Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: kagliostro on January 19, 2024, 02:47:46 pm
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Nowaday incandescent lamps (here) are difficult to be find so I'm afraid to be not able to find one if my Lamp Limiter bulb fails
With that in mind a question appairs
Is it possible to arrange a Lamp Limiter using common 12V car lamp/lamps ?
and, if so, which will be the correct lamps to be used for 5-10W, 15-30W and 50-100W amps ?
Thanks
Franco
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Can you get halogen type incandescent lamps? They work fine for this purpose.
I've also been able to buy incandescents off eb_y. In fact my current limiter uses a 250W photo flood (ie 2A) that I purchased about a year ago.
12V car lamps are probably not a good direct replacement, even at the same power dissipation. I don't know how the filaments are designed, but I would bet the lamps would burn out at startup.
In the US, we do have continued availability of "appliance bulbs" in the stores which are usually 40 watts (ie, they pass about .33 A at steady state). I guess if we ran three of those in parallel we'd be limited to an amp.
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Thanks acheld
Also 240V halogen lamps are dismissing here, only car lamps are easily available
Don't know about photo lamps, I must ask
About the use of car lamps I was thinking to someting like to use them in junction with resistors, not alones
Franco
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More fun because your "here" is Europe, Italy, 220-240V land. (Cars have been all 12V most of our lives.)
Use a toaster or a coffee-pot, it will prevent burning wall wires or tripping circuit breakers.
Ten car-lamps in series would be fine on 120V power, but on your 220V power you would need 18 or 20 car lamps.
In the US: the stop lamp is usually1.5 Amps. So 20 in series makes a 360 Watt "lamp" and would be fine for most smaller amplifiers. Headlamps are 36 to 48 Watts so 3 or 4 Amps, thousands of Watts, good for very large amplfiers. But that's a lot of sockets and wiring. (Your lamps may be less because historically smaller cars and fewer very-long highways, but I know you know how to find the numbers.)
Car lamps do "go out of style". Note that my 2023 car has almost no incandescent bulbs. Since I was a boy tail-lamps were 1156 or 1157. I have half a drawer in the garage. I recently realized that NONE of the cars that have lived here, even a 1986 truck and the 1991 MX5, and a 1996 and a 2002 and now a 2023, use 1156/1157 lamps. If I needed some, I might go to every parts shop in town and still have to wait to the next day. So if you do car lamps, buy a lifetime supply now.
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European trucks can use 24V headlights rated 70 Watts. So ten of those series is "700 Watt bulb". Since you won't run full brightness for long, you can just solder wires, no sockets.
https://www.truckelectrics.com/products/24v-70w-h1-no-466-pack-of-1
24v 70w H1 / Hella / No 466 / Pack of 1 HellaSKU: 140466 Price: Sale price €2.50
So ten would be €25 on sale.
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eBay Italy:
https://www.ebay.it/itm/385332451062
"Special Purpose, shock vibration"
LAMP INCANDESCENZA FILAMENTO 100W 230V E27 (kit 10 pieces)
EUR 9.90 (ten-pack?)
99 available / 185 sold
L'oggetto non viene spedito a Stati Uniti.
Oggetto che si trova a: Plaus, Italia
Plaus Italy is a tiny place way north of Trento. I don't know why they picked that destination.
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Ciao PRR Many Thanks also to you
I think that those 100W 220V lamps are warehouse funds and someone is trying to sell it
despite that it is a good chance
Franco
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There seem to be a LOT of incandescent bulbs on ebay.it.
But I also see a lot of "Tipo Incandescente" with "Classe di efficienza energetica A" which are certainly LED bulbs made to look like incandescent.
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I just got 1 x 100W and 3 x 75W at a flea market
Franco