Cheap Drive ESC

[duff]

Hobbyking sell the F20A which has some code knocking about that will convert it into a brushed controller with instant reverse. They are also under a fiver. Trouble is it has the same mixing issue that some of the botbitz controllers have.

[Rapidrory]

Couldn't find the F20A; this is the only other one I could see on HK.. http://www.hobbyking.com/hobbyking/s...=brushed%20esc. Seems alright, though it is only 2 cell. Also depends if it has full speed reverse...

[duff]

I think I missed a dash. It's the f-20a. Here's the link.

http://www.hobbyking.com/hobbyking/s...dProduct=15202

If you look in the files section at the bottom of the page there is a guide on how to make it into a reversible brushed controller.

[knightrous]

The F20A was the 25A ESC that BotBitz use to sell before it was replaced by the 30A ESC's.
The reason we abandoned the 25A ESC was the production quality changed dramatically and the controllers became rather unreliable.

[Rapidrory]

Ok, so bought some of the 20A ones off ebay to run my featherweight, and they worked fine...

... after replacing the microcontroller with firmware that worked, upgrading (adding) the noise protection, and fitting heavier duty cables...

The firmware had a feature/bug which meant that you could go from forward to reverse just fine, but if you tried going from reverse to forwards, it would do nothing unless you held the stick centered for a second or so, and even then it only sometimes worked. It also didn't turn the motors fully on when the stick was at maximum throw. To fix it I modified the code used for my antweight ESCs, and carefully fly wired in the replacement microcontroller chip.

The cables were also pathetic, and got fairly warm even when running drill motors under no load, so I replaced them with cables of double the thickness. Also added an input capacitor which should have been fitted and wasn't, and beefed up some of the tracks to the MOSFETs which looked a bit weedy.

It's a classic case of the chinese reverse engineering a good design in the cheapest way possible; the circuit used is actually very good, but the implementation was lousy.

They now work pretty much perfectly, but were hardly plug and play! Still, not complaining too much; £13 for a featherweight ESC is fine by me

Firmware upgrade wired in (old chip shown next to the board)
DcvKDBQ.jpg

Cable upgrade and noise suppression (bottom board is the original)
2WSmRZo.jpg


(These were the ones I bought: http://www.ebay.co.uk/itm/RC-ESC-20A...item3f363a2e2a )

[mrsam]

What voltage would these work up to when modified?

[Rapidrory]

Despite the fact they say 8.4v on the packet, I've run them up to 13V fine, and that was before all the mods. I went through checking the data sheets for every component I could, and none of them were rated for anything less than 20V, so I think they're fairly safe at 13V.

The board was surprisingly more robust than the spec said; the MOSFETS used could handle 32A continuous and 120A peak according to the data sheet. Normally with these things, they just take the specs straight from the data sheets. I think they must have toned them all down due to the lousey cables not being up to it...

[Rapidrory]

The design was good enough at least that I may have to reverse engineer it for my heavyweight ESC..

[plargen]

wow ......if you get bored you could try getting these to work properly
http://www.ebay.co.uk/itm/320A-High-...item5d3bd80ccd

i got the first version which worked well and could happily run a 4wd bot over powered from 3s to 4s without getting hot but then they changed something and when you slam it from 1 direction to another they just stop

[Rapidrory]

TBH, for £2 I'm impressed it did anything! That sounds like a firmware issue, so the same trick might work. Definitely have to check out those for my heavy! :L You able to get a detailed picture of the circuit board? Would give me an idea of the work required to upgrade it..

[plargen]

i did have 1 but cant find it will take a new pic and post it up tomorrow

[Rapidrory]

Cheers What I really want to find out is what it's actual current rating is (put 320A through that and it will almost certainly explode spectacularly :P) and also if it can be run at / upgraded to 24v. I've spent £25 on my heavy so far, and the only part I'm lacking now is an ESC, so £16 wouldn't be bad if it could be made to work!

[plargen]

here are the pics hope they help

[Rapidrory]

Thanks I can't read the chip numbers though; are you able to see what the numbers on the main drive MOSFETs are?

[plargen]

the nuber on the bank of 6 fets is

IRL 3803
R128p
U6 Z0

the chip on the bottom is
H1123 GB
LM339