Where to find a transformer? - Page 1
Forum section: electronics / beginners

author: PotatoBox
author_rank: Regular Contributor
timestamp: October 30, 2016, 05:13:24 am
content: Which devices can I salvage a transformer for a linear power supply?

author: singapol
author_rank: Frequent Contributor
timestamp: October 30, 2016, 05:22:08 am
content: The best place is from consumer electronics like VCD players,audio equipment like the older generation of products as now most have switchmode power supplies in them.PS if yopu want big ones then from audio power amplifiers or home theater amps say 50W and up.

author: PotatoBox
author_rank: Regular Contributor
timestamp: October 30, 2016, 05:56:34 am
content: Quote from: singapol on October 30, 2016, 05:22:08 amWhat era would I look for for old AV equipment?

author: Seekonk
author_rank: Super Contributor
timestamp: October 30, 2016, 06:23:50 am
content: There is a shop I do repair work for that has a HVAC division. I have stacks of 24V 45W control transformers that have taps for 120, 208,,230,265 and 480V Putting a couple in parallel or series gives you a lot of options. These units were just going to scrap.

author: PotatoBox
author_rank: Regular Contributor
timestamp: October 30, 2016, 03:32:02 pm
content: Would a VCR have one?

author: singapol
author_rank: Frequent Contributor
timestamp: October 30, 2016, 04:11:35 pm
content: Quote from: PotatoBox on October 30, 2016, 03:32:02 pmVCR? Most likely switchmode. How about old computer broadband modems external power supply but normally about 1 amp. Old computer speaker systems. Best bet is still audio amps from 70s -2000?

author: PotatoBox
author_rank: Regular Contributor
timestamp: October 30, 2016, 04:40:46 pm
content: Quote from: singapol on October 30, 2016, 04:11:35 pmI'll look into some old hi fi equipment. Would a cheapo audio reciever from the mid to late 90s maybe have one?

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 30, 2016, 04:44:01 pm
content: Most consumer stuff after 2000 would be questionable.You can often tell by "heft". Gadgets with "heavy iron" transformers will simply weight more.

author: PotatoBox
author_rank: Regular Contributor
timestamp: October 30, 2016, 05:53:54 pm
content: Would there be a way to find one with a transformer without opening the device?

author: NottheDan
author_rank: Frequent Contributor
timestamp: October 30, 2016, 06:10:33 pm
content: Quote from: PotatoBox on October 30, 2016, 05:53:54 pmLook through the vent holes.

author: dekra54
author_rank: Unknown
timestamp: October 30, 2016, 07:12:27 pm
content: I would go for and old maybe broken PA-Amplifier from ebay. It's unlikely that the transformer is damaged and you have it already in a nice enclosure with massive heatsinks and a +/- output . If youre lucky you can even use some of the output transistors.Edit: But look for a datasheet... if the amp is heavy (from about 10kg up) it's with 99% chance a transformer inside. Because even if it's old it can have a smps.

author: DimitriP
author_rank: Super Contributor
timestamp: October 30, 2016, 07:34:42 pm
content: Quote from: PotatoBox on October 30, 2016, 05:53:54 pmJesus!.Pick it up. If the weight is evenly distributed, no hefty transformer inside, or just a puny one.

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: October 30, 2016, 10:22:12 pm
content: Not surprisingly, a good place to find such transformer is in linear power supplies.If you can access to a university with physics labs, they have probably many linear power supplies that they are getting rid of , specially the ones that could have been devised to produce -15V + 15V power supplies for experiments.Eventually, you can also get a full laboratory power supply.Another source could be old UPS. People have tendency to dump them when the battery is no longer working. Many of them have nice transformer.

author: TheAdmiralty
author_rank: Contributor
timestamp: October 31, 2016, 05:33:59 am
content: Look for old commercial audio systems. I scrapped the intercom driver system out of an old supermarket, and the thing had about twenty pounds of transformers in it. Anything up until the late 80s is a pretty good shot, and even in terms of recent hardware a lot of these audio systems will run on linear supplies for better signal-to-noise performance. Give it the heft test and you'll know when you've found an iron-core transformer as one side of the things will be about twice as heavy as the other. Good source of heatsinks and other good stuff too, as a lot of them have grossly inefficient amplifier sections that need to drive alotof power.Edit:I didn't even realize it, but dekra said the exact same thing I just did. Looks like I'll repeat it, though, because these things really are great salvage sources.Also microwaves, although I takenoresponsibility for what you do to yourself with one of these.Old(!) CRT monitors will probably have a transformer or two in there, though one of them is likely going to be massively high voltage and so is probably not of much use to you. I tore down a Tandy EGA display that actually had a small linear supply. Again, I take no responsibility for what you do to yourself with this, either.

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 31, 2016, 11:30:13 am
content: There is a whole sub-culture of people who re-wind microwave oven transformers ("MOT"). Virtually nobody has a project that can use a MOT without extensive re-work. Typically removing the thousands of turns of high-voltage secondary. One of the most popular uses is to put one or two turns of battery cable through the MOT and use it for spot welding. Else, if you aren't into transformer winding, an MOT isn't very practical. Which is unfortunate considering how many are available. I got over 8000 hits on YouTube for: MOT rewindIME, CRT monitors (or TV receivers) are one of the least likely to have traditional linear power transformers. Except for some old-school broadcast gear. Or truly antique TV sets from the 1950s. Manufacturers early on learned how to design TV receivers with no power transformer at all ("hot-chassis").And transformers from tube gear (microwave ovens, TV or radio receivers, etc.) are designed for high voltages and low currents. Not very useful for solid state (low voltage, high current) circuits.

author: senso
author_rank: Frequent Contributor
timestamp: October 31, 2016, 05:14:48 pm
content: If you want to start small a 50VA transformer brand new is cheap, place an order at Mouser or Digikey and add one to the rest of the components, you might spend 15-20$ to get a suitable transformer..

author: Seekonk
author_rank: Super Contributor
timestamp: November 01, 2016, 06:07:47 pm
content: I just got another four 45VA transformers from the HVAC guys today. Could have had another dozen, but they had already fork lifted them onto the scrap truck. They are coming out of my ying yang. Wish I had a use for them, just hate to just let them go for scrap. These HVAC guys are a gold mine.

author: PotatoBox
author_rank: Regular Contributor
timestamp: November 05, 2016, 04:02:06 am
content: Would wall warts have them? I know that the older ones had them. Should I look for chunky ones and assume that it has a transformer?I went to a thrift store today to see if I could find any devices regarding to transformers and thought about the wallwarts. Many of them "Plug in class 2 transformer" on them, which sounds like it would a be a linear transformer.

author: mtdoc
author_rank: Super Contributor
timestamp: November 05, 2016, 04:22:49 am
content: Quote from: PotatoBox on November 05, 2016, 04:02:06 amYes, the big, heavy wall warts have them. My local GoodWill (thrift) store usually has several - generally from older gear.