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I got circuit #2 finished tonight, finally. #1 went fairly well with a minor switching of the power leads. The voltage regulator heated up pretty good but everything seems to work. #2 then went together much nicer. Too nice! (I don't know if I said or not but I'm building these for a friend that is building two tracks so I need 2 identical circuits.)

I used transistors that I've had for several years. I bought one of those value packs that were all supposedly 2N2222 transistors. All were unmarked. I used 4 for circuit #1 and everything went fine. 4 more for #2 and the lights just did all sorts of bad things. Some stayed on and others blinked in unintended ways. After scratching my head and finding a couple of shorts, I got it to where one set of lights worked and the other 3 glowed dimly (at various levels) while “off”. At 1AM one night last week I desoldered all the transistors and rechecked all the wiring. The wiring was fine. Then I started testing transistors. My crude tests showed all were NPN like they were supposed to be but several from my bin were PNP. Some worked better in my hastily breadboarded test circuit than others. I resoldered 3 more. One more set of lights started working correctly for a total of two. At that point I went to bed and vowed to buy some new ones that were actually known to be 2N2222. Tonight I just soldered the 2 new ones in and the thing works as it should. I tried to save a few cents and spent hours getting it all right. The new ones cost 69 cents each at Radio Shack.

Maybe tomorrow night when I do the woodworking for the start buttons and the mounts for the lights I'll take more pictures and post them. Right now I'm just glad the thing works.
Posted on Wednesday, June 1, 2005 9:43 PM | Back to top

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