I’m thinking of building a power supply for breadboarding purposes. I want to take a signal tap from the 60Hz AC between the stepdown transformer and the bridge rectifier, and turn it into a TTL level clock signal. I want the clock pulse to be no more than about 10-15 milliseconds wide, but I would prefer it to be 1 ms or less, as long as it’s still within TTL specs. I intend to run that 60Hz clock through a divide-by-6 counter to get a 10Hz output, then a divide-by-10 to get a 1 second clock, too, so that I have three clock signals available: 60Hz, 10Hz, and 1Hz.
I haven’t decided what voltage I’m going to use for the transformer. I’m leaning toward something above 15v, so I can have regulated 15 & 12 volt outputs, as well as a 5v, but my primary use for the power supply is a Basic Stamp development board that uses a 9v battery, so 9v unregulated can power that, and still give me 5v regulated. I’ll take that, if that’s what will give me 9v for the board, plus the clocks for whatever I’m designing*****. The higher regulated voltages are optional. The clock signals aren’t.
Ideas on actual circuits, or links to webpages that describe how to turn AC into narrow TTL level DC pulses are welcome.
*****Current project is a rechargeable battery (AA and AAA) tester. Charge the battery, put it in the tester, which will discharge it through a standard resistor, and time how long it takes to discharge to a ‘low battery’ level. I need a reliable timebase for that. Basic Stamp (from what I can see, RTFM) uses a temperature-uncompensated RC circuit for it’s clock, so you will get a different result, from the same battery, on a 90 degree day vs. a 70 degree day. Not good. Need reliable timebase. If I’m wrong about the unreliable accuracy of Basic Stamp clocks, hints on timing in Basic Stamp programs are also welcome.