23 Sep
2006
23 Sep
'06
2:28 p.m.
Hi
A friend has an older Celestron telescope with an AC clock drive.
We took one of those 12v to AC converters and added a couple pots
and switches to vary the frequency for tracking the telescope while
doing photo work. The converter used simple 555 circuits to control
the frequency so it was relatively easy to modify.
As a somewhat-related aside, IIRC there's a circuit in at least one
edition of tAoE to produce a not-quite-60Hz sine wave at 115V. Used to
drive a synchronous clock motor and get it to display sideral (rather
than mean solar) time.
-tony