Timegrapher Project

[NoraE]

Like everyone else in the hobby / profession I felt I needed a timegrapher though even the cheep ones were out of reach. So I tried to find something for a phone app and came across this as a free pc down load.
About Watch-O-Scope - Watch Timing System It requires an OP amp to work, but also gave plans to make it, the PC board, and a mic stand. I thought since I know how to solder and can read a schematic I'd give it a try. It's my first from scratch project and am happy that it turned out. I went with a breadboard because I didn't feel the desire to learn to etch anything at this time. It's obviously not finished but it works. I have no idea what the graph represents so I'll just have to learn.

 

[Dr. Jon]

NIce. If you have a phone or an ipod touch with a four way input all really need is a microphone. The audio amps in these devices are a lot better than anything anyne but a very professional audio engineer is likely to build. I am not disparaging amateur electronics, but, pointing out the phone makers spent a lot of time and money on these designs.

The graph output is telling you several things:

The vertical separation between successive "hits"is the measure of how close the watch is to being in beat, The AP figured this out and posted it. The jumps are due to the line moving and the system resetting. It curvature tells that teh watch rate is varying usually because it needs new lubrication. A well set up watch will lay down a straight trace.

The Witsci site ,

Instruction document, you can download instructional material on what the traces mean.

 

[NoraE]

it needs new lubrication

It does need a service.

 

[Chris Radek]

That's awesome! The jumps look like galloping (too high amplitude). Does the watch gain a lot?

If so this is fixed at the next service with a weaker mainspring.

 

[Dr. Jon]

No the jumps are not overbanking. When that happens the traces get completely disorganized and it takes several seconds for a clean(readable) trace to develop again. The software is processng the delays modulo a fixed time and resetting.

All of the various pathologies are described in the Witschi publications that are available from the site.

The one time I did see my wat ch overbanking, the reason was that the clutch on the mainspring had stuck. It was winding too hard, which showed up after wearing the watch on a long run.

 

[DeweyC]

Like everyone else in the hobby / profession I felt I needed a timegrapher though even the cheep ones were out of reach. So I tried to find something for a phone app and came across this as a free pc down load.
About Watch-O-Scope - Watch Timing System It requires an OP amp to work, but also gave plans to make it, the PC board, and a mic stand. I thought since I know how to solder and can read a schematic I'd give it a try. It's my first from scratch project and am happy that it turned out. I went with a breadboard because I didn't feel the desire to learn to etch anything at this time. It's obviously not finished but it works. I have no idea what the graph represents so I'll just have to learn.

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Nora,

This seems to have all the functions of my Microset at 1/20th the cost. Nice find. I looked at what he uses for the timebase, and the soundcard may work although it would be terrific if he pulled the time calibration directly off NIST. All those fuunctions help with diagnostics.

Also, it appears like there is a setting to trigger for the signal to be used for amplitude. There are some watches that are very quiet and difficult to measure amplitude.

When I do long term timing tests for chronometers, I check at the same time every 24 hours. Before the test I do an update to my computer clock as provided by NIST using NetTime. I found that in those 24 hours my computer clock can drift up to 2 seconds.

But, unlike my Microset, the system you found can be calibrated before each use. And to be honest, I take my readings from the MU-700 with blind faith (been told by Dale Sutton they either work right or not at all).