PLEASE READ: I made a mistake when I said that detaching the ground would make this into an isolation transformer. IT WILL NOT. After checking for continuity between the outlet and the plugs, the IS A DIRECT connection. I am sorry for my mistake.

@Whopperjaw.

4 жыл бұрын

Now you tell me 🤯

@englishrupe01

4 жыл бұрын

@@Whopperjaw. Lol! You join the Tingle club?lol! Hey, i have had one or two Tingle's from 3-phase 440v in my more stupid youth many decades ago! That'll make you take notice.....probably took the last of my brain cells with it too.

@jimwoods9551

3 жыл бұрын

Was there ever an isolating variac, surely a contradiction?

@noelconway2589

2 жыл бұрын

@@jimwoods9551 Actually Jim there is ! Variac have produced a variac and isolation transformer in the one unit. I saw it recently on a KZread vid but I cannot recall the channel. It's worth checking out .

@Onkel.Moetrik

Жыл бұрын

@@jimwoods9551 it must be possible with a couple of transformers after the variac..😀

For using a variac in an electronics lab it's best to put the output of the variac into an isolation transformer.

@noelconway2589

2 жыл бұрын

I would not agree Guidok. Isolation transformers are designed to operate at their designated voltage. If you connect a variac to the input of an IT the inductive reactance especially at low voltages will generate serious heat issues as the IT tries to overcome the induced voltage in it's windings. I use the IT first then the variac and then the dim bulb tester. It is just a personal choice and is not a criticism of your method.

@mrpetit2

2 жыл бұрын

@@noelconway2589 Yes that would be the right way to do it. 👍 If you look at adjustable isolation powersupplies from the company Thalheimer (one of the few that specialize in these), they are mounted in this way too.

@noelconway2589

2 жыл бұрын

@@mrpetit2 will check them out Guidok thank you .

Paul. Removing the ground wire from the output connector will NOT make that an isolated transformer. The line pin will still be referenced to power line ground, and if it was connected to the chassis of the device under test, and you touched ANY grounded surface, you would get your eyeballs caged, for certain. A true isolation transformer has a secondary with no reference to power line ground.

@manosif

4 жыл бұрын

Agree. You can't isolate an autotransformer.

@learnelectronics

4 жыл бұрын

You are correct my mistake.

That's why they torque the screws so hard, so you don't see what a bad job they did on the inside.

@whatsstefon

4 жыл бұрын

Brought to you by Chinesium Inc.

@jimwoods9551

3 жыл бұрын

The screwdriver is so knackered I can see the wear in a thumbnail. Slag off the manufacturer all you like, but cheap is always cheap, what do you expect?

Enjoyed the video, it's been a long time since I've use one of these. Yeah, I ordered some components and I'll hopefully see them in April. Thanks Paul.

Thank you for the tons of videos you do man. I really enjoy them

Thanks for demo on how to hook up scope to check mains. Good job as usual.

Thanks Paul, take care!

FYI thank you for channel Question....is the charging of 12v SLA battery consider a resistive load?

I think their called VFD variable frequency drive no?

Nice. Thank you. Have a great day, sir.

Take care in these difficult and dangerous times Paul. Is the variac the only way of obtaining variable AC voltage? Or could this be done electronically?

"We live in strange times" I couldn't agree more and still rings true today in many ways lol, great video Paul, I have the same variac on my bench and it was cool to see the insides. I want to wire my own house!

I was watching a video on setting up an audio technicians workbench. They were using the BK Precision Instruments 1655A AC power supply. Does this perform the same function as the Variac? There is a considerable price difference between the two. I’m new to electronics so I’m just learning this stuff.

I was going to use a scope to trouble shoot my radio building, but then I realized if anything is grounding a portable am radio with ferrite antenna battery powered, I cant tune it right, do you think rf energy is absorbed into oscilloscope probe?

SO, will this slow the speed on like a hand held or bench top grinder? Thanks!

I have 3 amp version of this variac, it's supposed to have a slow blow fuse in it but when I checked, it's a fast blow type, would you use a slow blow for it? my second question : what happens is I put a 5 amp fast blow in this variac? thanks.

Just bought this variac. Tested the socket of the transformer and found continuity of neutral with the hot lead. Is it normal? Tested on a tool and worked. Is it safe to use?

Thanks. Stay safe

Silly question. Where do you put the Vairac when using a isolation Transformer/Dim bulb load limiter set up? Before or after the isolation transformer? So is it Line in -->variac --> isolation Trans-->Dim bulb -->load or Line in ->isolation Trans-->Variac -->Dim bulb -->load or Line in ->isolation Trans-->Dim bulb-->variac -->load and the hard part why?

whats the difference between a linear power supply and a variac?

If your going to get into restoring old valve radios or amps i think one of these and an isolation transformer would be near the top of your shopping list . I watched a video from EEVBLOG about protecting your scope in this respect and iirc he also touched on how some smps are not isolated from earth either . Thanks for the video !

This device was always a curiosity to me and never saw the inside before (thanks for breaking it open). Like you mentioned, always careful hooking up scope knowing the outer bnc is grounded.

The same goes for the scope: it is either powered by battery or one uses a 1 to 1 transformer to insulate its power supply. I liked the variable amplitude sinewave (this is what an autotransformer is good at), it also means you' ve got a good power suplly neighborhood.

I believe the input and output share the same neutral, so simply removing the ground still wouldn't give isolation. Isn't that right?

I bought the same Variac as you in March or April about a month was projected so I finally found someone who had it in stock in U.S.. 1 1/2 weeks. I also added a power LCD Monitor which came from China on a slow slow boat LOL. It reads Volts, Watts, Amps, PF, KWH and Hz. I have to tap 1 leg and lift, of a 0.1uf Cap inside the LCD Meter, wire the leg to the Top of the Fuse Holder inside the Variac front cover to have Full V readout from "0" to Full V. Right now it kicks in at about 55V.

I am so glad you made this video. I purchased one of those thinking it was an isolation transformer. I could have wrecked my oscilloscope. Thank you so much. I will need to do some tweaking before I connect any scope ground connections.

@rmark1083

3 жыл бұрын

No tweaking needed just use a cheater plug.

The ground in the fuse box is tied to the neutral wire?

Mr. Gator is protecting the O'scope from that dangerous Variac.

"Don't touch your face" I remember that moment in history

Is there a 220 volt unit?

what is the difference between a transformer and an autotransformer?

I have a question. On my Variac with the switch on and voltage set to 0 volts. Both leads coming out of it are at 125 volts in relation to the house ground. (Both the live and neutral from the variac). Is this normal or is it miswired? Thanks for the help.

@learnelectronics

4 жыл бұрын

doesn't sound right to me

Could you install a switch for the ground so that it would be an isolation variac when you need it? Then turn the switch back on for safety.

@learnelectronics

4 жыл бұрын

It would take a little more than that, but it could be done.

Hey Paul. I have a question. I'm working on an unregulated power supply with extremely smooth ripple and very few components. The load is very stable but is adjustable. Im trying to figure out the best way to incorporate a simple led power indicator but the resistor seems to be interacting with the circuit and the led current has a large range depending on the load and voltage I set. Is their a good way to do this?

@learnelectronics

4 жыл бұрын

You need a buffer. Use an opamp like an LM741 with unity gain.

@Spentelectrons

4 жыл бұрын

@@learnelectronics took me a second to figure out what you meant. I'm actually designing the power supply itself to learn how it all works.

1.2 gigawatts! Thanks for the video. Keep healthy Paul.

Variac, is a trademark for an variable autotransformer made by General Radio, up to 2002, or Instrument Service & Equipment, since 2004. Just thought I'd share that.

Good stuff there Paul. 😁 I ordered some electronic parts a week ago and they should be delivered April 17th. It's like buying stuff from China. Thanks for the video and stay safe!

@learnelectronics

4 жыл бұрын

You stay safe as well!

I have this Variac. Works well. Most annoying thing about it is the paint / ink they used on the switch to mark I / O has rubbed off and like yours, the analog meter isn't accurate. Meh, you get what you pay for.

its been a while.. if not grounded be sure to have double insulation (eg potted transformers , joints two layers of isolation .. at least) and take safety precautions. Thanks for the warning about the mistake.

I bought one with very bad cold solder joints, good thing i was curious and looked inside! Without detail, I will say it was dangerous. as well suggest anyone who buys one to inspect the innards! Mine is ok now.

Sounds quite unsafe and obsolete to tie ground to neutral. It would mean that if anything happens to the neutral conductor after that connection, every metal applience that is grounded becomes live on the outer casing. It's better to use a true earth pin imho.

Amazon pretty much sucks these days! I have been finding parts on eBay and getting them quick by finding them in my state or close by, many cheaper too...

@learnelectronics

4 жыл бұрын

Same here. All my shopping has gone ebay!

What would happen to the appliance if the frequency would change?

@learnelectronics

2 жыл бұрын

depends on the complexity of the appliance. A dishwasher would probably work, but the timing would be off. An old school washing machine with a mechanical timer would be fine. A new one, like the Samsung smart washers wouldnt even boot up.

@itrstt66

2 жыл бұрын

@@learnelectronics where can look up on mechanical timers or is there any other keyword to look for?

I was just going to comment about your claim concerning isolation by removing the ground wire until I saw your disclaimer below. But I did want to make two points. First of all the ground connection on the output secondary is really not the issue. There is no need to connect your DUT to that ground connection. Just use a cheater plug if necessary. The real problem is that the secondary neutral is earth referenced because it is shared between the primary and secondary windings and the primary neutral is bonded to earth ground both at the distribution panel as well as the (pole or pad) supply transformer in the street. Another problem that sometimes arises (particularly with medical isolation transformers which this is not) is that, even though the primary and secondary neutral are not shared, there is a connection between the neutral and earth ground on the secondary. This is done to isolate against noise. Many Tripplite "isolation" transformers are like this. Removing THAT connection will render it a true (tech) isolation transformer. Also there ARE variacs that have true isolation between primary and secondary windings (do not share the neutral). Here's a link to a youtube video about this (note that it specifically references that it is isolated): kzread.info/dash/bejne/f6F1j7SLmLO3ctI.html. As an adddedum I should add that the reason the primary and secondary share the neutral is because an autotransformer has only a single winding. Variacs that are isolated accomplish this by having 2 separate windings as is typical for most transformers.

Just google "Variable Isolation Transformer" if you want to see a proper variable isolation type transformer/variac.

I run into a surprising high amount of ac circuits with reverse polarity in peoples homes. It's dangerous at times because I get shocked when I'm in a hurry assuming it's wired right 😂

ground loops scare shit outa me!!

Whats a variac ? A lethal weapon ... wheres me mask ?? 😱 😎👍🍺☘

You win the Internet by mentioning EVH ✌

I was fortunate to score a TEMCo TVT001 variable transformer at an estate sale last year. Eleven pounds of Made in the USA quality. Data sheet: www.alltronics.com/mas_assets/acrobat/28N099.pdf

Standard Chinese craftsmanship

Shenzhen is a good place. 😀

Okay so I don’t know a lot about voltage, amps, etc. I’m a home coffee roaster and I have a few electric roasters that I use in my garage. All the instructions say don’t use with an extension cord or a line that other appliances are drawing from. The roasters are small household appliances similar to a toaster oven. They say you should plug directly into an outlet so you don’t lose power to the machine which means a longer roast time that can comprise flavor. Unfortunately my outlet is on the ceiling and I have to use an extension cord. These machines never produced the results I was expecting probably due to using an extension cord and a loss of power. I have heard of people using a Variac but I never researched it until now. Would a Variac solve my problem? I’m just looking to plug in one machine at a time and get full power. I’m thinking if I plug the roaster into the Variac and bring it up to 120 or so then I should be getting full power to the machine. Is this correct? Do you think this will solve my problems? Thanks for any suggestions.

@learnelectronics

4 жыл бұрын

I would not advise using a variac to boost your voltage unless you increase the diameter of the extension cord. Maybe 12AWG.

Use a cheater plug for devices that contain a grounding plug and you'll be isolated and without soldering.

He thinks they make screws on lathes. 😂🤣🤣

Here in Europe, earth is not connected to the neutral. Just to point out some local differences

@peterdegelaen

4 жыл бұрын

Right. In fact, it is forbidden to do that. The house ground wire (or earth wire as it is called in the UK) is connected to a local earthing loop. In modern houses (in Belgium, since approximately 1981), the foundations of the house should contain an "earthing loop" and that is connected to the outlet's ground connections. The neutral is connected to the earth in the network substation but the neutral and the ground are NEVER connected to eachother in the local house installation.

You need a new, correctly-sized screwdriver.

Re: Amazon shipping. I ordered an item Thursday, 3-26 and got delivery 3-29. Pretty good standard shipping.

NOT a good Idea to Connect a Scope like this. The Old School Scopes use actual House Ground.

@learnelectronics

4 жыл бұрын

Thats why I warned everyone

Another quality Chinese product. I have one too unfortunately. 😬

Sum Yung Guy! xD

You were “about” to wonder about the quality?? You didn’t know by the price and origin of manufacture?? L

My friend, this variac can never be a isolation transformer. "Isolation" by the term means that the Primary and secondary are NOT physical connected, that is not the case in this red donut. Every stage of the variac is connected by carbon brushes, hence No! No! No! Isolation.

3:47 typical chinese crap quality. I was originally going to ask if that was from Harbor Freight but seeing it more I doubt it. Looks like Family Dollar is now selling these. things. 😄

For the love of screwing around and screws in general.. get a quality screwdriver! And NO, removing the earth doesn't make it a isolation transformer! You loose viewers that way, in a bad way!