ebay PWM speed controller - 60 amps for less than GBP 10 ! - Page 1
Forum section: electronics / general

author: bigsky
author_rank: Regular Contributor
timestamp: July 27, 2017, 11:32:38 am
content: Apologies if anyone has spotted this one before:http://www.ebay.co.uk/itm/60A-DC-Motor-Speed-Control-PWM-Controller-12V-24V-48V-3000W-Adjust-PWM-Switch-HT/391827240622The mind boggles.1. Are those pcb terminals good for 60A ?2. Are the pcb tracks good for 60A ?3. Is the heatsinking adequate ? (12 heatsinks in close proximity!)4. Is the on resistance of the mosfets matched ? (assuming this matters - I think they have a negative temp coef so may self-balance to a certain extent, but 12 in parallel is rather a lot)If it does work OK, GBP 9.32 delivered is amazingly cheap for a 60A / 50V rated controller/

author: bigsky
author_rank: Regular Contributor
timestamp: July 27, 2017, 11:44:05 am
content: I just found some similar terminals to the ones on this board, and they were rated at 15A. I wonder how hot they get if you put 60A through them?And, of course, the electrician's rule of thumb is 16mm wire for 60A. You might get away with 10mm, but even so, getting it onto those terminals would be an interesting exercise.The joys of Chinese design!

author: wraper
author_rank: Unknown
timestamp: July 27, 2017, 12:39:08 pm
content: Dunno about 2 smaller electrolytic caps but 4 larger ones are counterfeit nippon chemi-con. chemi-con does not make capacitors with X style vent.

author: Urs42
author_rank: Unknown
timestamp: July 27, 2017, 12:53:13 pm
content: 60 China amps are about 6 normal amps.I got a "250w" 12V PWM motor controller from china, it did survive for about 20 seconds with a 250w load...

author: bigsky
author_rank: Regular Contributor
timestamp: July 27, 2017, 01:49:16 pm
content: I'm half-tempted to buy one and try it out, but what could I use as a suitable load? I could power it from a car battery as I don't have a suitable PSU, but the load side is more tricky. Buying some suitable high-power wirewound resistors will cost me more than the board itself!It looks like a good candidate for EEV Smoke.On a more serious note, the use of a stereo pot is rather curious. Perhaps one side is being used to feed a comparator to give an on/off, and the other side goes to the PWM driver.

author: Richard Crowley
author_rank: Super Contributor
timestamp: July 27, 2017, 01:52:50 pm
content: Quote from: bigsky on July 27, 2017, 01:49:16 pmIt seems possible that is an on/off switch an not a second pot on the back of that gadget. Hard to tell from the photo.Maybe we should tell the guy over at the "Electric Go-kart motor controller circuit" thread.

author: bigsky
author_rank: Regular Contributor
timestamp: July 27, 2017, 01:59:13 pm
content: Yes, I think you are right. It does only have two wires coming from it. Never seen one like that before - all the switched pots I've encountered have a plastic lump on the back for the switch, invariably mains rated. You learn something new every day.

author: schmitt trigger
author_rank: Super Contributor
timestamp: July 27, 2017, 03:09:27 pm
content: If you do decide to purchase one, and then -gulp- actually apply the full load, by all means take a video when you do so.We love exploding electronics videos!

author: Ampera
author_rank: Super Contributor
timestamp: July 27, 2017, 07:50:45 pm
content: I find this amusing.

author: Gromitt
author_rank: Regular Contributor
timestamp: July 27, 2017, 08:34:19 pm
content: Quote from: TwoOfFive on July 27, 2017, 07:50:45 pmWhy?

author: Ampera
author_rank: Super Contributor
timestamp: July 27, 2017, 09:58:57 pm
content: Quote from: Gromitt on July 27, 2017, 08:34:19 pmThis is:

author: Gromitt
author_rank: Regular Contributor
timestamp: July 27, 2017, 10:02:46 pm
content: Quote from: TwoOfFive on July 27, 2017, 09:58:57 pmAnd under that it says 'Exkludes:'

author: bigsky
author_rank: Regular Contributor
timestamp: July 27, 2017, 10:34:00 pm
content: Here's the same thing from a seller than ships to the US. USD 12.57 delivered.http://www.ebay.com/itm/DC-10V-50V-60A-Motor-Speed-Control-PWM-HHO-RC-Controller-3000W-MAX-Hot-Sell-/112396374984

author: TerraHertz
author_rank: Super Contributor
timestamp: July 27, 2017, 10:46:04 pm
content: I like how the heatsinks obviously have no mounting other than the transistor tabs, no insulation from the tabs, are pressed hard against the PCB, and there are tracks running under them with no insulation but the resist layer.

author: bigsky
author_rank: Regular Contributor
timestamp: July 27, 2017, 10:49:22 pm
content: Quote from: schmitt trigger on July 27, 2017, 03:09:27 pmI love exploding electronics providing it's not near me. I was once repairing a valve amp (not mine I hasten to add) and a cap exploded and shot the can across the room, narrowly missing my face.But finding a 3kW 48V PSU and load is beyond me, I'm afraid.

author: bigsky
author_rank: Regular Contributor
timestamp: July 27, 2017, 10:53:17 pm
content: Quote from: TerraHertz on July 27, 2017, 10:46:04 pmIf you look at the solder side picture, it looks like there is a single mounting post for each heatsink, which explains why they're rather crooked.

author: tszaboo
author_rank: Super Contributor
timestamp: July 27, 2017, 11:06:59 pm
content: The PCB tracks and terminals will not handle 60 A in still air. A 25 mm trace at 60A has 200K temperature rise, above ambient, and this devide 80mm total width into a H bridge.From that point, its just a question of the airflow.About the FETs... Actually it is not that hard to get 60+A fets in TO220, of course you need to keep it cool.This is my favourite:"Due to personal measurement technique is different, there may be 1-3 mm error of the physical.Thank you!"So apparently, length depends on your personal technique.

author: Ampera
author_rank: Super Contributor
timestamp: July 28, 2017, 05:14:50 am
content: Quote from: Gromitt on July 27, 2017, 10:02:46 pmI find it amusing that is says it ships worldwide, except for most parts of the world.

author: Red Squirrel
author_rank: Super Contributor
timestamp: July 28, 2017, 06:20:09 am
content: Wow might be worth getting just for the parts. Could probably build a half decent PSU with those fets.I also kinda want to see 60 amps going through there.

author: wraper
author_rank: Unknown
timestamp: July 28, 2017, 06:42:41 am
content: Quote from: Red Squirrel on July 28, 2017, 06:20:09 amYou are joking, right? At such price you can buy FETs with similar ratings from reliable supplier and what you actually need. Not likely counterfeits as electrolytic caps on the PCB.

author: djococaud
author_rank: Regular Contributor
timestamp: July 28, 2017, 07:24:37 am
content: Watch test videos on youtube !

author: jasonbay13
author_rank: Contributor
timestamp: August 07, 2017, 02:05:09 pm
content: I bought one of these (in the US) off ebay and it worked with my 24v bench supply for a few seconds just to test operation. hooked it up to my motor and battery pack of 33v, a few seconds later it wanted to go running full speed and shorted one of the mosfets. Yay. Same thing happened with a more expensive one i got from amazon, though it lasted a good deal longer. this was used with one of those little 250-350W razor bike motors.I have asked a question on EE.SE. I've googled many hours on this with absolutely no results matching my problems.https://electronics.stackexchange.com/questions/322644/48v-10-50v-60a-motor-speed-controller-pwm-shorting-and-running-full-speed#322644If anyone has any ideas I'd be happy if you would sharebut for the hour that it worked it worked well, didn't get hot or anything.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: August 08, 2017, 09:52:53 am
content: Well, I've heard it said that our products don't sell too well in China.Chinese buyer, "Only15A rating? I guess that means 1.5A then. Useless. Western products are so underpowered compared to ours..."

author: b_force
author_rank: Super Contributor
timestamp: August 08, 2017, 11:03:26 am
content: Quote from: Urs42 on July 27, 2017, 12:53:13 pmTo be very honest, it's nothing different than western marketing.They only don't sugar coat it (well, they do, but on a very different way).Most (audio) amplifiers for example (even from well known brands) can't deliver the power they are 'rated' for.I think Chinese selling marketing is very funny, it's blunt and overly positive.It's just copying western marketing in its purest form.

author: jasonbay13
author_rank: Contributor
timestamp: August 08, 2017, 12:40:57 pm
content: Very true, chinese always market it as 10x better than it is. But even still it shouldn't short out from just being powered.Is there anything i can buy for under 50usd to make this thing work? I've looked all around and the only thing i can find is one for 100USD made in Australia and those chinese 100A reversible controllers which i assume would have the same problem. they sell for 20-50.do you think the design is bad or just the mosfets being incapable? What if I were to replace them with:http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=235208367&uq=636377182888244470and to answer the original topic question, i'd say 60A is absolute maximum peak current and is unable to sustain for long. based off my short experience between two different boards.

author: schmitt trigger
author_rank: Super Contributor
timestamp: August 09, 2017, 04:47:30 pm
content: Quote from: TwoOfFive on July 27, 2017, 09:58:57 pmHmmmmmmmmmmmm..........they can't ship to Vatican City, but they do ship to Italy.Thus, if they want to use one of these for the Sistine Chapel, they will have to ship it to one of the many trattorias or gelaterias just outside of St Peter's Square.