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Old Aug 09, 2008, 07:09 PM
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I was thinking of using an ESC to drive a PC fan. A few questions were:
1) what is the power rating for PC fans.
2) can the flea ESC be used for the same
3) can the code be modified to interface to a reciever. It appeared to me that the ESC only runs a motor for a fixed duration.
4) Is any 6A rated ESC OK for this application.
5) finally I read that the PC fan motors have hall effect sensors. I dont know how that affects.

Thanks
Sumit
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Last edited by cimulation; Aug 09, 2008 at 07:12 PM. Reason: Corrections
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Old Aug 09, 2008, 07:49 PM
7000mw of raw power!
rich smith's Avatar
New Hampshire (not the old one)
Joined Dec 2006
5,986 Posts
David,

Thanks for clearing up filename confusion for me. I'll try the new TIMEOUT but best bet may be start with Barnhards code and put in your changes. Hope docs are accurate cuz that's what I was doing when I blew the ESCs.

USB power is used with no motor attached. This get's me in the ballpark. BEC or UBEC is Universal Battery Eliminator Circuit which is adustable switching power supply used to replace batteries and the crummy linear regulators built-into most ESCs. Best $5 lab supply around. My $600 HP is gathering dust. In final stage a real battery is used like shown in my original post.

Biggest motor used (BW) draws .85-.9a with 3.8x8 prop. Startup currents are rarely double that (scoped) and anyway my 3000mah battery can handle 80a easy. This is not likely the problem since all ESCs are tested before mod with same sources and none ever failed.

Motor occasionally (~200:1) does start on it's own and then runs fine so I know I'm close. It's tantalizing. That and easy mod are why 6a Turnigy is so much more attractive than Towerpro or Flea approach. Then a much lighter ESC will be designed for my final application. Need to "get my feet on the ground" first.

-Rich




Quote:
Originally Posted by David T
I think it must have been fblmc101.asm. I don't remember changing the name but I must have to simplify it slightly. I have early versions with fblmc101.asm and personal file name extensions so that must be the one I started with. Sorry for misleading you.

I think you could try changing compScanTIMEOUT to 48000 as per the original version; this will allow more time for the motor to turn during startup.

I don't think USB will drive a motor and I don't know what "4a BEC set for 8.4v" really means. Bernhard referred to startup currents of 20A in discussions. I think I set my PSU limiting to 1A in testing without a prop. Although old it is a high quality one that I'd expect to sustain a surge without fading. Is it possible your device cannot drive startup loads? You seem to be very close if it runs with a manual start.
David.
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Old Aug 09, 2008, 07:59 PM
7000mw of raw power!
rich smith's Avatar
New Hampshire (not the old one)
Joined Dec 2006
5,986 Posts
Sumit,

PC fans are 2 pole and our ESCs are for 3 pole motors. There is no way to make it work. Many people ask if they can use PC fan stators to make BL motors and are dissapointed to find out you can't. Wrong number of "nuts". They only draw few ma and it's a real trick to make them start in the right direction. Easy with special ICs though. Wish I was having as good luck with these BLMCs as I did designing fan controllers.

-Rich



Quote:
Originally Posted by cimulation
I was thinking of using an ESC to drive a PC fan. A few questions were:
1) what is the power rating for PC fans.
2) can the flea ESC be used for the same
3) can the code be modified to interface to a reciever. It appeared to me that the ESC only runs a motor for a fixed duration.
4) Is any 6A rated ESC OK for this application.
5) finally I read that the PC fan motors have hall effect sensors. I dont know how that affects.

Thanks
Sumit
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Old Aug 09, 2008, 10:26 PM
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Joined Nov 2006
14 Posts
Rich,

Thanks for your quick response. I am going to attempt this. Had some more questions:
1) what is the ISP programmer you are using with ponyprog for the Turnigy. Do you have a schematic.
2) You mentioned free form flight with the esc. What does that mean. I unerstand that the flea program does a timed flight and David has modified the program.
3) Can I use it with a 2-3 cell lipo.

Thanks
Sumit
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Last edited by cimulation; Aug 10, 2008 at 08:38 AM.
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Old Aug 10, 2008, 10:48 AM
7000mw of raw power!
rich smith's Avatar
New Hampshire (not the old one)
Joined Dec 2006
5,986 Posts
Sumit,

1. I use a ten cent cable to program AVR. One end has db25 for PC parallel port, other end 6 pin female SIL for the chip/board. I call it the GRVSOI cable. Two LPT pinouts are used by me: BASCOM and STK. BASCOM pinout for DOS is what I use 99% of the time for productivity reasons. I wrote C program over 10 years ago to download. WINDOWS girls are better off w/STK which is original Atmel dev kit pinout and compatible w/Ponyprog, AVRdude(GCC), etc.:

Code:
LPT      AVR
18 ..... ground
 9 ..... reset (1k series resistor if cable is long)
13 ..... vcc (not needed if target is self powered)
 6 ..... sck
10 ..... miso (only required for verify)
 7 ..... mosi
I build many of these and scatter them throughout the building because the cables get misplaced often. I shun the Dragon, avrISP, and other types that use serial or USB and need special chips just to interface. 6a ESC has nice in-a-row pads for downloading that take less than minute to tack on. See them in the pic?

2. FF means no transmitter. I've built fully autonomous aircraft that use GPS and/or compass for navigation and now trying to reduce size to minmum.
If I get it working next step is port to 1gram 1 cell "Ebay" ESC then design one even smaller. Bernhards Flea program is not FF, it's an RS232 demo I think. David added FF function.

3. I've tested the ESC with 2 and 3 cell and, by shorting reg, 1 cell.





Quote:
Originally Posted by cimulation
Rich,

Thanks for your quick response. I am going to attempt this. Had some more questions:
1) what is the ISP programmer you are using with ponyprog for the Turnigy. Do you have a schematic.
2) You mentioned free form flight with the esc. What does that mean. I unerstand that the flea program does a timed flight and David has modified the program.
3) Can I use it with a 2-3 cell lipo.

Thanks
Sumit
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Last edited by rich smith; Nov 05, 2009 at 07:07 AM. Reason: code for lineup
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Old Aug 10, 2008, 12:38 PM
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1,082 Posts
Rich, Sounds like you have the power supply side covered. I hope the timeout works. On a slightly different topic do you know what it would take to extract and restore the original program? I only need the FF feature at one event a year and like the standard Turnigy software. If I read the device and save the program memory as a .hex file, the eeprom as .eep and note the fuse settings, should I be able to restore those later? I think I tried this but could not get it working.
David.
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Old Aug 10, 2008, 01:26 PM
7000mw of raw power!
rich smith's Avatar
New Hampshire (not the old one)
Joined Dec 2006
5,986 Posts
David,

Always been a big issue with micros and the AVR series are pretty much immune to reverse engineering. Once the lock bits are blown that's it. I never read my own chips, didn't even put that function in the loader I wrote. Different story with PIC, 8051, COPS, etc..

Spent some time in China getting code out of old products because company no longer had source due to "disgruntled employee" or "deceased firmware engineer" syndrome. Nitric acid drip, blow aluminum runs, probes under microscope. There's only one thing I hate more than writing PIC assembly and that's disassembly. Worlds worst instuctions set. 8051 not much better.

AVR no-can-do despite what some scammers try to convince you of.

I'd give my left arm for that Turnigy code. As ESCs go it's da bomb!



Quote:
Originally Posted by David T
Rich, Sounds like you have the power supply side covered. I hope the timeout works. On a slightly different topic do you know what it would take to extract and restore the original program? I only need the FF feature at one event a year and like the standard Turnigy software. If I read the device and save the program memory as a .hex file, the eeprom as .eep and note the fuse settings, should I be able to restore those later? I think I tried this but could not get it working.
David.
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Old Aug 10, 2008, 01:50 PM
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OK. Just to clarify I'm not looking to disassemble, just squirt their hex back into their ESC later. However, after further reading I think you have answered my question.
Thanks. David.
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Old Aug 10, 2008, 03:32 PM
7000mw of raw power!
rich smith's Avatar
New Hampshire (not the old one)
Joined Dec 2006
5,986 Posts
Yeah, if you got hex, you got source (and versa visa).

Incidently Quax tells me he's got many new versions of his Flea code some of them using m88. I'm waiting to see if there are any links before I dig in. Also occurs to me your older versions may not be FF which explains why no response to pushbutton. Maybe no LED either. Gotta look at those again.


Quote:
Originally Posted by David T
OK. Just to clarify I'm not looking to disassemble, just squirt their hex back into their ESC later. However, after further reading I think you have answered my question.
Thanks. David.
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Old Aug 10, 2008, 05:50 PM
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Yes, the older versions are not FF and did not have the button enabled. They are an evolution from making it work with a radio and then replacing that signal with a push-button controlled timer.
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