In article
,
Joe wrote:

I actually built this thing circa 1980, and still use it. I recently
found pdf's of a manual and circuit diagram for it at

http://www.pestingers.net/Heathkit_m...sequential.htm

A quick look at these pdf's didn't tell me any specs for the speaker,
tho.

Joe-

Back in the 70s I built a kit clock using parts and instructions from
Radio Shack. The specified 8 Ohm speaker was driven through a 100 Ohm
series resistor. I found a small 100 Ohm speaker, and figured I might
get more power transfer if it matched the resistor. The result was
definitely louder than the original 8 Ohm speaker.

I didn't try it without the 100 Ohm series resistor, which would be
similar to your configuration. Suppose your square wave was 10 V RMS.
As an approximation, that would produce one watt into a 100 Ohm speaker,
which is probably louder than your neighbors would like!

I still have the old clock and have enhanced it over the years. It now
has a 9 volt battery backup with its 60 Hz signal coming from an
oscillator that divides down a color burst crystal tuned to 3.579540
MHz. The frequency may drift a bit, but it doesn't stop when the power
fails.

Fred