On Thu, 5 Feb 1998, Robert Nansel wrote: > On 2/2/98 Pasi T Mustalahti wrote: > > -------8<-------- > > > > ------------------------------------- +U (0.6..1.55 V) > > | | > > R20K || < > > | || < > > ----------------> || < > > | > || < > > = 10nF | /------>|--| > > | ----| BC337 | > > | \ | > > | | | > > -------------------------------------- > > > >The transformer is made of a ferrite toroid, size was about 4x3x2 mm (I > >found it from my pocket). I made there about 10 + 50 r (even 10 + 10 > >worked fine). > -------8<-------- > > How many turns did you use on the transformer? What gage wire did you use? > And those dimensions: is that a 4 mm outside diameter, 3 mm hole, and 2 mm > thickness? PTM: Really, I dont know. I found two small toroids from my pocket. Another was black and another was violet. Black was about the size of a asperin tablet and another about 10% bigger. Then I just walked my hands spread and found some wire, about .1 mm diameter and 2 meters long. While I was still walking I wound this wire to these toroids without thinking anything. The transistor I had on my own taple among many others. It looks like there is about 10 turns + 50 turns on the violet and 20 + 20 turns on the black toroid. My frien sain that 1:10 and hard ferrite should be fine, but the device seems to work with what it gets. I connected it to a AA-cell with 1.452 V in it at about 18:00 last friday and left it there. This morning there was 0.73 V and the LED was just as bright as in the begining. So it has lasted nov 7 days (minus 4 hours) and still going strong. The LED is a 3500 mcd device and you can read A4 in its light. It costs about nothing, so you can make some tries. I'm interested if you find some optimisation to this. Or a SIMPLE method to make a current limiter without spending current. -------------------------------------------------------------------------- PTM, pasi.mustalahti@utu.fi, ptmusta@utu.fi, http://www.utu.fi/~ptmusta Lab.ins. (mikrotuki) ATK-keskus/Mat.Luon.Tdk OH1HEK Lab.engineer (PC support) Computer Center OI7234 Mail: Turun Yliopisto / Fysla, Vesilinnantie 5, 20014 Pt 02-3336669, FAX 02-3335632 (Pk 02-2387010, NMT 049-555577) --------------------------------------------------------------------------