Sound (gunshot) triggered light Project

[mistertim887]

Hi.
I own and work at a shooting range in the UK.
It would be great if anyone could help or advise me with my latest project.
I would like to create something that triggers an instant, red flash next to a 100 yard target whenever a shot is fired. It is important that the flash is red, bright and instant. The flash needs to be nearby to the target, whilst the microphone needs to be in the shooting bay. I did some research and purchased this ‘sound to light’ product from maplin: http://www.maplin.co.uk/sound-to-light-led-22545 Would it be possible to remove the LED’s that come on this product and replace them with something like this, on a 100 yard wire?: http://www.rapidonline.com/electron...per-bright-red-led-dot-matrix-display-57-0655
Also, it would be very important that the microphone only triggered a red flash when a shot is fired, not during laughing or conversations in the shooting bay etc. (maybe need to modify or replace microphone or circuit component e.g. potentiometer to decrease mic sensitivity???)
Finally, although not essential, it would be much better if the flash worked wirelessly, (i.e. no 100 yard wire required between the maplin ‘sound to light’ product/(microphone) and the led matrix (red flash) 100 yards away by the target. However, this needs to be a very cheap DIY project and trying to create wireless communication between the devices might escalate the cost greatly. However, for this, I did think about buying a pair of cheap ‘walkie talkie’ radios that have LED’s which illuminate when the other person calls you, removing the un-needed components, and somehow attaching one to the modified maplin ‘sound to light’ product and the other to the superbright red led matrix.
Any help or advice would be much appreciated.
Thanks
Tim

 

[Sam Gangee]

I don't see a circuit diagram for the Maplin unit so it's impossible to be certain. However, it looks as if it will do the job of sensing the report from the gun and it appears to incorporate a sensitivity control. However, there's no simple way to distinguish between a gun, dog bark or laugh, other than peak volume level. Consequently, the microphone would need to be close to the gun.

You then have the problem of taking the electrical pulse from the point where the LEDs are connected and feeding it to a suitable (legal) transmitter.

Plus the challenge of designing and adding a circuit to the receiver to change the incoming signal to a flash of light. This would probably need to be a xenon discharge tube in order to be seen at a distance from a wide angle in daylight. (Blink and you've missed it.) The LED display from Rapid wouldn't be visible.

Unless you have a good understanding of electronics and practical experience, you won't be able to do this. There's probably a designer somewhere who would have the time and interest to do it but it wouldn't be cheap. In addition, unless your specification is carefully written, you could end up with something that doesn't do exactly what you expect.

 

[ericmark]

I am trying to work out what the flash is for? Although light and electricity travel faster than a bullet by time it works the flash it could end up before or after the bullet hits the target. Clearly nothing is really instant. Just look how slow a PC is.

Understanding why may help in working out how.

From the target position could the detector hear the sound or see the flash from the gun? Why would the detector be in the shooting bay?

 

[mistertim887]

Hi Sam

Thanks for your quick reply!
Since posting and ordering the Maplin unit I've done a bit more surfing around the web and found the 'SK2 Flash trigger unit' here http://www.hiviz.com/kits/instructions/sk2-manual2.htm.
I'm thinking of ordering the parts for it.
It's designed for high speed photography (Balloon Bursting Photos etc.)
In action: http://www.youtube.com/watch?v=XGCFG47x6O4
Build Instructions: http://www.youtube.com/watch?v=iuNRUyI52FY
I think it may be a bit easier to manipulate than the maplin unit for my needs.
Do you think I could substitute the potentiometer for a less sensitive potentiometer (rather than the "click sensitive" one used in the instruction video) to make sure it only reacts to gunshots and attach the piezoelectric element to two pieces of 100 yard hookup wire??? Then cover the flash unit with a thin film of red cellophane to make the flash red?

I don't see a circuit diagram for the Maplin unit so it's impossible to be certain. However, it looks as if it will do the job of sensing the report from the gun and it appears to incorporate a sensitivity control. However, there's no simple way to distinguish between a gun, dog bark or laugh, other than peak volume level. Consequently, the microphone would need to be close to the gun.

You then have the problem of taking the electrical pulse from the point where the LEDs are connected and feeding it to a suitable (legal) transmitter.

Plus the challenge of designing and adding a circuit to the receiver to change the incoming signal to a flash of light. This would probably need to be a xenon discharge tube in order to be seen at a distance from a wide angle in daylight. (Blink and you've missed it.) The LED display from Rapid wouldn't be visible.

Unless you have a good understanding of electronics and practical experience, you won't be able to do this. There's probably a designer somewhere who would have the time and interest to do it but it wouldn't be cheap. In addition, unless your specification is carefully written, you could end up with something that doesn't do exactly what you expect.

 

[Sam Gangee]

Please don't "quote" posts like that. It serves no useful purpose and, if I made a mistake, I can't correct it in your copy.

A piezoelectric transducer is a high impedance device and should be connected by very short wires to minimise the risk of interference.

There's no such thing as a "less sensitive potentiometer". Your questions lead me to believe that you need to learn about electronics before you tackle this.
http://www.The-Cool-Book-shop.co.uk/begin.htm

 

[mistertim887]

"Quote Posts" serve a very useful purpose; you get an email notification upon each new reply, and, Personally, I tend to log into my email account a lot more than this I log into forums. I suspect most other users do too.

Piezoelectric elements are high impedance components. However, from previous projects using them, I have determined that the combined effects of shielded hookup wire, plastic encasing, and adding a silicone based sealant or caulk to the back of the ceramic transducer pretty much eliminates interference, regardless of wire length.

There are such things as Potentiometers of differing sensitivity. "Sensitivity" is effectively "ohms per volt". Potentiometers are variable resistors, and also variable voltage dividers. Pot sensitivity can be calculated by considering its potential gradient, put simply, its 'batteries volts/length of pot wire'. Therefore, to increase pot sensitivity you can change the length of it's wire, a longer pot wire will result in a more sensitive pot.

Read up on how Potentiometer's work: http://goforaplusplus.wordpress.com/2011/09/19/principle-of-a-potentiometer/

I'm afraid my question must have mislead you.
Thank You for trying to help.

Please don't "quote" posts like that. It serves no useful purpose and, if I made a mistake, I can't correct it in your copy.

A piezoelectric transducer is a high impedance device and should be connected by very short wires to minimise the risk of interference.

There's no such thing as a "less sensitive potentiometer". Your questions lead me to believe that you need to learn about electronics before you tackle this.
http://www.The-Cool-Book-shop.co.uk/begin.htm[/QUOTE]

 

[Sam Gangee]

Since you've quoted me again and you seem to know more about potentiometers than I do, despite my degree and 52 years in the business, I'm out.

 

[SimonH2]

"Quote Posts" serve a very useful purpose; you get an email notification upon each new reply

Doesn't make any difference whatsoever You only need to make sure the "Notify me when a reply is posted" box is ticked when you reply - you can change the default for this in your user settings. If the box is ticked then you'll automatically be notified of replies whether you include a quote or not.

General netiquette is :
If you are simply replying to a post then don't quote it at all - just add a reply.
If you are replying to a selected part (as in this case) or are replying to various bits, then quote only as much as is needed to make the context clear (and consider splitting up the quoted material)

I tend to log into my email account a lot more than this I log into forums.

Ditto.

Therefore, to increase pot sensitivity you can change the length of it's wire, a longer pot wire will result in a more sensitive pot.

The range of adjustment a pot gives you is determined by it's resistance value and how that relates to the circuit it's in. A pot could give you 0-100%, or 90-100%, or 0-5%, or anything else depending on the circuit it's in. From the context, I think this is what Sam thought you were referring to (as was I).

If you want sensitivity in adjustment (high resolution), then you need a high quality, preferably multi-turn, cermet pot rather than a wirewound. Wirewound pots tend to be fairly coarse (resolution is limited by the "steps" in the wire winding), while conductive plastic ones tend to be very fine (as do carbon track but they wear out and can be unstable). This has nothing to do with ohms per volt !