This is an electronic starter pistol for track events that everyone will be sure to hear!
What’s a starter pistol? A starting pistol or starter pistol is a blank handgun that’s fired to start track and field races, as well as competitive swimming races at some meets. The sound of the gun going off serves as the signal for the athletes to begin the event.
Electronic Starting Pistol – A Quick History
The starting pistol, first used in the 1904 Olympics, is still in use today.
Initially, starting pistols have taken the shape of revolvers and fire specially designed blanks that release a plume of smoke to visually signify the start of the race. In fact, the starter pistol is designed to release a little cloud of smoke so that officials at the finish line begin the clock according to when they see the gun fired rather than when they hear it.
Later, these traditional guns have been attached to electronic starting systems which projects a beam of light across the finish line that, when broken by an athlete, triggers the time keeping device.
In the wake of increased security concerns, and to clear some issues with triggering races with a literal bang, from the Summer Olympics of 2012, electronic starting pistols became the standard way to start a race. When its trigger is pulled, the electronic starter pistol (starting gun) does three things simultaneously – a light flashes, a pulse is sent to the electronic starting device, and a recording of a gunshot plays.
See also https://en.wikipedia.org/wiki/Starting_pistol
Electronic Staring Pistol – Make It Yourself
This is the photograph of the JEX700-2 Electronic Starting Pistol from Jex Sports (http://www.jex-sports.com/Product-2009612134731.html). This multifunction gun has two 3.5mm output ports, one for sound, the other for connecting timing equipment.
An electronic starting pistol is not very expensive, but if you are on a tight budget, or like do-it-yourself projects, you can build it yourself for a small cost. It will also be more flexible than commercial electronic starting pistols since you can decide what type of sound you want and how to trigger the start. I will go through the necessary components and steps.
The proposed concept is very simple, ie, make a battery-powered electronic tone maker and finally pack the entire assembly inside an empty toy gun enclosure. Below is the blueprint of the do-it-yourself electronic starting pistol.
There’re numerous ways to build an electronic tone/noise maker with or without using microcontrollers. Currently, my pick is a cheap COB (chip on board) module – the CK9561. Note that some online sellers sell this small COB module under the name KD9561. This appears to be a module used in kids toys and is normally considered to make four different tones depending on the connection of two of the pads SEL1 and SEL2.
The CK9561 module is the latest in a series of music effects COBs I’ve been testing. This COB module requires just a few external components to operate:
- A resistor to control the speed of the sound effect (oscillation frequency)
- A small signal transistor to drive the loudspeaker
- A selector switch to set the sound effects according to the following table
|PAD SEL1 (K1)||PAD SEL2 (K2)||SOUND EFFECT|
|X (don’t care)||HIGH||MACHINE GUN|
This is all you would need to do to build a tone maker as simple circuit ideas can be found on the internet utilizing very few external components to produce the required sound effect. But the next crucial thing in this case is to tailor the setup to work as an electronic starting gun, which obviously needs the following basic schematic.
This simplistic schematic does not require an in-depth explanation, but here are a few things that need your keen attention.
Note the value of the resistor R1 in the schematic employed to set the “speed” of the sound effect. The recommended value is in the 100K to 390K range – higher resistance slows the speed of the effect down. A fixed 100K resistor in series with a 220K trimpot might be a good configuration for experiments.
Also notice that the piezo speaker (PZS1) which’s actually a magnetic transducer which has a 16Ω coil resistance. Below you will find an excerpt from its datasheet published by KINGSTATE.
I made a crude breadboard prototype at first to do some experiments.
To make breadboarding easier, I attached a male-header strip for testing the COB module on the breadboard. Here’s how the physical connections are made, and what the COB module looks like with the header strip.
I only used the required connection points, so there are some gaps in the soldered male-header strip!
The breadboard assembly is powered by a 3V battery (1.5V AAA x2) during testing.
Look, the value of resistor R1 in my breadboard prototype is 270KΩ.
Finally, as you might already noticed, the default output in my setup is the “machine gun” sound effect. You can easily change it by toggling the High/Low states of the pads K1 and K2 thru a 3-way slide switch (not shown in the above schematic).
When considering further modifications, you can change the wiring of LED1 as indicated below so that the red light can deliver flashes in a rhythmic style rather than a steady glow.
Only one thing remains, as far as the construction is concerned, is the enclosure. Since there’s not much internal wiring and circuitry, a cheap toy gun can be used the enclosure. Fortunately, this idea is not difficult to implement – I leave it to you 😜
So now you’ve a working starting pistol with 4 sound effects. The bright red lamp helps timekeepers to start their devices accordingly.
Commercial models usually rely entirely on external audio amplifiers since a strong start sound in a noisy stadium is an absolute necessity. Still, a small built-in speaker makes a nice standalone device that can be used for regular practice sessions.
So, like with all commercial electronic starting pistols, you need to connect the AUX output (3.5mm stereo socket) of the pistol to a powered speaker or a public address (PA) system with LINE IN/AUX input to amplify the start sound.
You can also connect your starting pistol to a timing device/race clock to the AUX port of the timing device with a stereo cable to split the output signal (see below). The main advantage of a direct connection rather than using a microphone placed close to the starting pistol is that it is completely insensitive to external noise since it looks for an electronic signal, not the sound.
With clever hardware additions you can connect this starting pistol directly to Android and Apple phones to work with fantastic race clock/timer apps. There’re also several other odd ideas, and I’ll try to share them in a later post. I have tested a couple of them and they worked as expected!
SPOILER: The CK9561 COB module I used in this project is in fact a part of the quite popular Chinese “16 Music Box DIY Kit” (https://www.arduino-tech.com/5pcs-diy-16-music-box-16 -sound-box-kit-electronic-diy-suite/) I bought in an online auction only cost nearly the same as the sound effect generator module itself!