A Design Challenge

[Overclocked]

First See Pic. No, Its not a real gun, but rather a BB gun I bought myself. Obviously enough it Looks Kinda SciFi-ish. So To make it more cooler, I thought of adding a Ammo Counter using 2 Seven Segment Displays. I have thought of 2 ways; One involves Using a Optical Sensor on the Trigger and the 2nd Involves some kind of sensor on the end of the barrel (probably capacitive- However The End of the Barrel is pretty thick about 1/4 inch. The Gun uses Lead Pellets, Not steel BB's). The Trigger Pulls all the way back to where it ends when firing.

Any Other suggestions? I have the counting circuits mentally figured out, Its just How to sense when a Pellet is fired. The Clip can hold 12 Rounds. To reset the counter when I am finished, I figure just press a button some where hidden on the rifle.

And Id rather not take it apart either...Oh, Its also Semi Auto and almost no recoil

And if your also wondering where everything is going to be mounted, The LED display will be mounted Just behind the Rear Sights, and the Circuitry (which will be SMD) will also be housed there. The battery will be housed in the butt of the gun (probably will be those small round batteries that go in laser pointers)

 

[agg_asd]

Transformerless power supply w/ 12VDC @350mA

Hi Guys,

Can anyone help or send to me a schematic diagram of transformerless power
supply with 12VDC @ 350mA regulated output. my email is agg_asd@yahoo.com.ph

 

[k7elp60]

I once did a countdown counter for a paintball gun for a individual. The initial count is programable with dip switches and the trigger was an impulse from a switch and my circuit has debouncing. It uses an LCD display, but if you change the 4543's to 4511 you could use LED's. Would you be interested in the schematic?

 

[Overclocked]

I once did a countdown counter for a paintball gun for a individual. The initial count is programable with dip switches and the trigger was an impulse from a switch and my circuit has debouncing. It uses an LCD display, but if you change the 4543's to 4511 you could use LED's. Would you be interested in the schematic?

But where was the switch Located? How did the count go down each time the Trigger was Pulled? Sure PM me with the schematic.

 

[k7elp60]

But where was the switch Located? How did the count go down each time the Trigger was Pulled? Sure PM me with the schematic.

I don't recall where the switch was located its been a couple of years since I built the thing, and he had the switch mounted and all I did was supply the counter. My counter uses some 4510 programable U/D counters that is initially loaded with the amount of projectiles, and each time the switch is closed it counts down. Then has one pushbutton to reset the counter.

It is possible that you could mount a small microswitch right next to the trigger so that each time the trigger is pulled the switch would close. There are multiple microswitches with different levers for actuators.

It may take me a couple of days to find the schematic of my counter. I can PM it to you in jpg or pdf format.

 

[Salgat]

Couldn't you just mount a small push button behind the trigger?

 

[Roff]

How about a tiny rare earth magnet glued to the trigger, and a Hall effect Schmitt trigger behind it?

 

[Overclocked]

Couldn't you just mount a small push button behind the trigger?

I think thats what k7elp06 was suggesting, that would work, but what if the trigger doesnt go back all the way during rapid firing? eg, w

How about a tiny rare earth magnet glued to the trigger, and a Hall effect Schmitt trigger behind it?

I like that idea! Everything is going to be attached Via Velcro, So it can be taken off if needed. Hmm, I could do the same for the reset switch since the cover for the clip slides back and forth, I can use the same concept for that (to get to the clip you have to slide the cover open and then slide it closed- This way when its open Reset is always activated So then if someone were to falsely trigger the count, it wouldn't happen)

This seems suitable enough
https://www.mouser.com/search/Produ...-PL-Avirtualkey62110000virtualkey811-ATS137PL

 

[Roff]

You might also want to look at This **broken link removed**. It appears to be less expensive, and is more sensitive (which might be good or bad, depending on your magnet). Of course, you would want to consider the cost and availability of other parts, shipping costs, etc.

 

[Overclocked]

You might also want to look at This **broken link removed**. It appears to be less expensive, and is more sensitive (which might be good or bad, depending on your magnet). Of course, you would want to consider the cost and availability of other parts, shipping costs, etc.

The only thing I dont have is a small enough magnet. I have magnets from microwaves and HDD's, but nothing smaller. I guess if worse comes to worse, I can always Chop a chip off and use it..or maybe a piece of magnetized iron will do. The actual clearance between where the trigger ends and where I want to mount the sensor is very small, maybe 1/4 of a inch or less

 

[Roff]

You can buy **broken link removed**. There are many sources. Google is your friend.

 

[Overclocked]

You can buy **broken link removed**. There are many sources. Google is your friend.

Oh yes I know that, But I cant buy them from Jameco or Mouser is what I was saying.

Wait! The local craft store sells magnets and Im going to walmart tonight (they have a craft section to)

 

[2camjohn]

How about picking up the sound of the gun firing?

I guess the sound is quite specific, and this method reduces any interface issues (glueing magnets etc) , as the mic just has to be touching the body.

 

[k7elp60]

Here is the schematic, 3 digit counter.

 

[Overclocked]

How about picking up the sound of the gun firing?

I guess the sound is quite specific, and this method reduces any interface issues (glueing magnets etc) , as the mic just has to be touching the body.

But what about noise from handling? I guess I could Connect the Mic to a PC, and analyze the spectrum when it fires. Isolate that range of frequency and build a filter accordingly.

Seems like a complex solution to a simple problem. I think the Hall Sensor Idea Should work Fine. Im also ordering SMD Parts and Through hole, since Ive never used Hall Sensors Before So I can experiment.

ADD: After studying the gun more closely, I tried to fit a 9V in the butt of a gun and it wont. However, The Gun has A LOT of space thats not being used by me (like near the trigger or on the opposite side of my arm pit). So I have 2 choices for batteries, a 9V or 4 AA Batteries. D and C cell batteries are way to humongous for this type of thing so that leaves AA or AAA or a 9V. AAA's have too little current, So that leaves 9V or 6V. Im using CMOS parts So It really doesnt matter. I guess in the long run a 9V will be easier to change than 4AA batteries.

Oh and everything is going to be attached via Velcro or something thats removable in case it needs repairs or something.

 

[Hero999]

Actually, AAA cells can provide more current than a 9V battery.

 

[Overclocked]

Seems Someone else did the same thing but for airsoft.
**broken link removed**

Now Im a bit curious, Ive taken my pistol apart before (and FYI, about 50% Is plastic), But Im curious to see how much space is inside of this thing. The Stock of the gun feels Unused, Wonder how the other places will be.

 

[Overclocked]

Just wanted to update, I found a source for Really Cheap (Free shipping!) Magnets. Observe and be amazed:
**broken link removed**
**broken link removed**

 

[Omar.M]

Not sure if this is valid, but why not keep it simple? Have a reset button, the little LED display, and a trigger switch.
When you press, have it subtract one from the initial value (since your gun can only take 12 pellets, just have an initial value of 12). And do so until 0. Then reset (reload at the same time) and ready to go.

-Omar