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Nov 21, 2012, 08:09 PM
Registered User
Hi Joe-

That's a good question... If you hook it up direct to the FET you would use the gate leg, if not mistaken.

By the way, I received a Deltang RX43d from Bob the same day Chris's controller came. It is my first and I am curious to test it out. Do you have the 43d version too? Or are you using the Rx46-2 you mentioned before?
Last edited by shagrug; Nov 21, 2012 at 08:19 PM.
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Nov 21, 2012, 08:46 PM
Registered User

I am glad that Chris's controller can take some onslaught!


I have used several DT receivers and they all performed great! I am using the 43d on my twin engine DH-8 design. I have a 42 that I am not using in a model, so I will test Chris's controller with it.

I may test the controller in my 1/72 scale MiG 15 design with the bimRC 20mm fan unit. I built a new 1/72 scale MiG to try the bimRC 20mm unit with a 6mm motor without success. It was drawing to much current, and the motor would loss power after only one flight. Chris mention that he could build a lighter controller for my 4.5 inch A10 project. However, I think it is a good idea to test out some motors and batteries with this controller, before I start working on the new A10!

Nov 22, 2012, 02:51 AM
Micro Jet Pilot
Chris T's Avatar
Originally Posted by Chris T View Post
as I said: red is black and plus is minus
Damn I should be careful what I say. This was a JOKE!!! I got a pm with a big ?
Nov 22, 2012, 02:55 AM
Micro Jet Pilot
Chris T's Avatar
Guys, please start the first tests with dedicated power and ground lines for rx AND blc. A star connection with battery in the center. Clear?

The signal input is servo signal, so connect it to the bl output of the dt rx.


P.S.: red is + and black is -

P.P.S: I have run that type of controller up to 3 Amps in the big squall before I exchanged it with the xl version. It can stand quite a lot.
Last edited by Chris T; Nov 22, 2012 at 04:36 AM.
Nov 22, 2012, 09:11 AM
Micro Jet Pilot
Chris T's Avatar

Further instructions

Hey guys,

the current version doesn't have stall detection nor upper throttle limit. The code is written so nominally you can put throttle all the way up and the throttle trim as well. This is with my DX6i. I am not sure if all transmitters have exactly the same range, so please when you go to full throttle the first time, put trim all the way down. When the rpm is stable, slowly move the trim to the center and watch the motor. If there are cuttoffs, pull throttle down immediately. I haven't put a limit in the code yet, cause I am not sure if there is one optimum setting for all motors. It should be save under all circumstances with throttle trim centered. You can get a bit more power with trim up, but if you watch power consumption, you will see that at a certain point the price is high for a bit extra rpm. The sweet spot is clearly away from the point were the dropouts start. With the current version I needed to put throttle range to about 120% to experience cutoffs, which I don't recommend at this time. If these cutoffs happen, this is due to wrong timing, because the driving pulses are so wide that the off time gets too short for a proper timing measurement. Then the current suddenly increases severely. Even with my big test motor that didn't cause any damage. It's not a rpm limit, it also depends on the inductance of the motor I think. With your feedback driving different motors, I think I will be able to limit throttle to avoid this risk and allow maximum power. I really believe if you don't change throttle range and leave it on 100%, it is already save now.

Stall: If the motor doesn't start spinning, put down throttle. It's not very critical since the throttle is ramping up slowly, even if you put the stick all the way up quickly. With trim centered, sudden throttle down to zero will stop the motor immediately. A very important feature to stop the motor quickly before a crash. If you suddenly drop throttle to about 10%, the rpm decreases slowly.

To help the motor start reliably in the same direction, the rotor must rest in a predefined position. If your bushings/bearings are very good the earth magnetic field can already help. Play around with the orientation of the motor on your test stand. A small extra magnet has proven to do this job perfectly. It will bring the rotor into a defined rest position. flipping the helper magnet will make the rotor start in the other direction. Reversing the motor leads as well. In the squall, the external magnetic field required for reliable startup in the same direction comes from the servo/actuator magnets wich are left and right of the motor. With both servo magnets oriented the same way and the coil oriented vertically, this is working great and makes it a cool system without additional starter magnet. The motor starts without external magnetic field as well, just sometimes it gets stuck in one of the two dead spots were no torque is generated. You can blow on the rotor while starting as well. That way you also define the direction of motion. Or if you see the motor get stuck on startup put throttle down, move the rotor by hand, then throttle up again.

Any questions left open?

Last edited by Chris T; Nov 22, 2012 at 11:26 AM.
Nov 22, 2012, 02:25 PM
Micro Jet Pilot
Chris T's Avatar
Dave, making the wires shorter is no problem. Go for the brick. RF Interference should be no problem I believe. But power modulation might be. If you make a brick, there's only one pair of power lines. You should keep those short and not too thin, or still use two pairs to connect the battery. Play around with it, you will find a setup that works. Maybe a bigger cap on power on the brick will help. It might even work without effort. I don't think it's critical to try it out. Worst case you disturb the rx.
This is what happend to Dave first, cause he got a beta sample with a very small 4.7uF cap (the first one I send out). Later I found out that my big test motor wouldn't start with this setup, so did his motor. After adding a bigger cap it worked. All other controllers I sent out were perfectly stable under all my test conditions.

Nov 22, 2012, 08:05 PM
Registered User

I figured it was a joke, but you had all of us thinking! Thanks for the new instructions. I am still on the road working, but as soon as I get home this weekend I will test out the new controller!

Nov 24, 2012, 01:33 AM
Registered User
Hi Chris,

I returned home from my 4 day work trip late tonight. I could not wait so I wired up your controller! I tested it with my DT Rx42 receiver and a few motors that I had made. The motors all started right up and ran, but they are cutting out after only 1/4 -1/2 throttle. It seems like they really want to turn up, but then they cut out. I am thinking that I should try a different receiver tomorrow.

Anything else that I should try?

Nov 24, 2012, 03:42 AM
Registered User
Joe- You are doing better than me.... My first try is with the rx setup below that I was using to test chips with (in my westknoxrc thread). It does not want to run at all, and acts like it is not getting any power or signal. The board is getting power, so no problem there. The signal is coming from the gate leg of the fet, as you can see below. Using the plantraco tx also is probably not a good choice, but this rig was all wired up and quick to try first. Throttle trim changes didn't help, all through the range.

I'll test it with a couple of other rx'es after supper, and see how it does. The motor coil hooked up has a 4.5 ohm coil, and runs fine with all the sensored chips I've tested. (A1442, A1448, AH5795, AH5798)

I don't think it will take long to figure out the problem.
Last edited by shagrug; Nov 24, 2012 at 05:27 AM.
Nov 24, 2012, 03:56 AM
Micro Jet Pilot
Chris T's Avatar
Dan wrong signal. You are using a pwm signal not servo. I told you in a pm

Joe I guess this is happening were the motor is jumping into the sync routine. Can you check what the rx is doing at this moment. Is it losing signal for a moment?

Nov 24, 2012, 04:10 AM
Registered User
Hi Chris- Oops- you are quite right! I forgot all about that, and it is likely the problem. In the pm you mentioned the deltang hookup- but that rx is for a different project. So it went right by me. I'll try it again in a few minutes....
Last edited by shagrug; Nov 24, 2012 at 04:42 AM.
Nov 24, 2012, 04:39 AM
Micro Jet Pilot
Chris T's Avatar
Joe how is your power wiring? Use a strong battery first. I believe you are knocking out the rx.
Nov 24, 2012, 05:22 AM
Registered User

Thanks- that fixed it, very simple... you can see the new connection below.

It starts fine now, but has the same problem as Joe. Around the half throttle mark it stops dead, and locks up. Runs smooth up to that point, and is turning the 32 mm prop at 10,500 rpm when it stops.

Playing with the trim does not seem to help, but does slow it down at the low range. I'm using a 160 mah lipo, so lots of power there.

I can try another rx if you think that will help. I don't have a dx6 tx- but do have a dx5e and dx7, if you think that will help.
Nov 24, 2012, 12:04 PM
Registered User
I've tried it again with the Hobbyking 6 channel rx below and my dx7.....

It runs worse now, stopping at 7650 rpm with the throttle about 1/4 of it's travel. The trim changes don't seem to help stabilize it, same as with the first test. The servo is just to be sure it has a good binding.

I'll look at it again later today, and mabe hook my simple usb scope up to it. I think I can make a vid capture with it, mabe it will help.
Nov 24, 2012, 12:10 PM
Micro Jet Pilot
Chris T's Avatar
Ok strange. This has not to do with trim or what I described before about coutoff at max throttle. This seems to happen, where the starting routine ends and were the sync mode starts. I moved this point to somewhere between 1/4 and 1/2 throttle. Dave's controller has this point still at lower throttle, but I figured that putting that transition to a higher throttle value improves startup of my big motor. Now every setup seems to behave different. I am quite happy I didn't sell any controllers yet I wonder if it has to do with kv of your motors. My motors have a much higher rpm at this point than 10k. The point is that the sync routine is actually modulating power a lot, but still is much more efficient. The lower the kv, the worse this gets. I would like to understand if the rx gets disturbed. Could you tell me if the servos / acts connected to the rx drop out too? What happens exactly with the motor. Does it restart and ramp up rpm again by itself? Do you have to remove battery to restart? I never have tested slow motors with props. It could be that rpm is so low, that the timing calculation fails due to timer overflow, but I really don't think that cause the sync routine runs down to almost 0 throttle, but to get into it you have to get over that critical point were you experience malfunction. So you probably never experienced that mode. My 10mm fan is running with this code version on 20mAh so I am a little confused. I have tested with an AR6300. Maybe somebody has a similar rx to test. But the code is running also on the squall board with onboard rx. If you have extra caps at hand you could test if additional blocking helps. I am pretty sure that it's not the blc failing by itself, but the system not working together. I have had these issues again and again too if you remember. Sorry, I hoped it would be a plug and play thing, I tested all your controllers, but the systems seem to be different. We will succeed. It can't be that I am the only one that gets these to run. If you give me more numbers we can find out where the differences are. What is rpm, current and voltage at the point of dropout? Videos would help too.


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