> >> I used a 60W 230v lamp in series with a 110v valve clock radio when I was >> about 9 years old. I couldn't afford a transformer. It worked amazingly >> well >> but the clock was always slow something to do with the frequency and a >> synchronous motor that didn't like 50 Hz. It always started bright and >> went >> dim as the valves warmed up. Never figured that out ... Just like the lamp, the valves' filaments resistance increases as they warm up. The main use for lamps as limiters is for their highly nonlinear current-resistance characteristic as the filament warms up, so they drop minimal voltage at low currents when cold, but limit current significantly as the increased current heats the filament up. They also provide a handy overcurrent indication by lighting up. Not too different from modern polyfuse devices. (except they don't light up, at least not unless you REALLY overload them!) >> It works as a voltage divider so it should work as a current limiter as >> well. The also make good RF dummy loads. >> >> Steve >> >> -----Original Message----- >> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf >> Of >> Harold Hallikainen >> Sent: 04 January 2007 15:58 >> To: Pic List >> Subject: [EE] Incandescent Light Bulb as Current Limiter >> >> I'm considering using an incandescent light bulb as a current limiter in a >> circuit, but having trouble finding voltage versus current data for light >> bulbs. All my Google searches turn up consumer info on people that want to >> sell me light bulbs. Using the term ballast turns up stuff on fluorescent >> lamps. Using constant current turns up stuff on LEDs. So, anyone know >> where such data may exist? >> >> THANKS! >> >> Harold >> >> >> >> -- >> FCC Rules Updated Daily at http://www.hallikainen.com - Advertising >> opportunities available! >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> >> >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> > > >-- >FCC Rules Updated Daily at http://www.hallikainen.com - Advertising >opportunities available! -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist