Free: Transformers - from vintage test equipment? [SOLD] - Page 1
Forum section: electronics / general

author: sean0118
author_rank: Frequent Contributor
timestamp: January 12, 2022, 10:03:00 am
content: Hey, does anyone want these old transformers? Anyone can have them for free, but I'll give preference to anyone who can show a need for them.I've never tested them and wouldn't assume they are safe without an isolation test.I'm also not sure what they are from, maybe old test equipment? Anyone recognise them?I can post them (from Sydney, Australia) but it will be expensive...

author: jonpaul
author_rank: Super Contributor
timestamp: January 12, 2022, 10:53:22 am
content: shipping will be 100X the value.Use for paperweights, offer at a flea market or CL.Jon

author: Brumby
author_rank: Unknown
timestamp: January 12, 2022, 11:11:57 am
content: You just made me mentally review my collection of transformers.I don't think I'm game to do an actual physical check....Yeah - I don't need any more ... ... ...at the moment

author: alm
author_rank: Super Contributor
timestamp: January 12, 2022, 11:30:34 am
content: If this is a custom transformer for a specific piece of gear that someone is trying to repair, then that could have a substantial value, but only to that specific person and assuming you can find out what equipment the transformer came from. Otherwise, unless someone sees these pictures and recognizes a transformer, they will have very little value. Why would you use this transformer in a project instead of one you buy brand new?

author: sean0118
author_rank: Frequent Contributor
timestamp: January 12, 2022, 11:37:12 am
content: Quote from: alm on January 12, 2022, 11:30:34 amI know, that's why I made this thread... otherwise they are going in the ewaste

author: cdev
author_rank: Super Contributor
timestamp: January 12, 2022, 04:51:31 pm
content: The third transformer in the first pic may be fluid filledThey "oil" inside some may contain PCBsseehttps://19january2017snapshot.epa.gov/www3/region9/pcbs/faq.htmlOtherwise (well marked) transformers are super useful to have sometimes.These appear to have been labeled in order to keep their value and so they don't become junk by a thoughtful, electronics literate person.One appears to have fairly high current.I don't know. Right now I have space for stuff like that. I hate it when I throw away something and turn out to need it.In a pinch an old transformer combined with a bridge rectifier and capacitor can be useful.Its the most expensive component of a power supply and fairly easy to figure out the turns ratios of.(I use my feeltech siggen and multimeter for that, at low voltage, not lines voltage)

author: sean0118
author_rank: Frequent Contributor
timestamp: January 13, 2022, 08:21:53 am
content: Quote from: cdev on January 12, 2022, 04:51:31 pmThanks, that's a good point and I was concerned about the same thing when I first saw it. I don't think it's oil filled, but I guess there's a chance it was emptied or leaked out before I got it. So maybe I should dispose of it assuming is contains PCB. I can't see any plug on it, I'm not sure how it would have been filled?I think it might just be some type of radiation shield for sensitive RF applications etc, there's a similar one in this Bel white paper about EMC:https://belfuse.com/resources/whitepaper/signaltransformer/wp-ST-Controlling-EMI-in-Power-Transformers.pdfI'm not sure though, so maybe I should dispose of it properly. There's not much information available regarding small transformers with PCBs, although I assume they were produced.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 13, 2022, 06:57:17 pm
content: I think those are usually tar/pitch filled, but could possibly be anything, true.Tim

author: sean0118
author_rank: Frequent Contributor
timestamp: January 14, 2022, 12:22:57 pm
content: Quote from: T3sl4co1l on January 13, 2022, 06:57:17 pmThanks that's interesting, I can't find much information on this style. Is the tar to increase the isolation?I guess even tar could contain PCBs, I read online even some old building materials like caulking can contain them in high quantities. That's something i didn't know.Also I guess I'm getting off topic, but it seems both Freed and Paeco (made for HP) produced similar style transformers. I can't see any manufacturer logo on this one, but maybe it has been re-painted...edit: I won't throw these out just yet, I'm sure the moment I do someone will identify them as important

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 14, 2022, 04:28:25 pm
content: I'd be more worried about the creosote / coal tar-adjacent chemicals in there. Depending on which kind/source of tar it is exactly. Some kinds of half-decomposed hydrocarbons, in any case. Not volatile -- not a problem if you open it up. Have good ventilation if it starts vaporizing, y'know, that sort of thing.The seam is soldered if I'm not mistaken, so you'd need quite a large iron and a lot of bending to free it, or an induction heater. The latter might not actually be too unreasonable, as a bench-powered one could do (it probably only needs a low hundreds of watts), and control doesn't need to be anything special, just a signal generator and inverter, and a little care, would do the job. Resonant capacitors can probably be salvaged, etc.Mind, Iwouldbe the kind of person to breadboard induction heaters on a whim. Sure, it's not too hard when you know what you're doing, but getting there is another matter... so, I digress.And not like you want to open it, just FYI in case you're curious. The old "tub" capacitors are made the same way (but, they probably did use PCBs, beware!), and a lot of avionics are packed hermetically I think, and this is the standard method for servicing them.Anyways, if nothing else, those ratings look good for tube amp stuff? Maybe share on some related groups...Tim

author: cdev
author_rank: Super Contributor
timestamp: January 15, 2022, 12:58:12 am
content: Nice that somebody put so much work into marking them, I thought. That alone makes them potentially much more useful.

author: sean0118
author_rank: Frequent Contributor
timestamp: January 18, 2022, 11:39:54 pm
content: Transformers have found a new home