Bulbs to avoid in current limiter

[Fritter]

Hi all,
Just putting my first current limiter together (uk). Apart from led's, are there any bulbs that will not function as needed? Any advice much appreciated.

[eccerr0r]

Re: Bulbs to avoid in current limiter

Just has to be some sort of blackbody long lasting heating bulb, so no LEDs, no CFLs. no neon bulbs, no flash bulbs, or sodium lamps to name a few.

A suitable resistor or cup heater will work too, but they don't glow

A blacklight bulb would work too but hard to see it glow which is kind of important. Otherwise incandescent and halogen lamps are perfectly fine.

[stj]

Re: Bulbs to avoid in current limiter

i use linear halogen lamps - mostly because shops are trying to get rid of them for beer money
they go from 80w/120w for the really short ones, to 300-500w for the medium ones and even into Kw for the big ones - but those are rare.

[redwire]

Re: Bulbs to avoid in current limiter

I don't like using halogen lamps (in testers) because their hot/cold resistance is really a high ratio.
I think it's 10:1 for ordinary lamps but halogens run so much hotter their cold resistance is really low and not much current limiting, I'll bet it's over 20:1.
We talked about this in some other thread on dim bulb testers.

[megaraider]

Re: Bulbs to avoid in current limiter

i use linear halogen lamps - mostly because shops are trying to get rid of them for beer money

The same applies for incandescent lamps Though the most common are under 100W.

[petehall347]

Re: Bulbs to avoid in current limiter

avoid broken ones at all costs .

[redwire]

Re: Bulbs to avoid in current limiter

They just smoke a little but glow just fine

[Fritter]

Re: Bulbs to avoid in current limiter

Thanks for advice. Difficult to find incandescents at the correct wattage without a remortgage. I've resorted to going round elderly relatives and paying for new bulbs for their old gear

[stj]

Re: Bulbs to avoid in current limiter

you can run several lamps in parallel to get higher wattage
what are you looking to get?

[momaka]

Re: Bulbs to avoid in current limiter

I don't like using halogen lamps (in testers) because their hot/cold resistance is really a high ratio.
I think it's 10:1 for ordinary lamps but halogens run so much hotter their cold resistance is really low and not much current limiting, I'll bet it's over 20:1.
We talked about this in some other thread on dim bulb testers.

True.
But for testing PSUs with APFC, sometimes it really is better to use a halogen bulb than regular incandescent. Otherwise, the APFC might not be able to "pump" current into the APFC inductor properly. And even though the cold resistance of halogens is very low, it still won't be bad enough to blow fuses - at least fuses for medium-large size PSUs / devices. Obviously if you are testing "small" power supplies (under 50W I'd say) and power adapters, 40-80W incandescent or 35W halogen might be just fine.

In that respect, the locale voltage also matters too - i.e. 120V vs. 230/240V AC. With the latter, even if the voltage drops to half (~120V AC) due to the series bulb and a load on the PSU, the PSU should still be able to function if it's "wide range" type (typically discontinuous/flyback topology.)
So in short, 230/240V can be more forgiving with a series bulb, depending on the device under test (DUT).

With 120V AC, I often have to use really high-power heating elements if I want to test PSUs at low-to-moderate loads. Typical figure is about 10-15% of rating of the heating element - i.e. if I want to pull 100-150 Watts of power from an ATX PSU, I typically need to change out the "dim bulb" device with a 700-1000 Watt heating element. Any less, and the input AC voltage drops too low for the PSU to continue functioning.
Again, with 230/240V AC, this is not as much of an issue, as "wide range" and "full range" (APFC) PSUs can still work fine even with the much larger voltage drop.

you can run several lamps in parallel to get higher wattage
what are you looking to get?

+1

40 Watt "appliance" incandescent bulbs will likely never go away. In appliances where there is a lot of heat (i.e. dryer, oven, MW oven), incandescent bulbs are still the only option. So you should still be able to find those in most home improvement stores. Just go for the cheapest one. Only issue after that, however, might be that the socket might not be standard. But that's what a soldering iron and wires are for!

And yes, when you parallel several 40W bulbs, their power adds up. So 2x 40W in parallel = 80W equivalent bulb. And 3x in parallel = 120W equiv.

avoid broken ones at all costs .

But don't you know how many purpose a broken bulb can have?

MR16 / GU10 halogens can be cut out and turned into flash lights / bike lights. Just cut out the old halogen bulb out of it and replace with an LED.

And the old "pear-shaped" and round globes can make for cheap / budget / DIY Christmas ornaments. After all, nothing says it more loudly that you're an electronics tech/EE than home-made Christmas ornaments from dead incandescent bulbs.

As for CFLs - those make for good inverter testers for LCD monitors with CCFLs (does anyone even still repairs these?) And the electronics / components inside them make for decent test spare parts sometimes, provided they weren't burned to a crisp (often the case.)

[megaraider]

Re: Bulbs to avoid in current limiter

MR16 / GU10 halogens can be cut out and turned into flash lights / bike lights. Just cut out the old halogen bulb out of it and replace with an LED.

I do like your idea to reuse... except when it's more expensive than buying a new led bulb (either MR16/GU10)
But i've made the inverse: salvage an old halogen case to replace in a working led one