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Sep 20, 2016, 05:42 PM
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Mini-HowTo

DIY brushless ESC signal converter (for Delta Ray)


This DIY converter takes brushed motor output as input to a brushless ESC. The brushless ESC uses modified BLHeli firmware to interpret the signal coming off of the Delta Ray receiver.

Previously I posted a brushless conversion of a DR receiver with burnt mosfets (motor runs without throttle input). Rather than replace the mosfets, signal was taken from the input to the mosfets' original location. Also posted was a build summary of a new brushless DR build using that receiver.

However, the goal of this build is to go brushless WITHOUT modifying the original DR receiver.

Imboeschi published a voltage divider schematic with his modified firmware as one of several ways one may convert the signal for use with brushless ESC and motors.



My concept is to make this circuit with connectors so that it is plug and play to the Delta Ray receiver. The RX is not modified and can be returned to stock if one wants to do so later - (why?) - this would allow for removing the receiver at a later time and replace or use it for a scratch build, or to keep the motors and ESCs and sell the original plane.

This is a very inexpensive project, components being <$4 dollars per motor. See Imboeschi's hardware documentation for resistor and diode specifications

Parts
1 Servo Y or 2 extension cables
2 Resistors (1.5k used)
2 Diodes (BZX55C3V9 used)
2 JST-RCY connectors with leads



Above, the parts are laid out roughly as they will be soldered.



Above, the parts are partially assembled for testing. Voltages were observed, as follows:

- With source battery @ 7.77v the output at the ESC connector was 3.60v using a 1500 ohm resistor, 3.56v using a 1800 ohm resistor, and 3.52 using a 2k ohm resistor.

- With source battery @ 8.35v the output at the ESC connector was 3.64v using a 1500 ohm resistor

- In all cases the voltage is high with throttle off (presumably why the motor runs with a burnt mosfet), but the motor ran when connected to the modified ESC on my brushless DR. IIRC, the firmware has a checkbox on the PC interface that can invert the input.



And above is the converter after soldering but before being joined to a twin for a common ground with shrink wrap over a small plastic backbone for strain relief and to protect the components. I was going to use the Y to join two converters, but I've decided to solder them together at the ground and save the weight and parts.



Finally, above are the left and right motor converters joined and ready for a final wrap.

Next step – a battery harness for connecting power from battery to receiver, ESCs and motor. If using 3S or 4S for motors and ESCs, then a 2S voltage regulator will need to be included to restrict voltage to the receiver. Alternatively, hardware documentation linked above illustrates a capacitor that can be changed to allow 3S power to the receiver.

11 Oct 2016 edit - Hooking the harness up to both of the brushless DR motors and modified ESCs using a nomal, good DR receiver I'm getting an inverted throttle signal - so motors calibrate at full throttle and run at full on zero throttle stick setting .... IIRC, the BLHeli firmware can be adjusted to invert the signal polarity.
Last edited by GottaZoom; Oct 11, 2016 at 10:30 PM.
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Sep 22, 2016, 11:16 AM
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These commercial alternatives to making your own power harness are new to me. Someone who doesn't want to collect parts and solder could adapt these for their own use.



Source: Banggood quad harness

First up above is a small quad harness that provide power to 4 small ESCs and it includes a output for power to a UBEC or receiver or LEDs. The 20ga wiring will limit the current, ESC, motor and prop - but I suspect this could be used with small ESCs and motors on the DR, plus

- using a battery adapter with the XT30 (depending on battery)
- carefully limiting power to the receiver via 2S main , or a step down regulator
- taking care to insulate unused power leads




Source: Banggood hex harness

The cables above provide heftier wiring and connectors, but there are now 6 sets of power leads, with no UBEC power tap.

For those unfamiliar with either of these XT connectors, this video may help.
Dec 06, 2016, 05:55 PM
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My main flying buddy made up a couple converter harnesses for his Delta Rays. He has changed out the capacitor on one of his bricks and today we tested running a motor off of that brick for each leg of both harnesses.

His max throttle signal voltage without the ESC hooked up was about 3.75v - 3.85v depending on the resistors used. We next used a Y connector to hook up the ESC and motor so that we could monitor voltage as the motors spun up off both 2S and 3S batteries. Full throttle voltage dropped to 3.50 volts.

The 2806 test motor seemed to run very nicely on both cell counts off of these 30A Afro ESCs where the DR Edition version of BLHeli was loaded.

I brought the ESCs home so that I can change the signal polarity/inversion parameter. Looks like he may end up trying these with the EDF motors so that he can run 5 more amps. He's planning to try modifying his 25A Turnigy Plush ESCs over to BLHeli and using those with either 1806 or 2304 motors that will be externally mounted.
Last edited by GottaZoom; Dec 08, 2016 at 11:04 PM.
Mar 07, 2019, 02:11 PM
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Did you ever use this harness in the air or only bench testing? Thinking about using it on a Delta Ray I have floating around.
Mar 07, 2019, 05:56 PM
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Wow, old post!

It seems to work OK with one motor, but I had problems trying mine with 2 motors .... it really needs to be looked at by someone with a much better understanding to see if it is feeding current across the ground or some other problem.

What has worked well for me has been the approach where the mosfets on the oem RX are removed and the modified ESC firmware is used. I've not tried any of the other approaches that Imboeschi originally outlined.

Well, that and simply replacing the oem receiver with something else .....
Mar 08, 2019, 02:24 PM
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I was going to simply replace the RX with a programmable AR636, but I like the option of using the OEM Rx. I might try the method of removing the mosfets that worked well for you. Thanks
Mar 08, 2019, 03:09 PM
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Quote:
Originally Posted by ssoaring
I was going to simply replace the RX with a programmable AR636, but I like the option of using the OEM Rx. I might try the method of removing the mosfets that worked well for you. Thanks
Seems like an advantage for the RX-based diff thrust. The AR636 is still a backup. Haven't done it, but expect the ESCs can be changed back from the Imboeschi version to regular BLHeli firmware (if even needed).
Last edited by GottaZoom; Mar 08, 2019 at 03:20 PM.


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