(Earilier posted in .design - moved here by recommendation.)
Many moons ago, I was an electronics repairman in the military. Most tubes had been replaced by then with solid state, which of course was gaining wide use in the commercial world! I was a dabbler in circuitry, and devoured the TTL Cookbook I bought at Radio shack along with any component I wanted.25 years later, Radio Shack is something different and so is electronics. I'm sure E=IR still works, but I'm not sure what they do with it any more! The most I get to do with "electronics" is change a ballast in a flourescent light! Everything seems to be programmed - well, I dabble in VB6 and VBA macros, but that's it. But I've got a couple of things I'd like to see if I can cobble together, and I'm wondering if this is a good place for me to start.
Two projects right now:
Project 1: A digital metronome of sorts. A footswitch that would count the time intervals between successive taps of my toe, average the times, and flash a light at that interval. That would connect to a unit by my hand that would have buttons to increase and decrease the time interval counts. I also want a number pad for direct entry of a number that would set a "beat time".
I'm figuring I would need a stable frequency generator of some kind into a pulse counter. A tap on the foot button would zero the counter and open a gate for about 10 seconds - within that time, every successive tap would capture the number of pulses between taps and increment a tap counter, add the count to the previous one and divide by the number of taps to get the average. The average is fed into a counter that flashes a light after this many pulses.
So far, not bad. I did things of that sort with 555s and TTL up/down counters. But adding and averaging weren't included. And now I want buttons that will increment that count by a plus or minus, and I want to directly enter a count. Which means I also need a display, and I need a circuit to convert whatever the actual pulse count is into something meaningful in my world, and convert my entered number into a pulse count the unit can deal with.
Am I out of my league yet?
Project 2: A comparative thermostatic controller for an attic fan. I live in the Arizona desert and want a fan in my attic to cool things down up there. If I set it for say 120 degrees, the thing will run day and night for months! So I'd lke to compare the attic temp to the ambient temp, trigger it on when the attic raises maybe 20 degrees above and shut off when the temps are even.
I have looked up temperature chips on the internet, but I've never worked with any. I imagine there would be voltage comparators and flip-flops (do they still use those?) to control the on/off.
So how are we doing? Should I be here for help with these? Or over in the "wishful thinking" group?