Clamping soldered wire in screw-terminal connections is a reliability risk due to thermal expansion/contraction, the solder will slowly cold flow under the screw pressure, resulting in a loose connection eventually. The proper solution for stranded wire in a clamped connection is to install a bootlace ferrule over the loose strands.

@ElectromagneticVideos

Жыл бұрын

That's interesting - I have wondered about reliability. I have seen numerous wires in screw connections done with the end of the stranded wire being soldered. I wonder what the failure rates are and how long the cold flow you describe takes. I assume it depends partly on pressure and temperature during normal use?

@tsbrownie

Жыл бұрын

And solder the bootlace ferrule. 😉

Great video! I now need to check my cheap chinese variac to see if it's wired correctly...

@ElectromagneticVideos

Жыл бұрын

Thanks! Actually it would be very interesting to hear if yours was wired correctly - or for that matter from to hear from anyone else reading this!

Thanks for the video. I like watching you work.

@ElectromagneticVideos

Жыл бұрын

Well thank you!

Nice work, finding and fixing that factory fault. I knew something was wrong as soon as I saw the blue wire (neutral) going to the breaker (I hate switched neutrals with a passion - the wrong things end up live at the wrong time). I recently got a second hand 10 amp Superior Electric Powerstat(R) (another trade name for variable autotransformer, but never as catchy as Variac) model 3PN116B for free (apparently, the University of Rochester's Chemistry Department has outlawed these for heating control [understandable, I have seen more than one flask melted with a Variac controlled heating mantle], so a buddy of mine snagged a couple). Fortunately the only thing wrong with it was a missing cap on the fuse holder. I wasn't able to find a fuseholder with the same cap, so I just replaced the whole fuse holder, added a 10 amp fuse and it works fine. Superior Electric is still making Powerstats, although the current comparable model is 3PN116C (which sells for ~$770 at Newark: www.newark.com/superior-electric/3pn116c/variable-transformer-120v-10a/dp/32M1447?ICID=I-HP-STM7REC-RP-1 ). I find that Variacs are like clamps for woodworkers, you can never have too many. My daily driver is a 15 amp model that I bought bare about thirty years ago and put in a case with an RFI filter, magnetic circuit breaker, current and potential analog meters. I also have a very small, Staco brand, 2.25 amp (0.3 kVA) unit that was part of the first power supply I ever built (along with a 12 volt, 5 amp transformer, bridge rectifier, large electrolytic cap and pair of meters all from Radio Shack) about fifty years ago (still works fine). I have another Staco, bare 10 amp model (new in box) and three more used Variacs (120V/10A, 120V/20A and 240V/50A, for when I get that pole-pig) that all need some work.

@ElectromagneticVideos

Жыл бұрын

My problem is I can never remember the European color code for wires. But the just the green live output wire should have been a tip-off for me not to trust anything. Your were sure lucky getting that one. And your right - you cant have too many of them. I actually have an vintage General Radio 20A variac that I got when I was a student and a bunch of us went to a hamfest. Unfortunately Its brush is now worn and I have to order a replacement which will cost more than the cost of the Chinese variac, but the build quality of the vintage Made in USA one is so much better!

those chy knees multi recips are outlawed by code in MORE and more places, they started cropping up a few yrs back due to our friends at AMAZON

@ElectromagneticVideos

Жыл бұрын

Yeah - any regulation/restriction of their distribution has effectively evaporated.

I had a power strip with those multi-compatiblity outlets...it was used for a yearly Halloween party, and for light loads, it did fine...I wouldn't trust it with heavy loads, though..

@ElectromagneticVideos

Жыл бұрын

I sure learned not to trust them the hard way! I also actually have a power strip with them - got it at the Habitat ReStore - I looks real Chinese not made for export so I'm guessing from someone who lived there. I keep it just in case I need to test something with foreign plug.

Nice job!

@ElectromagneticVideos

Жыл бұрын

Well thank you! Lets hope it lasts a good long time after that amount of work!

For what it's worth I have one of these cheapie variacs, but mine is the 240V variant. The wiring etc was all done as poorly as yours, straight out of the box. It wouldn't surprise me at all if nothing had been fiddled with in yours even if the case had been opened previously.

@ElectromagneticVideos

Жыл бұрын

That's interesting! I really was wondering if others were done like that - you confirmed it! By the way - sorry for the delay in replying - for some reason some comments dont seem to show up till a while later. A bug in KZread perhaps!

13:54 at this point you can see that the ground crimp connector is not properly fasten down to the metal chassis, hope that you did fix that later. 15:50 to clean the gliding pad for the carbon brush, you can use normal print paper soaked in Isopropanol, this acts like a very mild sandpaper.

@ElectromagneticVideos

10 ай бұрын

Yes - did make sure the ground was good - that variac was so poorly made! Never heard of the "paper soaked in Isopropanol" trick - thanks pointing that out - I will remember that for future use. I do have a much nicer vintage General Radio Company variac that needs the brush replaced. When I do I will try your "paper soaked in Isopropanol" technique!

👍enjoy always.

@ElectromagneticVideos

Жыл бұрын

Thanks!

Color coding is weird because they are differentiating between line in and variable out. Also, that's a version of a standard Chinese two-prong with a US-style ground added. But, the Chint brand circuit breaker is actually a well-known and very good Chinese brand, so there's that...

@ElectromagneticVideos

Жыл бұрын

Good point - but I still dont like green for live out! Good to hear that the breaker is a good brand - I never really know with Chinese stuff - sadly the reputation of good quality Chinese stuff gets hurt by all the knock-offs.

@georgen.8027

Жыл бұрын

@@ElectromagneticVideos The irony with Chinese stuff is all the good quality "versions" are sold on the domestic market, which is now highly regulated, and the crap is exported since it doesn't have to meet the same safety standards (in theory the importer is responsible for ensure UL/CSA, but customs is busy with other things ;)

@georgen.8027

Жыл бұрын

@@ElectromagneticVideos Consider a regular power bar. On the Chinese market it has to meet CCC approval, meaning flame-retardant plastic, copper bus bars, conforming plug, Cu wire in the cord of the correct gauge and a breaker or fusible link. Export can be ABS, thin wire, "universal" plug which makes terrible contact and has been banned in China for 10 years, etc...

@georgen.8027

Жыл бұрын

@@ElectromagneticVideos Plus, the reviews on Taobao are fanatical. People take things apart, show the internals, weigh them, use calipers to check wire gauge is as advertised, etc. and these things are often sold in tremendous volume (100,000s) with thousands of reviews and a complaint mechanism which can get the factory in serious trouble if they are found to be selling non-conforming or misadvertised products. But they only care if it is sold in China.

@ElectromagneticVideos

Жыл бұрын

@@georgen.8027 Yes- funny - we know know good stuff is manufactured there. I didnt know it was regulated for domestic use there. I get a lot of emails at work from companies in China offering to be the interface to Chinese manufacturers to ensure the quality of the goods that is purchased. Not sure how reliable those intermediary companies are and I would guess large importers have their own QA offices in China.

This is making me concerned about the similar devices we have running at work, they have the same basic design but with a Schuko socket. I actually suspected an issue like this before when I had one arc upon inserting the plug, which probably has no protective earth...also I just know the person who got them just buys whatever is cheapest.

@ElectromagneticVideos

Жыл бұрын

Well mine did have a real earth on the socket. I was the melting that was the first problem and I did notice an arc once time due to the poor connection. Besides poor contacts from the universal socket, the plastic on the outlet was soft and clearly easily melted with heat - so maybe look at the Schuko socket on your units and see if its also softer plastic. Your advantage is generally lower currents due to the higher AC voltage so heat in the socket might be less of a problem. And since your plugs and equipment isnt polarized, the live-neutral flip should have less effect since it would depend on which way you plug the variac into the wall. Its really too bad that they seem to skimp on the plugs!

You really did all that extra work instead of switching the wires you put on?

I really like your videos! You could use a cheap lapel microphone instead of that big headset style one though.

@ElectromagneticVideos

Жыл бұрын

Thanks Alex! I actually originally used a lapel mic but I found the way I move my head around while doing stuff it was very hard to get a consistent audio level. This is the 4th mic I have tried and so far the best for my level of motion - it keeps the mic a consistent distance from my mouth. If you have any particular mic you would suggest I try please let me know - I would like a less obtrusive one .....

@HIDLad001

Жыл бұрын

@@ElectromagneticVideos The more that I think about it, a less intrusive wireless (not Bluetooth, because Bluetooth microphones stink) headset microphone would probably be a better choice than a lapel microphone.

@ElectromagneticVideos

Жыл бұрын

@@HIDLad001 Yeah - the real issue I find its is hard to get useful practical reviews of how good mics really are particularly for this sort of use. The one you see is a Shure PGA31-TQG Headset Microphone which actually is highly recommended for noisy stage use. Does require a Shure RK100P XLR adapter because Sure uses a proprietary connector. Amazingly the combination was only a bit over $100. It is very good at external noise rejection which is great for some outdoor videos.

@HIDLad001

Жыл бұрын

@@ElectromagneticVideos That is a good thing to have, but would it be possible to try to conceal the cable and maybe have the headset a little bit closer?

@ElectromagneticVideos

Жыл бұрын

@@HIDLad001 Yeah - I should take more care concealing the cable! I'll do that next time! If by closer you mean the mic closer to my face? I found that with it closer there was too much breathing noise getting through. I'll experiment a bit more!

striped green/yellow is ground on everything I have worked with.

@ElectromagneticVideos

Жыл бұрын

Over here (Canada/US) Ground is often Green unless it is European or Asian when its green/yellow as you describe. I tend to prefer that either green or green/yellow be limited to ground to avoid confusion which I guess is why I didn't like the green live output wire.

@liam3284

Жыл бұрын

Green for live is pretty weird. China should use red (active) blue (neutral) green/yellow (protective earth). In Aus/NZ it is red/black/ green+yellow for fixed wiring. Or brown/blue/green+yellow for cords.

I don't like these universal receptacles. Everything fits in there somehow, but nothing properly as it should! Here in Germany, these are also not approved, because the protective conductor does not get contact with these sockets.

@ElectromagneticVideos

Жыл бұрын

Agree - they are terrible. I was going to include showing how poorly the pins of North American and German plugs fit in the universal receptacle but the video was getting too long so there will be a follow up one. To your point - the German plug's pins seems to touch the out contacts of receptacle in one small area, and North American plug's blades touch the inner receptacle contact. Small surface area, minimal pressure between contacts - not a surprise it melted. And as you point out, not ground for the German plug. I would only use a receptacle like that for a shaver or cell phone charger so some similar tiny load.

i'd recomend replacing this circuit braker. i doubt you NEED 6000A to be honest... Get an EATON B25 or B16 or even C16 or C25... Much better quality and much more reasonable currnets For non europeans: B - Trips as soon as hits target current e.g B16 trips at 16A Immediately C - Trips after a specified period of time after hitting target currnet so C25 will allow like 35A and maybe then trip but will sustain 25+ A for some time.

@justin8894

Жыл бұрын

They make good turbochargers too.

@ElectromagneticVideos

Жыл бұрын

That's interesting to hear about the European designations. I'm not sure I trust the Chinese circuit breaker anyway - apparently a number of them are no more than switches - sadly short of actually testing or dissembling it, there is no way of knowing if its real or fake. A project for another day. Since the ariac is rated at 20A, for the sort term I will rely on the 15A or 20A breaker in the wall panel. Interestingly, the panel breaker (Eaton BR) tripped once when I was using the variac but the variac's breaker did not.

@liam3284

Жыл бұрын

The way it was wired, live had no protection, it was only switching neutral. I am surprised the input, rather than the output has protection, because, due to transformer action it is easy to overload the output while the input current appears fine.

@ElectromagneticVideos

Жыл бұрын

@@liam3284 You know, your right! At lower output voltages one could really overload the transformer windings. Ideally it would have two breakers, one on the input and one on the output.

That's the color scheme for country of origin

@ElectromagneticVideos

Жыл бұрын

The blue and brown - or do you mean the green that is not ground?

@Jason-fg4jr

Жыл бұрын

@@ElectromagneticVideos sarcasm seems like all the equipment I hook up that people get a good deal on the net the colors scheme is never right I have to always get my volt meter out... or risk a claim

@ElectromagneticVideos

Жыл бұрын

@@Jason-fg4jr Checking sure seem to be a goo idea. In fairness to the manufacturer of the variac, I bought it used so it is possible that the previous owner did something like changed the power cord and mixed up the live and neutral.

@Jason-fg4jr

Жыл бұрын

@@ElectromagneticVideos 👍🏼 stay safe enjoy what you share with us

@ElectromagneticVideos

Жыл бұрын

@@Jason-fg4jr Thanks!

Oh yeah.... those multiple compatibility outlets are VILE. They are good for small loads like a phone charger or laptop but definitely not good for sustained high current.... Dealt with them on cheap power strips while working in China. Most of the outlets melted from use of a small heater. Every now and then you see the same ones at flea markets in the States. Buyer be ware! I think I remember your saying that's a 20A output variac? Definitely poor choice on the manufacturer's part to use that outlet. That is amazingly awful how badly that variac was wired. I have purchased several of them from Fry's Electronics under their Philmore brand. (if I remember). Those have always had good outlets and been wired correctly, thankfully. The Chinese did a pretty good job copying the original Variac design in most cases it seems. I would expect the actual variable autotransformer part should work well for years now that you've got it rewired correctly.

@ElectromagneticVideos

Жыл бұрын

Yeah - terrible idea to have an outlet like that in a place intended for 20A. I'm not sure that it was miswired like that from the manufacturer - I bought it used and it could have been rewired by a previous owner but why someone would have done that is a mystery. Fry's! I went to a Fry's in Silicon Valley in California in the early 90s when it was a real tech place as opposed to a version of Best Buy. It was a great place. Yeah - it should work fine from now on. I do have a vintage General Radio variac which needs the brush changed - I'll get to it e- someday - it is much more solid construction as were most thing from way back!

@davida1hiwaaynet

Жыл бұрын

@@ElectromagneticVideos It would be ok if the Variac had multiple outlets and was used for several small loads at once, but that one outlet is going to have to do the whole capacity! I recently refurbished a vintage Powerstat one. I can't remember if I published that yet. Will share a link when I get back to my computer later.

@ElectromagneticVideos

Жыл бұрын

@@davida1hiwaaynet I'll look for your video! I'm going to do a follow up on that socket - was going to take a deeper look at in in this video but the video got too long because of the miswireing issue. I was going ta ask - what did you do in China? That must have been interesting!

I'm really confused as to why you would put a 20 amp outlet on something that's plugged into a 15 amp circuit

@ewicky

Жыл бұрын

So that he has the option to plug a 20A appliance in. For example, a resistive load on a Variac could be turned down so it runs at less than 15A. Kinda the point of a Variac...

@therealromster

Жыл бұрын

Also at lower voltages, the auto transformer can supply more current at less volts, although the winging thickness and thermal mass limits this to less than one would think.

@ElectromagneticVideos

Жыл бұрын

The two gentlemen who replied below answered with my thinking exactly. Also with pointing out that it is something that should only really be done on test equipment being operated by someone who understands what they are doing rather than a normal consumer (who is unlikely to be operating a variac anyway).

@liam3284

Жыл бұрын

consider, it can output 60 volts at 20 amps, while the input is 120 volts at 10 amps.