> 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.
True -- it's a common technique in synthesizers. > 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. The LPro-101 manual offers some advice of uneven quality on that subject, but I think you'd be fine with either a two-transistor differential amp (http://www.wenzel.com/documents/waveform.html) or a 74AC-series gate (http://www.ke5fx.com/ac.htm). See the other thread on reference-oscillator input circuits as well. -- john, KE5FX _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
