Optimization of Timegrapher data

[Lancaster]

I've been using a basic Weishi 1000 timegrapher for a few years now and it's been informative helpful. But not as informative (or at least accurately so) as I thought. Only recently have I found that there are ways to get improved readings that I didn't know about. Turns out it has a gain control, and increasing that has given better readings. Or does it? Particularly in the trace there are fewer random dots with cleaner, more uniform lines now. I assume that the higher gain is giving the more accurate reading? Any thoughts?

Also, the sliding spring loaded side of the clamp has a notch which prompts you to lay the watch with the crown side against that, inserting the crown into that notch. But it turns out that this is wrong. The microphone is at the other, fixed end of the clamp, and so the watch should be laid in (face up) with the crown at that end. I've only tested one watch since I've discovered this and, while the numbers didn't change significantly the trace certainly did. It appears to be a much healthier watch than I thought!

I've had that fixed end covered with a couple layers of scotch tape. Perhaps that shouldn't be done either.

 

[ExpiredWatchdog]

The gain works both ways. Some watches have trouble tripping the timer consistently and need a higher gain setting. On the other side, if the gain is too high, ambient noise will trip the timer randomly and cause inconstant readings (off-curve dots).

As far as scotch tape, I highly recommend it taped to the case where it contacts the microphone, just a single layer and only to protect the case from scratches. While some recommend placing the crown against the fixed end but I've never had to; it usually goes thru the cutout.

I have a 1900 so I can't speak to the 1000's capabilities, but the 1900 has a few help pages that explain some features (written in Chinglish, of course). The two I pay attention to are the resolution (999 seconds or 99.9 seconds) and the sample time. The higher resolution shows accuracy down to 1/10 sec and the sample time says how many seconds of data are used to average the time. Of course, the lift angle goes without saying.

 

[Lancaster]

Good to know. I'm testing in a very quiet area so ambient noise isn't a problem. Setting the gain high eliminates the few random trace dots that show with a reduced gain on this particular watch, and tightens up the 2 lines. I don't believe the resolution can be changed on the 1000. Are you saying that instead of the timing reading, for example, +6 sec you can get a reading of perhaps +6.3 secs? The sample time is adjustable which I've set at 12.

Why do you recommend putting the tape on the watch instead of on the timegrapher? Seems like having it on the TG would be a one and done deal, and avoid possibly having to clean adhesive residue off the watch.

 

[Lancaster]

I've also found that the ambient room temperature greatly affects the results.I'd been taking readings in the basement where it's 10 degrees cooler than a floor above. When I took readings there the beat error improved from 260 to 290 or higher, and the rate went from +3 to 0. Beat error went from .03 to .02.

On one watch I noticed that loosening the screw down crown a bit gave much better readings. It could've been the particular watch, but it was giving a terrible trace and numbers prior to doing that. Wouldn't have known this was an issue without the timegrapher.