Recently I bought a Efratom Ru frequency standard from eBay and a
frequency divider chip that makes 1MHZ,100KHZ,25KHZ,10KHZ,100HZ and a
1HZ output. Today I thought of a way to make a nice 60HZ so you can use
a mains-powered clock for the display (using amplifier and transformer
wired "backwards"). But, now you'll need 60HZ. A European has it easy
with 50HZ as you use a BASIC Stamp or Arduino to divide the 100HZ
output. But for 60HZ I came up with a solution:
You set up the Arduino to take the 10KHZ from the divider chip and
program it to count off 83 pulses to flip an output. But wait! Unless
you add a "leap count" every 3 flips of the output, it'll run fast.
Assume at the start the Arduino output starts high then turns low:
(83+83+84+83+83+84)*20 = 10,000 pulses = one second
H__L__H__L__H__L
Every output cycle and a half the voltage swing is a little over 1
percent longer because of the leap count. This means that the distortion
adds a slight inaccuracy, not enough to upset New Year's revelers. But
if you want a better 60HZ, try using the 100KHZ:
(833+833+834+833+833+834)*20 = one second
You see where this is going with leap counts. The ultimate of course is
one really good Arduino and (after a hex inverter to amplify it) take
the straight 10MHZ and apply this leap count technique:
(83333+83333+83334+83333+83333+83334)*20 = one really accurately made
60HZ = one nice second, just the thing for a Nixie clock. :)
Now, what is a good hex inverter to take the 10 million HZ of my
rubidiom movement to feed a frequency divider chip (and later Arduino)?
It needs to take the .5 of a volt sinewave and squarewave it and in a
normal 14 pin DIP (breadboardable) package.
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