The Biggest Rheostat You've Never Seen.

[@Apismeliffera]

Biggest rheostat I ever saw in person was backstage in high school. Six feet in diameter with the resistive elements made out of cast iron. There were six of them in a row and they were used to adjust the brightness of different stage lights. You moved a hand lever up and down to turn it. I looked but didn't see a name plate. I would have liked to know what the total resistive range was.

[@BadDogElectronics]

That's crazy. I would like to have seen that.

[@laserhawk64]

Slight correction, if I may, rheostats are two-terminal, pots are three-terminal. You don't have a three-terminal rheostat. The power handling's nothing to do with it. Your "2-1/2a rheostat" is a 2.5a-rated wirewound potentiometer. Oh, and the rheostat with the "off" spot? I about guarantee it's got a log taper, too -- specifically an _audio_ log taper -- rather than linear. Wirewound pots and rheos like that, those were common on old tube radios and the like. I've got a 30s-era blooper set (it needs a replacement tube, but otherwise it'd work fine) that uses one of those. Also, no, those terms _are_ specific and not synonymous or fungible. However, if you need to specify something as "either a rheostat or a potentiometer and it doesn't very much matter which", you can simply call it a -- "variable resistor"! ;3 But, hey, for the most part, great vid and tutorial.

[@BadDogElectronics]

Thanks for the comment & compliment! A quick search of wiki reveals however that "Rheostats must be rated for higher power >1 watt" & "They're made to adjust a magnitude of current...". also, they can have 2 or 3 terminals. Though the 3rd, as you mention, is just a tap to give you a variable resistor. Lastly, it's hard to argue with the manufacturer of the 2 1/2 Amp Clarostat. It says right on the label, Rheostat. Thanks for the info on the LOG tapered pot as well. I suspected it was from a tube era radio. If you can't find the tube you're looking for, let me know. I have one or two around here ;)

[@laserhawk64]

@@BadDogElectronics Please don't argue with me on my birthday... The tube's a #99. It's like $10 on eBay, I'm just a cheap b@$%*^#, lol. But, hey, I accept donations, if you want to offer that.

[@BadDogElectronics]

@@laserhawk64 lol okay! Happy Birthday!!!🎂 EC99's are indeed pricey, but they are plentiful too. I was assuming you just couldn't find the tube you needed. Enjoy your day!!!

[@frrapp2366]

i actually saw one for a train turntable if i remember right i think it was about 6ft around , the table is now gone but was very cool

[@BadDogElectronics]

Very cool! I first thought this was for a train. Then I saw NAVY. They have all the good stuff! ;)

[@kerryhagerty7051]

That would be a fun knob for something. 😎

[@BadDogElectronics]

I think it'd make a great knob for a pizza oven. 🍕

[@thomaswojcik3402]

We have one boarded up in my church, started smoking a number of years ago and we went for individual switch dimmers. (we dont have historically great luck with fire) unfortunately someone sawed the handle off but its still in the wall just covered by a board 🤷‍♂️

[@BadDogElectronics]

Wow...a dimmer. For it to start smoking, That's some pretty serious lighting ;) Some time in the distant future they'll find it during a renovation. Someone will think it's some mysterious tech. lol Thanks for sharing!

[@john-mi1ud]

largest rheostat i've seen on youtube is photonicinduction's

[@sammy5576]

are you sure you aren't thinking of a variac?

[@BadDogElectronics]

I'm gonna go check that out! Thanks

[@Roobotics]

6:53 That's not entirely true! For the sake of the demonstration it's mostly doing nothing. But your meter is bouncing a bit and that's not just random noise. The wiper is occasionally shunting two adjacent windings due to how they are constructed to overlap and 'make before break' of each connection. So the wiper is having a measurable effect. Technically it's also a capacitive node moving down an inductor and has RF connotations like tuning.. but that's more a tangent and less measurable or important in practice. 14:01 Don't you mean the resistance will go higher? Identical to above, the band is shunting 2 resistant windings, so removing the shunting metal will make the resistance go up. I wouldn't expect a power rheostat to have amazing tolerances TBH, but if it actually goes down towards 50, I'll eat my non-existent hat, or at least be very confused.

[@BadDogElectronics]

You are totally correct. That is my reason for the "nothing substantial" text @ 14:21. I think to explain that the wiper is shorting some windings and increasing the resistance is splitting hairs. While it does affect the measurement, I opted to keep as little mud out of the water as possible😉 Lets face it, if you know, you know. Good eye though!

[@rahulbhaskar4179]

Sir, can we make a test load with a rheostat

[@BadDogElectronics]

Yes, I use a rheostat as a load often. Just make sure you don't exceed the power rating of the rheostat. P=VxI.

[@sammy5576]

most of the small pots are 0-infinity logarithmic, especially for audio or signal

[@BadDogElectronics]

Thanks for sharing.

[@A181218121812]

If still in use, the liquid rheostat's that NASA uses at the National Transonic Facility to vary the speed of the wind tunnel dwarf the rheostats that you have. They have 3 of them. They are something like 6 foot in diameter and 18 foot tall.

[@BadDogElectronics]

That sounds pretty big. Thanks for sharing!