AC power testing adapter idea - Page 1
Forum section: electronics / beginners

author: Frankentronics
author_rank: Regular Contributor
timestamp: January 09, 2018, 06:52:39 pm
content: Greetings,As a beginner I don't know how much I can contribute to this forum, but perhaps I came up with an idea that some people here can find useful.Basically, after I put together my own "Variac" I figured out that I didn't really have a practical (and safe) way to plug power chords into the Variac's receptacle, as many of those chords were just stripped wires. So, I went through my salvage bins and put together an adapter, that consists of an emptied shell from a wall wart and a set of speaker connectors.It is all self explanatory from the images.I find this to be very useful and versatile, as I can unplug it from my Variac and plug it into any receptacle. Or even put it into my pocket and take it to a friend's house, if I want to do any work there.Hope some of you find this idea useful.Regards...

author: ovnr
author_rank: Frequent Contributor
timestamp: January 09, 2018, 06:56:15 pm
content: Or you can buy one ofthese, which are safer and actually built for mains stuff. Just a shame they're so shockingly expensive.

author: james_s
author_rank: Super Contributor
timestamp: January 09, 2018, 10:10:52 pm
content: Cord, a chord is a combination of musical notes.Be careful using adapters like that, those terminals are not designed for line voltage and may not handle much current. That said, for years I've used cords with a plug on one end and alligator clips on the other for purposes like this, potentially dangerous but certainly handy.Those Quicktest adapters are great but about twice they price they ought to be IMO. That said it's a niche device with a small market, and they seem to have never got much if any traction outside the UK. Wasn't until Youtube that I'd ever heard of one.

author: Frankentronics
author_rank: Regular Contributor
timestamp: January 09, 2018, 11:09:22 pm
content: Quote from: james_s on January 09, 2018, 10:10:52 pmWoops! Still learning English. Thanks!Quote from: james_s on January 09, 2018, 10:10:52 pmI was wondering about current, actually. If there was a fuse inside the adapter would that do the trick? Just intuitively the fuse feels like a cat whisker, much thinner than the connections on the speaker terminals. It "feels" to me that the fuse would blow before there was any arching or melting going on at the speaker terminals. But I'm not experienced. I might be wrong.

author: james_s
author_rank: Super Contributor
timestamp: January 09, 2018, 11:31:01 pm
content: A fuse might help, best approach I think is to make sure a test rig like that is never left powered unattended and it should be clearly labeled that it is a test device for temporary use and dangerous voltages are present on the terminals. This will depend on your household of course, you don't want someone who doesn't know plugging it in thinking it's something else.

author: jeroen79
author_rank: Frequent Contributor
timestamp: January 09, 2018, 11:45:00 pm
content: If you want to know if it is safe then you should look for a datasheet.That would specify the maximum current and voltage.Try looking around on mouser/reichlt/farnell/conrad/whatever for a similar connector.They usually will have a datasheet with it.

author: PTR_1275
author_rank: Frequent Contributor
timestamp: January 10, 2018, 12:15:20 am
content: I have numerous test leads around the workshop for various ac testing.The leads that have bare wires or alligator clips on them are hanging up away from all the other IEC type leads, then when not in use the exposed wires are taped to the mains plug in such a way that you can’t plug it in without realizing it’s a dead mans plug. As soon as I finish using them, no matter how busy or critics other jobs are, it gets taped and put away.I also have one of the cliff testing boxes. If I didn’t watch big Clive, I’d never known about them. Yes they’re a bit pricey, but for a bit of a niche product that hasn’t saved me more time than it cost, it was worth it to me (and it’s safe)With the adaptor box you made up, it will work, just be careful when using it. The voltage shouldn’t be a problem but the current couldake things get messy quickly. Those connectors heat up, then the plastic melts and the spring pushes the plate through the plastic. Putting a fuse in there is a good idea, but I’m also not sure what you work with or are planning to use it for.I would also make sure it’s out of reach of anyone else when you’re not around so someone doesn’t pick it up and plug it in without knowing what it is (as others have mentioned, warnings or something similar on it)

author: Frankentronics
author_rank: Regular Contributor
timestamp: January 10, 2018, 04:57:03 pm
content: OK, you all make good points.I think I'll put together an upgrade with a fuse. I'm guessing a 1A fuse should be OK, right?What I plan to use this for, mostly, is to test salvaged transformers. I am planning to learn about building audio amps and power supplies for such amps.This adapter would only be used to quickly weed through a bunch of salvaged transformers, so I can select the one I wish to use for the project. Once I know which transformer I want I would make a proper AC connection and work further from there.Is there perhaps a better way to plug transformers to my Variac? When I built the Variac I started plugging the ends of stripped power cords into the Variac receptacle and that looked dangerous. I also user alligator clips, but that looked dangerous, too, because there's always a tip of the alligator clips that remains exposed beyond the sleeve and things tend to move on an active workbench. And of course, it takes too much time to build a proper connector for each transformer I want to test.But perhaps there are other economical ways of doing that.Thanks...

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: January 10, 2018, 06:40:08 pm
content: I am sorry to tell you that, but do not like very much your adaptor.I am concerned by the fact that some wire could be loose and you would get shocked while plugging or unplugging.I suggest that you take a standard power cord, with a normal plug that you plug in your variac. On the other hand, you puta box with your adaptors for attaching bare wires. And if possible, with a fuse.For my own use, I have a power cord where one side are attached Wago 3 wires connectorswhere I can attached bare wires.Wago are rated for 400V, (peak 4KV), 32AI can plug this cord in the variac, or in a plug with 2 or 10 A and 30mA differential breaker, which I also use as a switch.

author: piguy101
author_rank: Regular Contributor
timestamp: January 11, 2018, 12:29:15 am
content: Nice adapter! I'm still looking for something with a male mains connector and female banana jacks (preferably the kind that accept shrouded banana jacks) to use on a variac. I may end up making my own if I can't find anything.

author: stj
author_rank: Super Contributor
timestamp: January 11, 2018, 01:39:35 am
content: Quote from: ovnr on January 09, 2018, 06:56:15 pmlook harder.http://cpc.farnell.com/unbranded/tb1/test-block/dp/PL15699

author: Bratster
author_rank: Frequent Contributor
timestamp: January 11, 2018, 03:30:48 am
content: Quote from: stj on January 11, 2018, 01:39:35 amIf only I could get one in the USA near that price....Right now I use a "suicide cord" with Wago connectors on the end.Sent from my Nexus 6 using Tapatalk

author: Frankentronics
author_rank: Regular Contributor
timestamp: January 11, 2018, 05:16:48 am
content: Quote from: JacquesBBB on January 10, 2018, 06:40:08 pmOh, no need to be sorry. This is why there are forums and I do want any constructive feedback.I didn't even know about the existence of these Wago connectors. I'll look into this and possibly use one to make a better jig. The only thing that doesn't look too good on this Wago connector is how closely spaced the holes are. It just feels to me that there could be a short connection, inside, if braided wires are used.Quote from: stj on January 11, 2018, 01:39:35 amI do like this, though, for a good price. Thanks for posting this.

author: SeanB
author_rank: Super Contributor
timestamp: January 11, 2018, 08:04:01 am
content: One Wago connection per wire, those are meant to join 3 wires ( or 2) in a junction box, and are pretty good at it. For your test lead you just have one per lead, so one line, one neutral and one for ground.

author: Frankentronics
author_rank: Regular Contributor
timestamp: January 11, 2018, 03:54:10 pm
content: Quote from: SeanB on January 11, 2018, 08:04:01 amOh I see. So that's not the best solution.However, after some more Googling I did find another connector.https://www.banggood.com/3-Pins-Quick-Fix-Push-in-Clip-Spring-Connector-Cable-Terminal-Block-for-3528-5050-LED-Strip-p-1162333.html?rmmds=cart_middle_products&cur_warehouse=CNThere are no listed ratings and it is designed for 12V LED strips. But I wonder if it would be better than my initial speaker connector idea, with a fuse, of course. Although it wasn't designed for mains I don't see how it would start melting if there was a fuse.

author: stj
author_rank: Super Contributor
timestamp: January 11, 2018, 05:31:25 pm
content: well.these say 10A but BG says dont go over 1500w which at 240v is 6Ahttps://www.banggood.com/20pcs-3p-CH3-Quick-Connector-cable-clamp-Terminal-Block-Spring-Connector-wire-without-welding-screws-p-1001559.htmlthese say 32Ahttps://www.banggood.com/Excellway-ET25-235-Pins-Spring-Terminal-Block-Electric-Cable-Wire-Connectors-5Pcs-p-1129219.htmlhttps://www.banggood.com/5Pcs-235-Pins-Reusable-Spring-Lever-Terminal-Block-Electric-Cable-Wire-Connector-p-1103030.html

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: January 11, 2018, 06:26:40 pm
content: Quote from: Adinol on January 11, 2018, 03:54:10 pmYes, with the Wago, you need one per wire.I know the above connectors. I bought some of them. They are supposedly designed for 250 V , but of very low quality. I would use them only for low voltage,and not for main.I feel that the Wago solution is much safer. I would fear to make the main wire loose, while attaching something.Of course, one should only do that after shutting down the main, but if you have double security, it is better.