Tom Van Baak (mobile) wrote: > > But one easy way to do it today is start with a $5 standard > quartz clock display. 1) Either run a precise synthesized > 32 kHz signal into it (replacing the xtal), or drive the little > bipolar stepper yourself. > > A 50 millisecond +1.5 VDC pulse is all you need; next > second give it a -1.5 VDC pulse, etc. This is a few lines > of code for a microcontroller. I've got pictures of this > somewhere on my web site, I think. >
Tom, With all due respect to your love of software, a microcontroller is a bit of overkill for this application. Use a 74HC74 D flip-flop connected as a divide-by-two toggle register: connect Q-not to the D input and feed the 1PPS into the C input; connect S and R to +5V. The drive pulse to the coil is generated very simply with a capacitor (~0.1 uf?) in series with the clock solenoid. This will produce a positive pulse when the flip-flop flips and a negative pulse when it flops. You don't need to worry about the 1.5V coil voltage rating - the capacitor will absorb the blow. I'd start out with a smaller capacitor (.001uf maybe) and increase it until it pulses reliably, then select perhaps twice that capacitance for reliability. _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
