I've been working at cross purposes the last couple of days. My little electronics project is such a success it's keeping me from working on it, even as I'm spending time on it!
I''m trying to do all my work now on a test article that I can run on battery power. Some things I can't do that with, but right now I most need to debug the new voltage level detector in that test article. Problem is, a few days ago I began testing to see how long the flasher could run on battery power. I put four new AAA batteries on it, figuring they would last for 20 to 36 hours. Mirable dictu, I'm past 90 hours and it's just reached the 1.3 volt/cell plateau. AAA page, first discharge curve should be the most representative load in terms of curve shape. That means that the flasher should run for 440 to 480 hours on these tiny batteries, and over two thousand on the C cells I mean to use it with! That's darn good--flashing hours won't take as much as I feared from battery lifetime--but I'll have to cut this test short to get work done.
I also have to work on my much-modified "pigeon" flasher--but I don't want to get tied up in that until I have the detector working. I also have a start-up problem on the flasher: when it's turned on the capacitors draw so much current to charge that the voltage drop resets the timer. I think I can fix this with a resistor that will slow the turn-on of the MOSFETs that feed the flasher. It's just a matter of finding the right value. Thing is, I want to test the fix with the cheapest carbon-zinc batteries I can get my hands on--and it's getting hard to find them nowadays.
And then the pigeon flasher. I promised to send the final circuit drawing to the guy I cribbed it from. It's a surprisingly subtle design that can maintain a steady flash rate over a wide voltage range.
But right now Im going to work on Chapter 4, and then I'll see if I can find those cheap batteries.
From Maxell ad of 30-odd years ago: "With some tapes, you can't tell your brass from your oboe."
My favorite: "He can't tell a burro from a burrow!"
