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        DIY 200A speed controller kit

#1 procrastination inc Sep 23, 2001 02:21 AM

DIY 200A speed controller kit
 
Wadaya reckon?

200A R/C MODEL SPEED CONTROLLER KIT: This kit is designed to work direct from a standard 1-2ms pulse from a radio control receiver to control an electric motor in one direction only. Features include a brake. Kit includes PCB and all on-board components including 5 high power mosfets and a small (26 x 64 x 38mm) case.

PUBLISHED: Silicon Chip Magazine

KIT PRICE: (K152) $35 (AUD)

Pic here:

http://www.oatleyelectronics.com/kits/k152.html

#2 steve lewin Sep 23, 2001 03:16 AM

For 200A read somewhere around 25-30A if you're lucky. I suspect the rating is based on the maximum MOSFET rating (like many car controllers). These in turn are based on the MOSFET being on a large force-cooled heatsink and kept to a temp of 25C. These have no heatsinks :(.

I guess you could put 200A through it for about 1/100th of a second before the smoke comes out. The real giveaway is the size of the wires in the picture. Can you imagine 200A through those weedy wires ?

Steve

#3 procrastination inc Sep 24, 2001 07:03 AM

Thanks.

so 25-30A is OK for an s600.

Is $18(US) too much for a big heavy 25A DIY speed control with no BEC?

#4 steve lewin Sep 24, 2001 01:00 PM

The price is not bad, the MOSFETs could easily cost close to that at retail prices. If you like electronic kits (plenty of fairly fiddly soldering) and want to to give a try it why not just go for it ?

You could test it to see how much current it will actually stand or you could tell us exactly what type the MOSFETs turn out to be and someone could probably give you a good idea of what it will do. I'd guess it would easily handle the average S600.

Have you read the article it references ? That probably contains some more realistic details.

Steve

#5 procrastination inc Sep 25, 2001 02:49 AM

>>Have you read the article it references ? That probably contains some more realistic details. <<


I looked for it on the web, no show. I'll have to see if the library has that back issue.

#6 MrBungle Sep 25, 2001 11:17 AM

This kit is marketed by Oatley Electronics as a 200A controller, but Silicon Chip ran the article as a 50A continuous controller(tested):



Silicon Chip - May 2000 - "50A Model Motor Speed Controller - With Brakes", Page 78

50A continuous rating, 1 x MPT2955 (Brake) + 5 x IRFZ44 (Power)

Voltage drop at 50A = 0.28v (worked using IRFZ44 datasheet, SC magazine claims 0.24v)

At 50A this controller has to dissipate approx. 14 Watts of heat, quite a lot without heatsinks.

#7 Trizza Sep 26, 2001 01:50 AM

Sounds pretty good, that ought to be plenty even for hot buggy motors right?
Could always add a small heatsink or some bent up aluminium. Stick the metal ends of the transistors out into the airflow.

#8 steve lewin Sep 26, 2001 04:25 AM

That sounds pretty reasonable. I'm not sure about 50A continuous unless the FETs are in a really good airflow. I usually think of IRFZ44s as safe at about 8A with no heatsink but I've never really tested them to destruction :)

However it should certainly take anything you could comfortably use with a 540/550/600 size motor. Why not try it and let us know how you get on ?

Steve

#9 MrBungle Sep 26, 2001 11:40 AM

procrastination inc,

If you would like to read up some more on this controller before purchasing the kit, send me an email with your address and I will send you a photocopy of the construction article from SC mag.
I would scan it and send via email, but I dont have a scanner :(


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