Cheap Dummy Load Resistors

[R.G.]

Marlin P. Jones and Associates (http://www.mpja.com/) has a special on 2 ohm, 120W (!) resistors for $2.95 each. I believe the special is good for a week.

They also have 4, 8 and 16 ohm 120W resistors for $6 normally.

[Enzo]

Cool.

I always think of them as a place that sells power supplies. I forget they sell other things.

[Wombaticus]

Marlin P. Jones and Associates (http://www.mpja.com/) has a special on 2 ohm, 120W (!) resistors for $2.95 each. I believe the special is good for a week.

They also have 4, 8 and 16 ohm 120W resistors for $6 normally.

Picked up four, but the cheapest shipping option turned out to be another $10. Still a decent deal I guess, considering Mouser charges something like seven bucks for a similar 2R 100W Vishy Dale.

[Wombaticus]

Picked up four, but the cheapest shipping option turned out to be another $10. Still a decent deal I guess, considering Mouser charges something like seven bucks for a similar 2R 100W Vishy Dale.

OK! The mystery of the seemingly high shipping fee is solved. These arrived today, and they are HUGE and HEAVY. The barrel of each one is 6.75 inches long(!), with a diameter of 1.25". These are seriously-no-fooling-around power resistors.

[Wombaticus]

So, yes, the dummy load I constructed from these resistors should handle just about anything you might care to throw at it. In fact, the first thing I used it for was a 300W Ampeg SVT-VR.

[Randall]

NICE! How is it wired up?

[Wombaticus]

NICE! How is it wired up?

It's wired to either be in a series/parallel arrangement totaling 2 Ohms (good for the SVT bass amps, which have a 2 Ohm tap), or just all in series for 8 Ohms (good for most other things).

[Randall]

One could probably wire it with one 3way switch to get a 4 ohm load as well, no? Dang, I missed that sale by a couple of days. I had designs of making something very similar.

[g1]

I'm a little queasy about that wire at 15 amps?

[Wombaticus]

I'm a little queasy about that wire at 15 amps?

Ehh..i'm not too concerned for what I'm doing. It's 20 gauge solid core, which is rated at 11A for general chassis wiring. It's true that with 300W (most I'll likely ever need) in a 2R load you're looking at something like 12.25A... But it's only a couple of inches of wire, and for only a minute or two at those currents. To keep things in perspective, the 10s fusing current for copper solid-core 20 gauge is nearly 60A.

[g1]

Wasn't sure what your usage would be so I thought I'd check.
With 480W of power handling you could be running some SS power amp or something for more than a couple minutes, maybe as a shop heater or some such .
If it gets too hot it could have quite an effect on the load resistance.

[R.G.]

To keep things in perspective, the 10s fusing current for copper solid-core 20 gauge is nearly 60A.

And in any case, the gentle aroma of vaporized PVC insulation will act as a warning of running near max power long before the wires themselves melt.

[Regis]

I've been looking at those. I've been wanting to get a few and build a couple of simple guitar amp attenuators for cheap.