DIY - sort of - using PC as an oscilloscope

[Davidm]

I'm looking for a program that will let me use my PC as a crude oscilloscope, to help me setting the beat of a pendulum wall clock. The idea is to connect a microphone, positioned near or in the clock and display a waveform of the sound of the beat, so that I can adjust the movement to get an even beat (tick tock).

So the program would need to display the waveform of the sound received, have some sort of amplitude trigger to display a syncd display, plus maybe an adjustable low pass filter just to remove some high frequency noise to help with the triggering.

Anyone got any ideas? (PC is Windows 7)

[Lee]

First hit in Google gives this:

[Davidm]

Cor - that looks brill, thanks!

[Bob Minchin]

My feeling would be that the combination of the sampling rate of the ADC and software latency is not likely to give the degree of accuracy needed for clock setting.

[John Williamson]

+1

A useful program.

Alternatively, Audacity has a live waveform display available.

[Martin Brown]

The clock need not have an even beat to work. The crucial thing is that you get one tick per second (or however long it is meant to be).

Most of them will identify frequencies pretty well for pure tones. But they are not optimised for very low frequencies like a pendulum clock.

Daqarta (sp?) is one of my favourites as it will do realtime FFT vs time display of the input signal which is great for science demos.

[Brian Gaff]

Is this not a bit of overkill?, I'd have thought you could hear if it sounds right. More importantly, is to make sure the clock keeps good Time I'd have thought. Brian

[Kevin]

If a pendulum clock is in reasonable condition, it should run even if it is so out of beat it's painful to the ears.

If you really can't do it by listening, then stick a post-it to the case back, just behind the rating nut below the pendulum. Stop the clock, and mark the post-it with the position of the tip of the rating screw thread. Hold the pendulum gently and move it slowly sideways until you hear a tick. Mark again. Still holding gently and moving slowly, move it in the opposite direction till you hear the tock. Mark again.

The marks should be equidistant from the centre position. If not, adjust. And that can be the hard bit - longcase (grandfather clocks) require you to bend the crutch stem - a bit of iron wire which may have been replaced with anything from a strand of .036 copper to some high tensile fence wire. Most wall clocks incorporate a crude slipping clutch arrangement to secure the escapement to its arbor, and it's easy to move it too far. So-called Vienna Regulators are the easiest - they have a fine screw adjuster at the bottom of the crutch.

If you want to hear the effect of an out-of-beat clock, tilt it and listen. Many people tilt it till it sounds right, mark the wall, and put up with the appearance. Or count the coins they've used under one side of a mantle clock.

But you don't need a PC.

Kevin

[Scott M]

The Mk I ear is jolly good for that, I find. It's easy to detect when they're limping.

[Davidm]

Well the PC scope thing didn't work, either the mic wasn't sensitive enough or the response of the program couldn't cope.

I could hear the off beat, but not well enough to get it as even as I wanted. Ended up using the pendulum swing measurement method and eventually got it swinging evenly each side, and it sounds ok to my, slightly deaf, ears.

The crutch did indeed have a clutch arrangement onto the armature, so didn't have to bend anything.

Hopefully when I get it back in the case we can now have the case vertical, rather than somewhat obviously tilted to one side. SHMBO will be pleased!

[rick]

Did seem that Long case clocks been built for a very long time without need of a scope ... As another poser said .. surely what is more key is to adjust until it keeps the right time.