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More about special timing device

Thinking (I know, it's dangerous) this afternoon about my need for a special timing device led me to stop watches. If two stopwatches were wired together with three switches such that the first switch started started both stopwatches simultaneously and the other two switches stopped their own single stopwatch I would have what I want. But I can't, after spending some time online, find a pressure activated switch that will work. I am open to any suggestions. So far I have recieved much good advice on this project and want to say how much I appreciate the folks who have helped me so far. I am sure I will be able to eventually come up with a fairly inexpensive solution, but really the solution most likely will come from someone here and I'll just be the one implementing it. Thanks, Eric

Reply to
etpm
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This is that device where two hammers get out of synch?

Piezos (those that you'd talked about) would work fine coupled to a microcontroller if you can place them somewhere they won't get destroyed but will get "pinged" by the impact.

Here's a link to look at when thinking still more dangerously:

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A micro could easily set up the two timers you require, with something akin to that as sensors. Not sure how you start the timers, though. You don't say. If you had a PC nearby, that could replace bothering with a display, since USB can transmit the timing values to the PC via a virtual RS-232 port from almost any really cheap micro kit (plenty of suitable ones at $10, in one-each qty.)

Jon

Reply to
Jon Kirwan
[snip]

A contributor on Hackaday posted about a somewhat similar project; he used an audio editing package (Audacity) to measure the response of a DSLR shutter by recording the clicks, then using the timestamp feature to determine the interval between sound bursts.

One microphone, one pc, no damage.

I can't paste a link from this pc, but you can search Hackaday for the title:

"DSLR performance measured with audio editing software".

HTH

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Reply to
Randy Day

This was two hammers whacking pins into a panel or some such?

It just occurred to me that an accelerometer on the base will detect the impacts, but not distinguish between them. Accelerometers on each hammer should detect the individual impacts, if you can sort the wiring out. Just about anything between the hammer and the pin will get beaten up in short order...

Accelerometers aren't going to actuate the switches easily, though -- I'm going to reiterate my advice that if you charge by the hour you should just get an inexpensive oscilloscope. I'll bet you spent enough time looking for ideas by now that you could have bought at least one cheap scope, and maybe a couple of accelerometers with power supplies.

If you really need to go cheap on the accelerometers, use electret microphones. Buy lots -- I'll bet they don't last long in that service.

--
My liberal friends think I'm a conservative kook. 
My conservative friends think I'm a liberal kook. 
Why am I not happy that they have found common ground? 

Tim Wescott, Communications, Control, Circuits & Software 
http://www.wescottdesign.com
Reply to
Tim Wescott

Greetings Tim, You're correct, I have spent a bit of time on this project. But it will probably be worth it for one of two reasons. First, I get to learn how to do something I'm interested in, and second it may make me more valuable to the customer. Eric

Reply to
etpm

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