The Bob's Biz Boys Ball Broker

by Bill Mills

Originally published in the December 1995 Action Pursuit Games


Parts Needed:

  • 1 Radio Shack Walk & Jog Mate (Catalog #63-682)
  • 1 compact momentary switch (such as Radio Shack #275-016)
  • 2 lengths of 18 guage wire - length depends on switch and counter placement.
  • Self adhesive velcro, epoxy, or some other method to mount the switch and counter.
  • Rosin core solder.

Required tools:

  • Soldering iron
  • Wire cutter/stripper
  • Jewler's screwdriver

Click on the images to see larger versions

Ever since the advent of paintball hoppers, I've thought about building a digital ball counter for my paintgun. It seemed like a good idea to keep track of how many shots had been fired since re-filling my CA tank, so I wouldn't get stuck with an empty tank on the field; and besides, it would look cool. It sounded like a simple project to undertake. Track down a digital counter schematic, round up the parts, build it, and hook it to a switch that is tripped by the hammer or the trigger.

Of course it was always a low priority project, and for one reason or another, I never got around to it, until now.

I stopped in to my local Radio Shack to pick up some much needed do-dad when I noticed a compact pedometer sitting in the display case. Priced at only $15.99, I spirited it away to its Pedometer internals new life on my paintgun. The Walk & Jog Mate (Catalog Number 63-682) is a nifty little yellow gadget that you can clip onto your belt. This marvel of modern technology counts your footsteps, and displays either the number of steps you have taken, or distance you have traveled (based on the length of your stride). It operates on a watch battery which is supposed to be good for 10,000 steps a day over one year. I figure that if I can afford to shoot 10,000 paintballs a day for a year, I could spring for a new battery (will my dream of becoming a professional recreational paintball player ever come true?). Since it already counted footsteps (actually it counts the number of times it is bounced up and down on your hip) I figured it shouldn't be too hard to get it to count paintballs. I was right. Converting the Walk & Jog Mate took less than an hour, and was much easier than building a counter from scratch.

This project is rather simple. It requires only very basic soldering skills, and it can be mounted on a paintgun with little or no modification to the 'gun. Please keep in mind that any modifications to a paintgun should only be made by an experienced airsmith (don't go drilling mounting holes in your paintgun unless you really know what you're doing!). Compressed gasses can be hazardous.

To start with, I opened the pedometer. Removing the battery cover revealed the two tiny Phillips screws that hold the packaging together. Out they came, and the back came off. Once the back was off, I could see how this little gizmo worked. Pedometer internals There was a pendulum switch that closed a circuit when jostled. The pendulum is the hammer shaped bar which pivots on the left side. Getting the pedometer to count something else is as simple as replacing the pendulum switch with a switch of another type. I removed the pendulum, its spring, and the small silver bar that the spring connected to (this was held to the circuit board by a single screw).

I soldered a wire onto the spot on the circuit board where the silver bar screwed in, and another to the gold plate where the pendulum end made contact. Connecting these wires (via a switch) closes the circuit and increments the counter. Pedometer internals With my ever handy Swiss Army knife, I cut a notch in the right hand side of the case back. This notch is basically a hole for the wires to come out, and could go just about anywhere on the back. I removed the flip-down front cover (this is the part with the belt clip) as I figured I'd never be closing the shot counter when it was on my 'gun. Guiding the wires through the notch in the back half of the case, I put the pedometer back together, and replaced the battery cover. The switch, and where to put it: I happened to have an appropriate switch lying about in a box of salvaged goodies (which is also where I put the pendulum - never know when I might need it). The switch should be a normally open, momentary, single pole single throw type (SPST, momentary in tech-speak). Double pole and or double throw switches will also work, but they must be of the momentary type. This means that they make an electrical connection when the button is pushed in, and break the connection when the button is released. The Radio Shack model 275-016 SPDT momentary lever switch is an excellent candidate.

I mounted my switch behind the trigger on my Stingray. Why there? Because it was just the right size to nestle in there easily with out any cutting, drilling, or gluing. The switch could also Ball counter mounted on Stingray be mounted up on the side of the receiver, where the cocking knob could press it each time the bolt cycles, or even inside the hand-grip where the trigger mechanism could activate it. I prefer the idea of mounting the switch behind the trigger, as it is less likely to interfere with the blow-back of the hammer.

Hooking the switch up to the circuit was simply a matter of soldering one of the wires from the pedometer to each of the terminals on the switch. A bit of black spray paint to subdue the yellow case, and self adhesive Velcro patch later, it was mounted on my 'gun. The Radio Shack pedometer was now a "Bob's Biz Boys Ball Broker". The pedometer has two modes, distance and steps. I've switched mine to step mode, and simply covered the switch with electrical tape since I will not be moving it back.

I've found that this counter isn't perfect. It has trouble keeping up past 4 shots per second, so as long as I don't go into spray-n-pray mode too often (sometimes my trigger finger gets a mind of its own) I find I've got a decent handle on how much paint I've shot, and when it's time to refill my tank. Plus it looks cool.


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