Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: jhadhar65 on January 31, 2009, 07:06:00 pm
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Here's a simple situation that I can't get my head around:
PRR mentioned something quite a while back on a thread that's now lost to me. I didn't ask immediately, since I figured if I studied on it a while on my own, the answer might become obvious. I tend to better remember lessons learned that way.
Anyway, you were giving advice to someone building a limiter and you said use full size bulbs, not mini's. I've thought about that quite a bit and I can't seem to figure out why not. The only thing I can think of is input voltage will be whatever it is and that, together with the bulb's wattage rating, will dictate the bulb's current draw and resistance whether you use a regular size incandescent or a teenie one, right?
There's something I'm missing, I know, but it's not coming to me. As I type this, it occurs to me that you might not have meant always use big bulbs in every application, but there may have been something unique in that particular thread/situation that would make a big bulb the best choice. I hope that's not the case because I can't locate the thread now and you might not even remember what I'm babbling about.
The deal is, I've got pretty limited bench space and my limiter is bulky and hot. I've been eyeing Weber's solution (https://taweber.powweb.com/store/kits_weber.htm#safestart), which would really help me reclaim some much needed real estate, but I've not pulled the trigger on it because of the small bulb issue.
PRR, do you remember this and/or what are your thoughts on it?
EDIT: OR... did you mean 'big' as in 'high wattage'? That never occurred to me until I read through all this drivel I just wrote.
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Incandescents, NOT "compact fluorescent incandescent-replacement lamps".
You want a skinny piece of tungsten, NOT an electronic contraption feeding a gas-tube.
That went without saying until a few years ago. Now, somebody is likely to think "lamp is lamp and CF is best".
Lamp power similar or somewhat higher than expected amplifier power consumption. If similar (60W lamp on 57W-input Champ), you won't get near full voltage to the amp, but smoke won't happen fast. If you need to make extended semi-realistic measurements on a very-sick amp, use a larger-Watt lamp, but smoke could happen fast.
The physical size is unimportant. Since it is in a 120V line it must be a 120V lamp. Since it will generally be in the 45W-150W range, standard household lamps are the obvious choice. I suppose you could use a miniaturized hard-glass Halogen kitchen-spot, or a giant PAR, but why pay that much?
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Okay, I got you. Ted's uses a very small halogen - not the spot kind for track-types. I haven't priced those bulbs, though. Thanks for the good memory. Igor the Light Bulb Limiter is about to go under the bench as a spare.
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I used a 60W bulb on an SVT today.......damn thing stayed bright the whole time..........and there was no short in the crct.... ;D ;D ;D
Bl
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I'm only surprised the rest of the bulbs in the house didn't brighten up!