Mechanical watch timer - piezo disk to 'listen' and time?

Hi, I'm very rust with arduino and micro controllers but did a good few projects a few years back including making a coin change machine and a few other bits (http://youtu.be/luQkvtpEk6s)

I repair watches and make clocks and I've always wanted a timing machine. These are available reasonably from China, they are a very very basically a pickup microphone, listen to the tick tock and time it.

Would this be possible with an arduino? Most watches beat at between 4-8 beats per minute. We are describing a beat as a tick or then a tock.

The first job would be just listening and capturing the average beat time. The second job would then be allowing you to select the KNOWN beat from a menu and it displaying the error + or - from what it should be, a much easier value to work with as you can then adjust the watch to try and correct the error.

Any help appreciate. For the £150 for a timer of eBay, do I scrap the idea? Or, it would be a really useful tool for a clock and watch repairer so is it worth putting the time in and making this, which I'm willing to do providing I'm not going down an impossible or very difficult path.

Help appreciated.

Chris

An (adjustable) knock sensor may be useful for listening to the ticks. Dunno how complicated it will be otherwise to detect the ticks.

I also don't know how precise and stable the Arduino clock generator is. Some calibration may be required.

DrDiettrich: I also don't know how precise and stable the Arduino clock generator is. Some calibration may be required.

It's not usable for something like this. The resonator has an approximate frequency that has a severe sensitivity to temperature.

But with a DS3231 RTC, this project is very feasible.

I haven't seen the timing machines, but there's some chance the RTC might even out perform them.

craynerd: Most watches beat at between 4-8 beats per minute. We are describing a beat as a tick or then a tock.

Ummm, nope! :astonished:

It would be very cheap for you to just begin trying things. You can get contact microphones on Ebay for a few dollars. A preamplifier will probably be necessary, but I'm sure you can find that too. There are example sketches in the IDE for reading analog values, try running one that is connected to a mike on a watch. All that is really not a huge effort. After that, it's just a matter of fine tuning things.

Paul__B: Ummm, nope! :astonished:

I presume that was to my error of 4-6 beats per second.... Instead of minutes

Yep.

Hey friends, I need your help for designing a project using arduino uno and usb shield. I want to monitor the operating time of an electrical device like TV , And save results to show on computer. I'm not specialized in this field but i search and get information but i still can't perfom my project and it's very important for me . I'll be very thankful for your help.

craynerd: I presume that was to my error of 4-6 beats per second.... Instead of minutes

That makes much more sense as many mechanical wristwatches do 5 ticks/second.

I think in a German AVR forum I saw a description of such a project.

The sensor used was a piezo element, and the creator developed a microphone amplifier using an op-amp for amplifying and some extra components for band-pass filtering and threshold value detection.

As he states, the crown of a mechanical wristwatch has to be placed against the piezo element, and after some one or two minutes or so you will see the wristwatch deviation accurate up to 0.1s/day on the LCD display. In German he names his thingy "Zeitwaage", but I don't know the English translation. perhaps "timegrapher"?

Hi, I'm trying to make a watch timer and the first step is to at least get some sort of vibration input and recognise it. I've built the following circuit but it isn't even sensitive enough to pick up very light vibrations, it isn't bad but no way will detect a watch ticking...

Any suggestions to get this more sensitive? Video below...

http://youtu.be/16c9nzP2K1A

http://www.youtube.com/watch?v=16c9nzP2K1A

"This video is private"

You may have more success with an electret microphone and amplifier.

Weedpharma

Could you get better sensitivity if you clamp the piezo disk by it’s edge only and place the watch in the centre of the piezo. You may also do better if you had a resonance chamber on the back of the piezo.

All microphones require a preamp. Piezo mics are not very common and I assume that's because they are not good at picking-up sound (vibrations in the air) as they are at picking-up mechanical vibrations.

You could try modifying a stethoscope but adding a microphone. (And if it was me, I'd use a "normal" microphone such as an electret condenser or dynamic.)

I have yet to see a watch timer that doesn't use a piezo. Just one example....

|500x230

Well I switched out the piezo just in case and I have used the serial monitor but no difference, the sensitivity is no where there...in fact, I can just about touch the piezo and not trigger it, so I`ve no hope yet.

I guess I do need to work on the opt-amp, clearly the signal is not amplifying enough.

I really am quite poor with electronics, Ill be a little better once I have the circuit up and running. Can anyone advice on a better amplification circuit...Ill need quite a bit of guidance!

I look forward to your replies.

http://www.youtube.com/watch?v=16c9nzP2K1A

Well Ive had a go at cobbling together a piezo sensor and amp but Im just not getting any where near the sensitivity I need. I can actually just about touch the piezo directly and not get a detection. I`ve also edited the code since the video removing the LED and moving to a serial print but there is nothing hidden - it does lack sensitivity.

I have posted on the electronics sub forum for help with the piezo but hopefully now people can see I am going through with making this, I may get further discussion regarding the RTC (which I`ve now ordered) and the rest of the project. Any more suggestions or discussion about any of the timer would be welcome.

Ahmed930521: I need your help for designing a project using arduino uno and usb shield. I want to monitor the operating time of an electrical device like TV ,

Sorry, friend, you have posted in the wrong place!

Elektuur (now Elektor) electronics magazine published a project like this in January 1990 (in Dutch).
An improved version of an other one from Jan 1984.
They just put the watch flat on a piezo disc. The disk was glued to the top of a plastic case.
An preamp with ~180x gain and some frequency limiting was used before it went to a comparator.
Can’t post the diagram for obvious reasons.
But here are the pictures from the article.
Leo…

Watch_1.png

craynerd: http://www.youtube.com/watch?v=16c9nzP2K1A

Well Ive had a go at cobbling together a piezo sensor and amp but Im just not getting any where near the sensitivity I need. I can actually just about touch the piezo directly and not get a detection. I`ve also edited the code since the video removing the LED and moving to a serial print but there is nothing hidden - it does lack sensitivity.

I have posted on the electronics sub forum for help with the piezo but hopefully now people can see I am going through with making this, I may get further discussion regarding the RTC (which I`ve now ordered) and the rest of the project. Any more suggestions or discussion about any of the timer would be welcome.

Which RTC did you order?