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May 18, 2019, 01:02 PM
Flying R/C since 1964
kallend's Avatar
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Making an inexpensive EDF centerburner


Make Your Own Inexpensive Centerburner

I have a dozen or so EDF models, most of which are of types that were/are equipped with afterburners. After buying some LED “centerburner” systems, I decided to see how hard it would be to make my own.

This project requires soldering skills, and access to a 3D printer and simple design software (such as the FREE https://www.tinkercad.com ), This article only describes the electronic part; fabricating the adapter to mount the LED unit to the EDF motor is not covered. Anyone familiar with 3D printer design software should have no difficulty in creating a suitable mount. Total cost of the electronic components for the system is less than $16. If you do NOT have these skills, I suggest you buy a ready made unit from one of the people who market them on rcgroups.com.

First, I found a suitable high output amber bulb that has it’s own inbuilt voltage regulator.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

This is very bright, and runs on anything from 9 – 30 volts. It’s current consumption when full on is only 300mA, and the four brightest LEDs are behind a lens that directs their light along the bulb axis. With a little fiddling assisted by a razor saw I was able to remove the yellow plastic bulb base and expose the inbuilt regulator and its connections. These bulbs are $16 for two at Amazon.

To control it without making a custom controller I found a 10 Amp ESC for BRUSHED motors. $14 for two from Amazon:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

It has a built in BEC too, which we definitely do NOT want since it is not up to the job of powering an EDF with retracts, servos, etc. The spec sheet shows a voltage limit of 9V when using the BEC, but it easily handles a fully charged 4S LiPo when the BEC is disabled and the ESC current drawn is only 300mA rather than 10A. To disable the BEC simply cut the red wire in the “servo” lead that goes to the receiver. THIS IS IMPORTANT! The black (ground) and white (signal) wires can remain intact, and the ESC will be powered by the red and black power input wires from the red JST connector. There is an on/off switch on the ESC. You can leave it in place. I simply cut it off and connected the wires together so it is permantly "ON".

I decided to limit the voltage input to the controller to 4S LiPo voltage, so on a 6S (or more) system I’d take the input from the balance connector tap at the 4S position (nominally 14.8V but higher when fully charged). This is plenty to power the LEDs to maximum brightness. I ran the setup for 2 hours continuously with no ill effects to the ESC – it didn’t even get warm to the touch.

The ESC was designed for surface vehicles and has “forward” and “reverse” output, with "off" when the stick is in the middle. The LED unit is insensitive to its input voltage polarity and will illuminate either way. If we just connect the ESC control lead to the throttle channel output with a Y connector, the LED will be full on at both zero throttle and full throttle. To prevent the LEDs coming on at low throttle I inserted a diode in the red lead from the ESC to the bulb (you can use either red or black lead, I used the red one for no particular reason). This blocks the current flow when the ESC output is “reverse”. Given that JR/Spektrum and Futaba use opposite throttle signal conventions (and I don’t know about Frsky, Taranis, Jeti, etc,) you will have to determine by trial and error which way around to connect the diode. You can’t damage anything by getting it wrong. Pretty much any diode with a current rating of 1A or more will work, even a dirt-cheap 1N4001 at $5 for 250 from Amazon (yes, that's $0.02 each). I used a Schottky diode (15 for $9 from Amazon) because it has a lower voltage drop, but this is really unnecessary).

With the system connected up as described, the centerburner is off when the throttle is below 50%, and progressively lights up as the throttle is advanced beyond this.

You will need to make a suitable mount to attach the LED unit to the rear of your EDF motor. I 3D printed one, basically an ogival shape tapering down to the LED unit diameter. The details of the mount will depend on both the size and the type of the EDF motor (inrunner or outrunner). You will need to leave a hole for the EDF power leads to exit, and possibly some cooling holes too depending on your motor. Be sure to attach the mount securely to the EDF. The LED bulb can be held in place in the mount with C/A or epoxy. Be sure to secure all wires so they can’t get entangled with the fan.

Total cost of the electronic components for the system is less than $16.
Last edited by kallend; May 22, 2019 at 02:47 PM.
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May 18, 2019, 04:28 PM
Registered User
union1's Avatar
Great article Kallend. Thanks for making this available.
Instead of using a diode, using a separate channel for the afterburner with a curve applied so the a/b lights up as required, then mix this at 100% with the throttle channel.
Works great on my F-22!
Latest blog entry: SR-71 for 2 x 70mm EDF
May 18, 2019, 05:42 PM
Flying R/C since 1964
kallend's Avatar
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Quote:
Originally Posted by union1
Great article Kallend. Thanks for making this available.
Instead of using a diode, using a separate channel for the afterburner with a curve applied so the a/b lights up as required, then mix this at 100% with the throttle channel.
Works great on my F-22!
Yes, I did that on my Mirage where I had a channel to spare. On my F-18 all the channels are in use for other things.
May 18, 2019, 07:00 PM
eat, sleep, FLY FLY FLY
Mr.frankenjet's Avatar
very nice, tks for posting
May 19, 2019, 01:20 PM
Fly as high as the sun
icarus the 2nd's Avatar
Good info!

Actually I did this a year ago already, I found a vid on youtube where a guy explained that you can drive the LED's intensity with a old brushed ESC.

I tried it in my old FMS F-4 70mm (EPS version) with success but I used a led strip that I glued in the exhaust ... it didn't hamper the airflow and wasn't blown out.

That's what I used:

https://www.banggood.com/5M-6072W-DC...p-1034235.html

or

https://www.banggood.com/12V-Pair-6-...p-1431087.html

You can even buy those a lot cheaper if you need only 1 metre.

Why did I stop using it ? Compared to the rcgeeks's centerburner or some other afterburner controllers (Xicoy comes to mind) it didn't have a flickering effect which for me is 75% of the afterburner effect ... the brused ESC method only changes the led's intensity.

Have also experimented with the led strip on the exhaust at the outside but I can't remember testing that in flight.

Kallend: don't want to hijack your thread, just posting the pictures and information I have. Maybe we can use all the info for improvement!
May 20, 2019, 04:20 PM
Don't let your meat loaf
Heatracer24's Avatar
This is very cool!!
May 21, 2019, 02:38 AM
Registered User
edwen303's Avatar
Thanks Kallend sharing this trick! Just tried and it worked with a 3s brushless power system.
I tried but failed before using Y-connection between brushed ESC and brushless(power) ESC for my light, the key is what you described "to disable the BEC in brushed ESC". Will try again on 6s EDF system tomorrow. So far I use 3s to power brushed ESC. The 70mm LED ring is from banggood.
https://usa.banggood.com/70MM-COB-LE...r_warehouse=CN
Also from amazon: https://www.amazon.com/GrandviewTM-6...39127010&psc=1

Actually it is not necessary to cut the red wire to connector, just lift up the plastic stopper with tiny pointy tool like tip of Xacto hobby knife, and pull out the red wire on the servo connector.
May 21, 2019, 02:52 AM
Registered User
edwen303's Avatar
Kallend: have you got chance comparing your system with RCGeek's center burner? Just curious, I didn't expect this inexpensive setup as bright as RCGeek's.
May 21, 2019, 07:44 AM
Flying R/C since 1964
kallend's Avatar
Thread OP
Quote:
Originally Posted by edwen303
Kallend: have you got chance comparing your system with RCGeek's center burner? Just curious, I didn't expect this inexpensive setup as bright as RCGeek's.
I haven't compared with rcgeeks, but I doubt he uses any different LEDs than I do. I have compared with two other versions that are on sale and its the same as one of them and brighter than the other.

The LED bulb I used is for the turn indicator on a car. It's plenty bright enough to be seen in broad daylight. That's why I chose it.
Last edited by kallend; May 21, 2019 at 07:49 AM.
May 21, 2019, 07:46 AM
Flying R/C since 1964
kallend's Avatar
Thread OP
Quote:
Originally Posted by icarus the 2nd

Why did I stop using it ? Compared to the rcgeeks's centerburner or some other afterburner controllers (Xicoy comes to mind) it didn't have a flickering effect which for me is 75% of the afterburner effect ... the brused ESC method only changes the led's intensity.
Flicker is easy if you have a spare channel and a Tx with a sequencer. Create flicker with the sequencer, mix with throttle, and use that channel to drive the afterburner controller.
May 21, 2019, 09:50 AM
Registered User
edwen303's Avatar
Quote:
Originally Posted by kallend
I haven't compared with rcgeeks, but I doubt he uses any different LEDs than I do. I have compared with two other versions that are on sale and its the same as one of them and brighter than the other.

The LED bulb I used is for the turn indicator on a car. It's plenty bright enough to be seen in broad daylight. That's why I chose it.
RCGeek's system uses yellow LED bulbs that shine backward like flashlight, running ~7 V. I posted the amp and wattage number on his RCG thread somewhere. Gooniac also has his own system.

It is great we can make our own system for a fraction of the price, for an inrunner or outrunner with tailcone like FMS 1900kv 90mm system. Great summer project.
May 21, 2019, 09:52 AM
Registered User
edwen303's Avatar
Quote:
Originally Posted by kallend
Flicker is easy if you have a spare channel and a Tx with a sequencer. Create flicker with the sequencer, mix with throttle, and use that channel to drive the afterburner controller.
Will have to try it sometime. Flicker makes afterburner more noticeable during daylight.

Vaguely remembered testing LED on brushless ESC, it can flicker but not bright.
May 22, 2019, 10:01 AM
Registered User
bettsmums's Avatar

Home Made centerburner


Here is what I made for my Freewing 90mm F4 Phantom. I only sanded the side of the LED light so that it is basically complete. I had a GWS brushed speed control that was forward only so I didn't see any need to take the LED light apart because no diode was needed. I also thought that using the original streamlined fairing would be better because the aluminum might act as a heat sink. Mine also flickered just a little bit when it first starts lighting up before it hits full throttle. Do you think I am on the right track?
May 22, 2019, 10:44 AM
eat, sleep, FLY FLY FLY
Mr.frankenjet's Avatar
looks nice, have to look threw my old junk to find a brushed esc
May 22, 2019, 01:13 PM
Registered User
gooniac33's Avatar
Quote:
Originally Posted by bettsmums
Here is what I made for my Freewing 90mm F4 Phantom. I only sanded the side of the LED light so that it is basically complete. I had a GWS brushed speed control that was forward only so I didn't see any need to take the LED light apart because no diode was needed. I also thought that using the original streamlined fairing would be better because the aluminum might act as a heat sink. Mine also flickered just a little bit when it first starts lighting up before it hits full throttle. Do you think I am on the right track?
The GWS esc are worth their weight in gold!! I first got a hold of those about 10 years ago and they are awesome for this sort of thing! I used that on my 50mm L-39 back in the days and it worked awesome on up to 4s voltage. I use them as switches in several of my planes to date. But can not find them anymore... I just use the simple 2 amp ones with really good results. Just wish that they still made them!!

Also your method is very similar to mine. Mine is even simpler though! You would be surprised at how bright it is too!


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