Make Your Own Micro ESC

Questions, Tips and Tricks about the transmitter, the electronics in the car etc.
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Posts: 315
Joined: Sun 13. Apr 2014 01:02
Location: Sedona, AZ USA

Make Your Own Micro ESC

Post by Ned » Sat 17. Mar 2018 04:13

When I first ordered some RC gear from several vendors, I ordered a couple of HEXTRONIK HXT900 servos for only $3.05 each from HobbyKing. I did this with the intent of making them into micro ESCs for brushed mag racing motors. Did so just in case I couldn’t find an ESC small enough.

Since then, after many more hours of searching, the smallest ESC for a brushed motor that I can find with reverse is the DasMikro 1S Bi-directional Brushed ESC With Break For Micro Racing Chassis ... rehouse=CN

I ordered one of these a week ago. I expect it will work with the HK-GT2E 2 channel transmitter which I believe is made by Flysky. This DasMikro ESC supposedly measures 18x12x4mm, a footprint of 216 square mm.

Today I experimented with making the HXT900 into a brushed ESC. I removed the motor, circuit board and potentiometer from the HXT900 case. To test the idea, I
1. replaced the servo motor with the magracing motor,
2. set the dial on the servo tester to the 12 o'clock position,
3. plugged the cable from the servo into the output side of the tester, paying close attention to the pins labeled (-). (+), & (S). The signal (S) wire is the light colored yellow wire.
4. plugged the cable from the battery into the input side of the tester, paying close attention to the pins labeled (-) & (+),
The motor started running as soon as I plugged in the battery cable.

I then turned the shaft of the potentiometer until the motor shaft stopped spinning. After that, I could control the direction and rpm of the motor by turning the dial of the tester. It seems to work but only several hours of running a car will confirm whether it can handle the amperage and provide enough variation in speed.The circuit board measures 12x9.5x3mm, a footprint of only 114 square mm. And it’s only 3mm thick.

The circuit board with the attached pot is by the white spur gear for size comparison. Before installing it in a car, you’d want to glue the shaft of the pot in place with thin CA glue then cut off the shaft to save space. Must also be sure you can find room under the body to place the pot. A small continuous rotation servo would probably be better for this application since it doesn’t have a separate pot.

Can anyone tell me if this homemade ESC will work with the FS-A8S receiver and the HK-5320 servo? Hobbyking told me that the FS-A8S is compatible with the HK-GT2E which I just received today.
See photos below.
FS-A8S receiver
IMG_20180316_204512-Resized.jpg (215.15 KiB) Viewed 1800 times
FS-A8S receiver
IMG_20180316_204745-Resized.jpg (246.74 KiB) Viewed 1800 times
I purchased this tester thru AliExpress for $3.38 delivered.
IMG_20180316_162801-Resized.jpg (129.5 KiB) Viewed 1800 times
This pic shows a HXT900 before it was disassembled as well as connections of all components to test control of mag motor.
IMG_20180316_162410-Resized.jpg (193.13 KiB) Viewed 1800 times

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