AC to DC converters in series?  - Page 1
Forum section: electronics / beginners

author: Renegade
author_rank: Regular Contributor
timestamp: March 01, 2016, 10:49:18 pm
content: While you can stick batteries in series to add voltages, can you add AC to DC converters in series to up the voltage?I have a few of these:http://www.aliexpress.com/item/AC-85-265V-DC-12-18V-Power-Supply-LED-Driver-for-4W-5W-LED-Light-Bulb/32451187923.htmlIt's a "AC 85 ~ 265V DC 12-18V Power Supply LED Driver for 4W 5W LED".To be clear, can I wire together the +/- DC outputs like you would do with batteries?

author: michaeliv
author_rank: Frequent Contributor
timestamp: March 01, 2016, 11:01:06 pm
content: Can't really tell from the listing if the power supply is fully isolated. Seems not to be.If it's not then you can certainly not stack them.

author: exe
author_rank: Unknown
timestamp: March 01, 2016, 11:10:44 pm
content: Quote from: michaeliv on March 01, 2016, 11:01:06 pmWhy do you think so? While I'm proposing to be on a safe side and not chain without 100% confidence, it looks like a flyback DC/DC converter or something. I can recognize the driver and the diode (https://en.wikipedia.org/wiki/Flyback_converter). The isolation is provided by the transformer.The best way to tell would be to reverse engineer the schematic.

author: michaeliv
author_rank: Frequent Contributor
timestamp: March 01, 2016, 11:21:29 pm
content: Seems very similar to the power supply in Mike's monster 60W LED bulb : youtube.com/watch?v=ZbBMSSr6BgkThat is not isolated

author: Renegade
author_rank: Regular Contributor
timestamp: March 01, 2016, 11:59:17 pm
content: Is there any kind of cheap hack that would allow me to test it to find out if it is fully isolated?I searched for a schematic, but couldn't find anything, and reversing this to figure out if it's fully isolate is currently beyond my depth.If they are NOT fully isolated, and I tried to chain them together, what would happen?

author: michaeliv
author_rank: Frequent Contributor
timestamp: March 02, 2016, 12:09:34 am
content: Quote from: Renegade on March 01, 2016, 11:59:17 pmBOOM!Quote from: Renegade on March 01, 2016, 11:59:17 pmTest the impedance between the AC input and the DC output.Also if the big cap that I see in the pics is rated at 400v it's very very likely the thing is not isolated.Also post the code on the IC and any other transistors/IC's you see.PS what are you trying to power with them chained together ?

author: Renegade
author_rank: Regular Contributor
timestamp: March 02, 2016, 12:38:38 am
content: Quote from: michaeliv on March 02, 2016, 12:09:34 amGuess I'm not trying that then.Or am I...?(/jk)Quote from: michaeliv on March 02, 2016, 12:09:34 amImpedance between the AC in and DC out is infinite (in all combinations).The caps are 400v and 4.7uF.ICS:1. AVM40B2. LB5M - 4B373. ES1D (I think this is a diode? It has a "D2" beside it on the board.)Quote from: michaeliv on March 02, 2016, 12:09:34 amI need 36V for some 100W LEDs:http://www.aliexpress.com/item/1Pcs-Full-100W-LED-Integrated-Chip-light-Source-IC-11000LM-High-Power-lamp-Beads-30-32V/32322492881.htmlVoltage: 30-36VForward Current: 3000 mAMy DIY benchtop power supply will only kick out 26~27V, so I need to boost that up to 36V with a booster that I have, but I'd like to try something else that I can put in an enclosure. These are some of what I have, and I was wondering if I could manage it.I have 8 of those LEDs, and would like to get them all powered up in an array. (Or as many as I can manage.)I know that's an insane amount of light. The answer to "why" is "because I'll learn something along the way".

author: bills
author_rank: Frequent Contributor
timestamp: March 02, 2016, 12:50:39 am
content: Try one of these, they will run a couple of 100w leds.http://www.amazon.com/GERI-Converter-10-60V-Voltage-Regulator/dp/B00VUCK78M/ref=sr_1_4?ie=UTF8&qid=1456879660&sr=8-4&keywords=60v+boost

author: michaeliv
author_rank: Frequent Contributor
timestamp: March 02, 2016, 01:03:58 am
content: Quote from: Renegade on March 02, 2016, 12:38:38 amWell those cheapo power supplies can only output 4W so you can't use them. Even 3 chained together will only output 12W, not even close to your required 100.

author: Renegade
author_rank: Regular Contributor
timestamp: March 02, 2016, 01:13:28 am
content: Quote from: bills on March 02, 2016, 12:50:39 amI've got a few DC/DC boosters, and was using one already. But thanks for that anyways.Quote from: michaeliv on March 02, 2016, 01:03:58 amI also wondered about that. Still, even if it won't work, I'm curious to know if I can manage to chain them as it may come in handy in another situation.From above, the impedance is infinite, so does that indicate that they are or are not fully isolated?

author: Zero999
author_rank: Super Contributor
timestamp: March 02, 2016, 08:50:25 am
content: One thing to bear in mind is that even if they're fully isolated, connecting multiple PSUs together will increase the leakage current via the Y capacitors, with could be a problem unless the power supplies are earthed.

author: Renegade
author_rank: Regular Contributor
timestamp: March 02, 2016, 01:14:51 pm
content: Quote from: Hero999 on March 02, 2016, 08:50:25 amThese tiny things aren't earthed, so I suppose I'll just give up on the idea. Thanks for the info.