There was a question about what kind of accuracy would be required. Well, the more the better. Without electronic assistance this was done by letting the clock run for a day and measuring it against a known good time source, adjusting the pendulum, repeat. Running the clock for longer periods between measurements obviously makes the adjustment more accurate. With electronic assistance the same rules apply. Running the clock longer between measurements makes the adjustment more accurate. Let's do some math. Assuming we use one pendulum cycle to measure the period and say that this clock is geared for a one second pendulum cycle. If we can measure that one second with an accuracy of 100ths of a second, then our average error will be half that or 0.005 sec / sec or 0.3 sec / min or 0.3 min / hr or 7.2 min / day or 216 minutes over 30 days If this is a 31 day clock, over 3 hours off is not very good per winding. If I can get millisecond accuracy, then I'm down to 21.6 minutes over 30 days which is still not very good. Now if I increase my sample size to 10 pendulum cycles and still maintain millisecond accuracy, I can set the clock within 2.16 minutes lost/gained in 30 days. That would be a good start. It would only take me 10 seconds to decide to adjust the clock slower or faster and I would eventually be correct to within .072 minutes per day when I finished adjusting to the accuracy level of this instrument. Further adjustments using longer sample times would then be able to increase the accuracy to the desired level or at least to whatever level of accuracy the clock works are capable of. Returning to one of my original questions. Does anyone have any suggestions for useful libraries or example source code to study as a start for this project? ----- End forwarded message -----