flashlight circuit
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From: Tom Biasi on 27 Jul 2010 11:18 "Michael Black" <et472(a)ncf.ca> wrote in message news:Pine.LNX.4.64.1007271039220.1081(a)darkstar.example.net... > On Tue, 27 Jul 2010, pimpom wrote: > > > The original problem is pretty common, and I sure remember knocking > flashlights about in order to get them working again. > > Michael > For a long time when I was a kid I thought that's how they're supposed to work. Tom
From: pimpom on 27 Jul 2010 16:12 Michael Black wrote: > On Tue, 27 Jul 2010, pimpom wrote: > >> Tom Biasi wrote: >>> "rabbit killer" <siccusproprius(a)gmx.com> wrote in message >>> news:i2kqt6$b95$1(a)news.albasani.net... >>>> why the hell does my flashlight go dim, but when I knock it >>>> hard it >>>> gets bright again? What can I do to fix this? I don't >>>> understand >>>> what's going on here... >>> >>> The bulb is getting less voltage than it needs. >>> Most likely cause is contact resistance. >>> Clean every place contact is made. >>> Battery ends, spring to battery, bulb to battery, switch >>> contacts. A >>> pencil eraser works on most of it. If the switch is sealed >>> you >>> don't >>> need to worry about it. >>> Also check where the reflector rim touches the contact and >>> make >>> sure >>> the bulb is tight. >>> Did I miss anything guys? >>> >> Only the possibility that the OP was trolling. >> > Huh? > > The original problem is pretty common, and I sure remember > knocking > flashlights about in order to get them working again. > > Flashlights are simple, and have virtually no soldered parts. > So the > contact between the bulb and the rest of the circuit is merely > pressure contact, the switches are often on a similar level. > > Those can suffer, maybe the worse because of the current drain > of the > bulb. > > LED flashlights don't suffer because they aren't put together > with > pressure, and there's no surge as the bulb first receives > current and > heats up. > If the OP was serious, I apologise. The problem is so common and the cause so obvious (not only to me, but also to all the non-technical people I know who had experienced it) that I doubted that it was a serious question. Those non-technical types may not be able to explain it as clearly as did Mr.Tom Biasi, but I've known them all to immediately diagnose it with terms like "bad contact", "something loose", "corrosion", "bulb loose in the socket", "weak spring", "worn out switch", etc.
From: amdx on 27 Jul 2010 19:01 -- MikeK "pimpom" <pimpom(a)invalid.invalid> wrote in message news:i2neje$9ik$1(a)news.albasani.net... > Michael Black wrote: >> On Tue, 27 Jul 2010, pimpom wrote: >> >>> Tom Biasi wrote: >>>> "rabbit killer" <siccusproprius(a)gmx.com> wrote in message >>>> news:i2kqt6$b95$1(a)news.albasani.net... >>>>> why the hell does my flashlight go dim, but when I knock it >>>>> hard it >>>>> gets bright again? What can I do to fix this? I don't >>>>> understand >>>>> what's going on here... >>>> >>>> The bulb is getting less voltage than it needs. >>>> Most likely cause is contact resistance. >>>> Clean every place contact is made. >>>> Battery ends, spring to battery, bulb to battery, switch >>>> contacts. A >>>> pencil eraser works on most of it. If the switch is sealed you >>>> don't >>>> need to worry about it. >>>> Also check where the reflector rim touches the contact and make >>>> sure >>>> the bulb is tight. >>>> Did I miss anything guys? >>>> >>> Only the possibility that the OP was trolling. >>> >> Huh? >> >> The original problem is pretty common, and I sure remember knocking >> flashlights about in order to get them working again. >> >> Flashlights are simple, and have virtually no soldered parts. So the >> contact between the bulb and the rest of the circuit is merely >> pressure contact, the switches are often on a similar level. >> >> Those can suffer, maybe the worse because of the current drain of the >> bulb. >> >> LED flashlights don't suffer because they aren't put together with >> pressure, and there's no surge as the bulb first receives current and >> heats up. >> > If the OP was serious, I apologise. The problem is so common and the cause > so obvious (not only to me, but also to all the non-technical people I > know who had experienced it) that I doubted that it was a serious > question. Those non-technical types may not be able to explain it as > clearly as did Mr.Tom Biasi, but I've known them all to immediately > diagnose it with terms like "bad contact", "something loose", "corrosion", > "bulb loose in the socket", "weak spring", "worn out switch", etc. > I'm more used to hearing "it must be a short" from the non-technical types. MikeK :-)
From: pimpom on 28 Jul 2010 05:22 amdx wrote: >> Michael Black wrote: >>> On Tue, 27 Jul 2010, pimpom wrote: >>> >>>> Tom Biasi wrote: >>>>> "rabbit killer" <siccusproprius(a)gmx.com> wrote in message >>>>> news:i2kqt6$b95$1(a)news.albasani.net... >>>>>> why the hell does my flashlight go dim, but when I knock >>>>>> it >>>>>> hard it >>>>>> gets bright again? What can I do to fix this? I don't >>>>>> understand >>>>>> what's going on here... >>>>> >>>>> The bulb is getting less voltage than it needs. >>>>> Most likely cause is contact resistance. >>>>> Clean every place contact is made. >>>>> Battery ends, spring to battery, bulb to battery, switch >>>>> contacts. A >>>>> pencil eraser works on most of it. If the switch is sealed >>>>> you >>>>> don't >>>>> need to worry about it. >>>>> Also check where the reflector rim touches the contact and >>>>> make >>>>> sure >>>>> the bulb is tight. >>>>> Did I miss anything guys? >>>>> >>>> Only the possibility that the OP was trolling. >>>> >>> Huh? >>> >>> The original problem is pretty common, and I sure remember >>> knocking >>> flashlights about in order to get them working again. >>> >>> Flashlights are simple, and have virtually no soldered parts. >>> So the >>> contact between the bulb and the rest of the circuit is >>> merely >>> pressure contact, the switches are often on a similar level. >>> >>> Those can suffer, maybe the worse because of the current >>> drain of >>> the bulb. >>> >>> LED flashlights don't suffer because they aren't put together >>> with >>> pressure, and there's no surge as the bulb first receives >>> current >>> and heats up. >>> >> If the OP was serious, I apologise. The problem is so common >> and the >> cause so obvious (not only to me, but also to all the >> non-technical >> people I know who had experienced it) that I doubted that it >> was a >> serious question. Those non-technical types may not be able to >> explain it as clearly as did Mr.Tom Biasi, but I've known them >> all >> to immediately diagnose it with terms like "bad contact", >> "something >> loose", "corrosion", "bulb loose in the socket", "weak >> spring", >> "worn out switch", etc. > I'm more used to hearing "it must be a short" from the > non-technical > types. MikeK > :-) Oh yeah, that too. But most often in connection with higher power levels than a flashlight. It must stem from the fact that short circuits often produce sparks and burning. So whenever they observe a spark at an electrical joint or contact, they call it a short. And since shorts often result in an open circuit, they sometimes also call that a short.
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