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Tony Nijhuis 50" Vulcan EDF version

Nightmare electrics!!

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TonyS11/09/2020 11:31:08
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1211 forum posts
327 photos

Peter,

Thanks very much for that, it makes a lot of sense and I'd be over the moon to use two Y leads and two of the Rx channels which might well work, however the setting up of this is way beyond me at the minute ( I feel pretty good with myself if I manage to find the Delta wing setting on my Tx let alone mixing channels).

Also I have a Spektrum Dx7 Tx which may or may not be able to handle channel mixing, I'd have to do some research.

All worth doing though if I'm ever to get this thing to fly. I guess I'll add learning a bit about the proper use of my Tx to the list of processes needed to get this one finished..

Thanks again for the input.

Tony

PeterF11/09/2020 12:07:06
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578 forum posts
740 photos

Some transmitters have the ability to specify that the model has 2 engines and the Tx then allocates 2 separate Rx channels for the 2 throttles without the need for any mixing. I do not use Spektrum so do not know your specific Tx programming details.

TonyS11/09/2020 12:15:50
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1211 forum posts
327 photos

Thanks again Peter - I'll dig into the manual over the weekend yes

Nik Harrison19/09/2020 10:55:47
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96 forum posts
163 photos

Tony,

I've had a similar problem powering 4 ESC but from a Spektrum Rx. It turned out that the Rx could only power any 2 ESC at a time. The current drive from the Rx was insufficient. I used an op-amp to make a unity gain amp and the extra drive capability made it all work OK. Since found that there was no need to make one as I've now found a commercial product that does the same.

Try this

Cheers,

Nik

TonyS19/09/2020 11:06:21
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1211 forum posts
327 photos

Nick,

you’ve made my day.
Last night I tried what was my last idea and that was a proprietary 4 into 1 hoping it was my soldering that’s was defective. No joy, in fact, one of the retracts stopped working. This supports your idea that the current from only one ESC isn’t enough to drive signals to 4 motors and power three retracts and three servos.

I’ll be buying some of those beauties and will update later....

thanks again.

tony

William Macleod19/09/2020 11:23:51
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134 forum posts
69 photos

Hi Tony,

I am trying to setup two motors and esc's to one battery on a foamy Canberra

I am finding similar issues as you are. I had no problem with a foam vulcan with two pushers wired as suggested in the responses although one motor would not always start ( randomly I may add) till the other was at about 1/3rd throttle.

On my Dynam C47 the wiring seems to be both esc's with red wires intact connected through a "y" ,lead to the Receiver. no problems ???? How does that work?

Mind you many years ago I had two small edf's that ran off one Esc without any problems.

I am also running out of ideas so will just disconnect both red wires on the "Y" lead and solder in a Ubec through the battery lead. Any other ideas gratefully welcomed.

Bill

 

Edited By William Macleod on 19/09/2020 11:24:23

Edited By William Macleod on 19/09/2020 11:53:37

PeterF19/09/2020 13:34:37
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578 forum posts
740 photos
Posted by Nik Harrison on 19/09/2020 10:55:47:

Tony,

I've had a similar problem powering 4 ESC but from a Spektrum Rx. It turned out that the Rx could only power any 2 ESC at a time. The current drive from the Rx was insufficient. I used an op-amp to make a unity gain amp and the extra drive capability made it all work OK. Since found that there was no need to make one as I've now found a commercial product that does the same.

Try this

Cheers,

Nik

Nik,

Glad I was not imagining coming across this problem before. The op.amp. solution is I think the same little device that E-Flite have in their 3 way lead for some of their retract sets, to make sure that the signal is powerful enough to run 3 retracts.

It also avoids the need to set up a second throttle channel on a mixer, especially useful if the Tx or Rx channels are fully spoken for.

William Macleod19/09/2020 13:47:20
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134 forum posts
69 photos

Peter.,

 thanks for the link I have ordered one. So does the signal booster just plug in between the Receiver and the esc "Y" lead? Bill

Edited By William Macleod on 19/09/2020 13:48:05

Edited By William Macleod on 19/09/2020 13:48:21

Craig Carr19/09/2020 14:44:01
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734 forum posts
519 photos


That’s very interesting Nick, thanks for posting.

Peter, whilst I’ve never had a problem on my vulcan with the 4 motors, very occasional one of the 3 retracts might stop working (on a 3 way splitter lead). I’ve swapped the units for replacements and it still occasionally happens. But switch everything off and and on again and hey presto they often start working again  ....  would you recommend one of those on the retract circuit ?

keep persevering Tony. I had mine out on Tuesday. Wheels down flight thanks to the aforementioned intermittent issuefrown

660c610a-71ac-46fb-ad0d-184afba20b8d.jpeg

811de78e-16bb-412e-8994-dfc48037bd58.jpeg

636bcfa0-ca0a-4b3f-a596-a691806ad907.jpeg

 

Edited By Craig Carr on 19/09/2020 14:47:49

Nik Harrison20/09/2020 13:08:25
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96 forum posts
163 photos

Tony,

There maybe a bit a confusion setting in. The (poor) signal I'm referring to is the control signal (white core) from Rx to servos/ESC etc. The main power to the Rx/Servos is supplied by one of the ESC units and this is not normally a problem unless you have too many servos in the system. Typically it may supply between 3A and 5A depending on the ESC type. I have tended to use a UBEC instead of the ESC supply.

The Rx I used was only capable of supplying around 2mA of drive on the white servo signal. I had used the same Rx driving 4 ESC successfully but with a different ESC setup it could only work with 2 ESC. The opamp was used to boost the white signal so that it could now supply upto 50mA current drive. This cured the problem.

So a single opamp was used to boost the throttle signal which then successfully fed the 4 ESC units via a 4way connection. You do not need 4 boosters.

I have also used this "boost" technique when having problems driving 2 servos from same Rx signal, i.e. rudder and nose wheel steering. Either servos worked OK on its own, but connecting both with a "Y" lead had them go crazy. Solved by using a "boost" for each servo which ensured that the servos could not interfere with each other. Again problem solved.

Hope this all helps to sort out your problem. The examples I've mentioned all happened on the same model and I was scratching my head for some time before I settled on a solution. Don't give up I'm sure you'll get there.

Cheer,

Nik

Martin McIntosh20/09/2020 15:05:53
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3579 forum posts
1231 photos

Any chance of a sketch of the op amp cct please? I shall be quite capable of building it and it could solve one or two problems of my own.

Nik Harrison20/09/2020 16:01:17
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96 forum posts
163 photos

servo dual amp driver.jpgMartin,

No problem. The only reason I did not include the drawings before is that not many seem to be used to using a soldering iron these days. wink Have fun.

Craig,

I'm sure this would solve your gear problem.

Cheers,

Nikservo single amp driver.jpg

Martin McIntosh20/09/2020 16:15:27
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3579 forum posts
1231 photos

Thanks Nik, simple enough.

One of my problems is that certain HK retracts no longer work with their own Rx`s because they require a 5V pulse whereas the Rx`s only output 3V. Earlier units work fine and of course I may as well bang my head on a wall than get them to sort it out. This cct may also help to sort out multiple fans not running up to full speed at the same time.

Edited By Martin McIntosh on 20/09/2020 16:21:52

Nik Harrison20/09/2020 16:17:14
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96 forum posts
163 photos

Martin,

Having looked at the drawings as shown it is difficult to see the opamp name. It is a TS358, only because I had these in my spares box. Any 5v operating opamp will do. The package I used was a DIL 8pin device.

Cheers,

Nik

Martin McIntosh20/09/2020 16:23:42
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3579 forum posts
1231 photos

Cheers, I still have a few various types kicking around from my electronics days.

William Macleod20/09/2020 17:01:07
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134 forum posts
69 photos

Sorted it out. What you do is;

1. buy the lead as discussed above

2. before it arrives complete the wiring using one battery.

3. be amazed that by connecting both esc's via "y" lead it works!

4 try it with removing just one red wire from one Esc ...still works !

so clearly all the problems disappear once you order and pay for the solution.

Test flight tomorrow. Bill

still confused!!

Edited By William Macleod on 20/09/2020 17:13:32

Edited By William Macleod on 20/09/2020 17:34:54

Nik Harrison21/09/2020 13:16:55
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96 forum posts
163 photos

Martin,

The opamp setup I used is a unity gain arrangement. It acts as a current amplifier not voltage. 3V in will give 3V out but the current drive is increased. If you want to increase the voltage then a couple of resistors are required. See diagram. If you decide to use it as a voltage amp then you also get the benefit of the current drive increase, so win/win.

Cheers,

Nik

opamp volts gain.jpg

Martin McIntosh21/09/2020 15:06:25
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3579 forum posts
1231 photos

Thanks again Nik, just what I need for the retracts.

TonyS24/09/2020 12:05:50
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1211 forum posts
327 photos

Well, not great progress here I’m afraid.

I’ve purchased the opamps and used 4 in total, three between the Rx and the three ESC’ S not supplying power to the Rx and one to the retract that’s now ceased to work. That done I’m still only getting 2 motors working and still have one main leg retract not functioning. Pretty much no effect therefore.

The last thing to try is putting two motors on a different channel then mixing that channel with the throttle channel.

if this doesn’t work look out for a part-completed Vulcan in the classifieds!

Tony

Nik Harrison24/09/2020 19:12:15
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96 forum posts
163 photos

TonyS,

Sorry to hear it has not worked out. My suggestion would be to simplify the problem by working through each one in turn.

1. Remove the throttle channel, which is your power supply at present, and use an alternative power source. Spare AA battery pack for example.

2. Remove all servo leads except the undercart channel. Find out why the undercart set up is not working. Check each leg individually - using a servo tester?

3. Build up to driving all three legs and see what happens.

4. Once the legs are sorted start adding more channels and check channels work as you go along.

5. Finally add your motors one at a time while still using the external power supply. Make written notes as you go along so you can remember what worked and what didn't. It's too easy to forget what you have/have not tried.

I find that when you feel like binning the whole thing it is time to start as simple as possible. Fix one problem at a time and you may find that things start to fit into place and other stuff starts to work. Don't give up.

Nik

PS  Forgot to add that if using both external supply and trying to run motors from your Lipos then you must remember to have a common 0V connection between them.

Edited By Nik Harrison on 24/09/2020 19:15:07

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