08/01/01
With many profuse Thank-You's to my co-worker Jeff for giving me a clue about electronics, and Marcus for taking the time to give me some sample circuits, I've actually got something constructive going on here. :) I've been reminded of Ohm's Law ("Oh yeah.."), and learned that LEDs work more as a function of current than voltage. I know many easier circuits exist, but my knowledge of NAND gates and their use is rough enough that I decided I'd rather build something I can test with the kit I have on hand; if I wanted to build the supreme flashing circuit I'd put a lot more time and experimentation into it, but what I want is a supreme ship, and therefore will run with what I have so that I may test it with minimal parts purchase / experimentation. The Radio Shack kit has a sample circuit for a strobe light, which I constructed but there were a number of problems - it flashed too quickly, and it simply wouldn't work with a white LED. In talking with Jeff I learned enough that I could modify the circuit they had (and take out some superfluous parts) to not only make it work with a white LED, but slow it down. I increased the resistance before the capacitors (1) so they wouldn't charge as quickly, decreased the capacitance of (2) so it would work with a white LED, and increased the capacitance of (3) also to slow the flash rate. Here's what I came up with:
1 - 690k Resistor 2 - 0.1 uF Capacitor 3 - 200uF Capacitor 4 - 2SC945 NPN Transistor 5 - 900CT:8 ohm Transformer 6 - White 3.0mm LED
With the above configuration, the white LED flashes at an excellent approximation to the Voyager's running lights. The only problem I have is that if you examine the LED carefully, you'll see it start to glow before it flashes. Going through fibre, however, that's not much of a concern.
Now I need to design the circuit as a whole - I need a 3v transformer to power the whole thing - half of it will be the circuit that powers the full 3v / 20 mA LEDs as well as the 2v (unknown mA) smaller LEDs, and the other half will be the flashing circuit that powers the white LED fibre driver.
A trip to RadioShack.com is in order, to get the specifications of the smaller LEDs, acquire green, blue and red LEDs and get the mA rating of the white LEDs. I also need to acquire more fibre cable (though I can't get that from the store, need to go somewhere else).
Here's my shopping list: (23+ LEDs total)
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