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Old Jul 17, 2015, 08:59 AM
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DIY 4x Brushed ESC (4.2A)

Hi!

Here is my small DIY brushed ESC design for use for micro copters.
I use it together with a cc3d atom board and 7mm DC motors.
The setup runs on 1S. The cc3d is configured to output 8khz pwm on the servo outputs (only 125 steps but that works fine)
as desribed here
You might have to recompile the gcs gui in order to allow setting 0 as pwm minimum, recent versions allow only settings from 500 and above
(there is a single define somewhere in the gcs gui code, simply grep for 500 in the gcs directory).

Parts list:
- 4x IRLML2502
- 4x 100R resistor (0805 package)
- 4x 10kR resistor (0805 package)
- 3x 4.7uF ceramic capacitor (0805 package)
- some prototyping pcb (the one with dots, not with lines)

Actually there is no schematic, just copy what you see on the picture and you are fine. In principle its just a 100R gate series resistor and a 10k pulldown on the mosfet.
The motors attach to the FETS (Motor -) and to the Lipo + bar.

Regards,
Simon
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Last edited by fishpepper; Jul 18, 2015 at 02:14 AM.
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Old Jul 17, 2015, 05:03 PM
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Cool! That's a bit more elegant than what I was going to do. :-)
From this though, I an change the format to inline on each, since it is apparent what to use and how to connect. I have all the parts except the additional 100R resistors and 4.7uF capacitors. I'm a little confused as to why only 3 caps. Looks like 1 cap each for two of the motors and then the other two share one cap. Is that right?
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Old Jul 17, 2015, 06:09 PM
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That is cute, on a 5x5 grid.

1002 resistors are 10K ? (1 K is too low anyway)

Three capacitors are in parallel between "+" and GND
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Old Jul 18, 2015, 01:42 AM
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Yes, you are right, 10K (i'll fix that in the first post).

The capacitors are all in parallel, just to get some capacity. You can use whatever you have.
Try 4x 3.3uF etc. It might work without capacitors as well...
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Old Jul 18, 2015, 09:48 AM
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Sorry had to ask this, could you post a connection diagram as the picture alone is quick confusing amd is not really clear.
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Old Jul 18, 2015, 11:34 AM
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ok, here you go. this circuit is basically replicated 4 times on the pcb.
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Old Jul 18, 2015, 12:05 PM
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RTFQ sell a pre made brushed ESC I believe

E: http://www.readytoflyquads.com/brushed-motor-driver
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Old Jul 18, 2015, 12:11 PM
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I think you are talking about this one:
http://www.readytoflyquads.com/brushed-motor-driver

Mine is so easy to build and costs all in all <$1 so i don't see any reason to buy a pre made one
Additionally i guess mine is only 1/4th of the weight of that one.
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Old Jul 20, 2015, 09:59 PM
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Plus, I am not going to put all four on one board. I'm going to make individual ones. Aaaand, just want to make them myself, regardless of price.
I actually now have a faulty PC motherboard that I can rape for parts. XD
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Old Jul 21, 2015, 04:59 AM
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Quote:
Originally Posted by fishpepper View Post
ok, here you go. this circuit is basically replicated 4 times on the pcb.
Great. Thanks.
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Old Jul 21, 2015, 07:55 AM
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Please note that a proper circuit would have a fast shotky diode across the motor connections (reversed) as the motor is an inductive load.
However the Uds voltage (20V) of the mosfet seems high enough that it survives whithout this diode. If you have a larger motor or run on more than 1S you might want to add that diode.

However all of the cheap china copters that i opened up do not use that diode (obviously for price reduction).
My CJMCU and CC3D based copter already have multiple hours of flight time and all work fine
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Old Jul 22, 2015, 07:52 AM
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But that uses 7mm motors. Most do. I'm using 8.5mm motors. Probably crappy, inefficient ones too.
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Old Aug 09, 2015, 08:37 AM
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OK, I'm finally revisiting this after quite a bit of distraction. LOL
I have the IRLML2502 mosfets, but now I'm wondering, since I'm using 8.5mm motors, should I get some 6A mosfets, or would that shotky diode do the trick? The IRLML2502 mosfets I have already burned through 2 on another micro that I'm using 8.5mm motors on, but it doesn't have a shotky diode. I'm using 1S 30C batteries, if that matters.
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Old Aug 10, 2015, 06:40 AM
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Seems Schottky diode comes in lots of flavors. What should I look for? Something with a similar rating as the fet? Like 20v and some amount of amps? Most I see are around 1A, but I'm not sure that's enough.
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Old Aug 10, 2015, 11:31 AM
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Quote:
Originally Posted by MrSatoV View Post
Seems Schottky diode comes in lots of flavors. What should I look for? Something with a similar rating as the fet? Like 20v and some amount of amps? Most I see are around 1A, but I'm not sure that's enough.
"1S 30C batteries" is meaningless without the capacity. Suspect 500mah 30C, delivering 15 Amperes, perhaps 30 Amperes peak.

Schottky diode 20v 1a should be good as conduction time is short and not continuous. These protect the MOSFET motor drivers. Installed electrically across the motors and reverse biased so they normally do not conduct.
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