[sdiy] Give me an 'A' !!

[Gene Stopp]

3-transistor sinewave oscillator (not sure of the topology, wein-bridge
maybe?) with tuning trimpot, powered between +10 and ground. Tuning based
purely on component values. The "A-440" switch on the front panel applies
+10 to the circuit, so it's not powered up when it's not in use. Seems to
stay in tune pretty well, good enough for rock n roll.

I do have sitting in a parts drawer somewhere a little circuit board I made
a while back, with a crystal, some dividers, and buffered passive lowpass
that puts out 440.00000something hertz. Runs off of +5. I don't remember the
crystal frequency, but I seem to remember that I did some math and then
looked through the parts drawers in a lab at work and found something. My
advice would be to look at a catalog page with crystals on it, and do some
divide by 2's and 3's until you get a hit, then figure out the dividers
needed.

- Gene


-----Original Message-----
From: Tim Ressel [mailto:madhun2001 at yahoo.com]
Sent: Wednesday, October 16, 2002 7:55 AM
To: Synth-DIY list
Subject: [sdiy] Give me an 'A' !!


To all,

I seem to recall the old Moogs had a built-in
calibrator which produced A-440. How was this done?
Was it accurate? Is there a crystal that will divide
down to 440hz?

--Tim Ressel


__________________________________________________
Do you Yahoo!?
Faith Hill - Exclusive Performances, Videos & More
http://faith.yahoo.com