EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: blewisjr on September 16, 2013, 12:52:31 pm
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Hello Everyone,
It has been a while particularly because I wanted to do another project but I really wanted to make sure it was something I could use.
There are products out like this that are very advanced but I am looking to do something simple and there is nothing like using your own project for something you enjoy doing.
I am big into pistol shooting as another hobby. It is really a lot of fun. There are devices out there you can purchase to actually time your shooting.
The device works like a sound triggered stop watch. You set the device and after a certain amount of time it beeps. At this beep is when the time starts when you fire the sound from the gun discharging enters a microphone and stops the stop watch and you now have the time it took say to draw, acquire your target, and then fire.
I want to build a simplistic version of this device that I can improve over time.
I already know I am going to use a ATtiny2313A to handle all of the processing and display updating etc...., I also know I need a microphone hooked up to the device.
Now I figure I can hook the microphone into the analog comparator of the ATtiny2313A and use the voltage spike of the microphone to trigger off a certain threshold through the comparator interrupt.
The issues I see is voice stopping the clock or other pistol shooters at the range prematurely stopping the clock. Anyone have any thoughts on how one could prevent these issues in the design?
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Are you shooting from a fixed position or do you move around? If you stay in one place, I think it'd be better to go with an optical bullet detector since it won't set off from someone firing/shouting next to you. You'll need an infrared LED and a photoresistor/transistor/diode to see when the bullet passes through.
What are your plans for the beeping? A shooting range would be a rather noisy place and you will probably be wearing ear protection.
Also, you could log the results in the EEPROM and view them later at home.
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Typically it would not be a fixed position so it needs to be portable and be able to fit in say a little open pouch.
As for the beep it would just be a buzzer. With the right resistor value the piezo can easily be heard even with proper hearing protection. Hearing protection does not make you deaf it just protects you from the high decibel levels of the pistol or rifle. It would also be possible to store the results on a simple sdcard as well if the storage is done by say a separate chip. I can worry about storage later on in the project.
The IR method you suggest makes sense however it is not practical from a portable perspective. As I sated you should be able to set it, slide it in the pouch it beeps you fire and you can then check the timing and possibly store it to memory in some fashion be it EEPROM or some other method for later viewing. So it really seems as if the microphone is the only way.
If I understand correctly the farther away a individual is from the weapon the lower the decibel level would be due to dispersion over distance so maybe there would be a way to filter it at a certain trigger point?