflect sensor, might see if that works on bbs

[No1_sonuk]

Re: Barrel mounted shot counter

A sorry I get what you mean, the LDR allows the resistance to drop to allow a current to flow, this sends a blip to the PCB and the counter to the decoder. The counter and decoder are part of the PCB and the current does flow through the PCB.

Umm. Yeah. I think.
Sorry, I'm an electronics engineer, so this sort of thing is simple for me to do, but hard to break down any simpler.

thanks, im more mechanical than electronic i've found a prox sensor in one of the spares kits i have in the boot for work, gonna see if that will detect a bb, or if its a metal only detector. failing that, i also have a SICK micro type, reflect sensor, might see if that works on bbs

If the proximity sensor is a closed cylinder, it's for metal only.

A reflection sensor might work if you get the position and alignment right. The pulse might be shorter than the beam break type, though, and you'd need to be careful about the "view" - If the sensor is in a position to see it's own reflection because of a reflective surface in the tube, you might need to detect the BB's "shadow", rather than the reflection caused by it passing closely.

It's all dependent on the exact type of sensor, and how brightly you drive the LED.

On that note: The LEDs in such sensors are usually infra-red (IR) - you won't be able to see it with the naked eye.
If you want to check that it's on, try using a video camera of some kind (a phone camera might work too). They can usually see IR, and so you can also check if your TV remote is working.

Also remember some things that are opaque to normal light, might not be to IR.

[bob86]

Re: Barrel mounted shot counter

thanks sonuk, gave it a go last night, yeah the prox is a metal type, so no good for this.

the beam break reflector type sensor was promising, but didnt seem to pick up on the bbs, either they were too fast for the sensor to pick up on it, or my multimeter is too slow to register it. also the bbs were reflecting the beam, so looks like its either a micro switch in the hop, or a ir breakbeam....

also, the sensor is a nice design, with visible red dot for alignment so was easy to check

[No1_sonuk]

Re: Barrel mounted shot counter

A multimeter is WAY too slow for that.
You'd need a storage oscilloscope to catch something that fast.

[Chas]

Ok a few ideas, why not make the number it is counting down from adjustable so that you can set it your mags capacity and then rig it to the battery and use it to stop the gun dry firing when you are out of rounds. You would have to reset it every reload, but hey

[Mavrik]

Re: Barrel mounted shot counter

Ater some discussion with my electronics teacher apparently an LDR is not fast enough, it takes a couple of seconds for its resistance to drop when the light level drops so instead i need a photo transistor which does it much quicker and a device called a schmitt trigger which means that any change in voltage will be converted to a logic high or low depending on wether the voltage goes up or down. That means the voltage only needs to change a little for the pulse to be sent which speeds up response time

[No1_sonuk]

Re: Barrel mounted shot counter

WRT parts: If you have an old computer mouse (the type with a ball), you can salvage 4 IR LED and detector pairs.
Whether the detectos are phototransistors or photodiodes you'll have to try to determine (might be possible to tell from the PCB legend).