Nik Harrison
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Everything posted by Nik Harrison
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Tony Nijhuis 50" Vulcan EDF version
Nik Harrison replied to TonyS's topic in Build Blogs and Kit Reviews
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 -
Tony Nijhuis 50" Vulcan EDF version
Nik Harrison replied to TonyS's topic in Build Blogs and Kit Reviews
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 -
Tony Nijhuis 50" Vulcan EDF version
Nik Harrison replied to TonyS's topic in Build Blogs and Kit Reviews
Tony, Simple test. What happens if you attach battery No2 first? Nik -
Electro mechanical retracts control board
Nik Harrison replied to jimmac's topic in Gadgets and Electronics
The above solution is a bit overkill, but a fun experiment. Phil had the right idea and if the motor stall is a problem, as high current drain etc, then just fit a resettable fuse. They cost next to nothing. Cheer, Nik -
Arduino programming for beginners.
Nik Harrison replied to Chris Bott - Moderator's topic in Gadgets and Electronics
I have to take umbrage with the last posting. I had problems with some coding that was sorted with a simple email. I would not fault the forum. When the IDE stopped working - again the forum sort me out. By the way I did not even know there was a manual. Cheers, Nik -
Arduino programming for beginners.
Nik Harrison replied to Chris Bott - Moderator's topic in Gadgets and Electronics
Other uses for hardware/software in our sport. 1. Arduino used to make a 2.4Ghz version of an old time reed Tx. 2. Same for single channel units. 3. I used a PIC micro to operate cargo doors and paratroopers on the TN A400 using only one channel. 4. Same for servo reverse and servo slows. I know you can buy such devices but making your own is more fun. Once you acquire such programming skills the projects you come up with will surprise you. I regard it as just another part of our sport. Nik -
Arduino programming for beginners.
Nik Harrison replied to Chris Bott - Moderator's topic in Gadgets and Electronics
Posted by Kevin Harton on 14/07/2020 07:35:42: Are there any scenarios within model flying where Arduino could be useful? I used the Arduino Nano to give voice announcements to my early model Dx8. See Voice Synth Here. I did post as "Giving voice to my Spektrum Dx8" -
New EDF Mini Jets- Hunter & Phantom
Nik Harrison replied to Tony Nijhuis's topic in Tony Nijhuis plan builders
Hi, did mine in Royal Navy colours just to be different. Used the FMS 11 blade 4s fan from 4-max as I had some 4s 2200 batteries. Weight (sans battery) 452gm. W/battery 684gm. Thrust (nose down on scales) with battery at 83% was approx. 600gm. Not flown yet. -
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Or you could use XT-90 anti-spark connectors. I use them and have had no problems with them. Cheers.
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Giving voice to a Spektrum Dx8
Nik Harrison replied to Nik Harrison's topic in General Radio Discussion
The Speech box was also operated at 3.3v partly because that is the voltage that the Speech Syth. uses. Using an Arduino Nano 33 BLE as the processor it all seemed to work. I say "seemed to" because when I changed the model selection on the Tx it made odd chirps. When I selected a model that used the trainer link the Tx went crazy again. Why changing the model selection should have such a profound effect is very strange. There was obviously too much current drain on the signals in the Tx so I fitted the unity gain opamps again, this time in the controller, to reduce the load. It worked out better this time as I only needed two opamps as the multiplexers supply two data streams. So instead of an amp for each signal it now only required two. This fixed that problem but now one of the lower voltage signals was not responding on the controller. Fix for this was to make the opamps amplify the signals. I fitted a rotary switch so that I can have up to 10 different scripts for different models and a Status button that will announce which script is selected and then run through the position of all the selected switches. Therefore you can know the switch positions while flying and not having to look at the Tx. One thing that you have to accept is the Chinese accent. It does make some words too similar. Example "Enable" and "Disable" do not stand out. I used "Engaged" instead of "Enabled". Just requires a bit of experimentation and imagination. The final bit I added was a nice loud alarm call if you left the Speech Controller on and were not using the Tx. -
Giving voice to a Spektrum Dx8
Nik Harrison replied to Nik Harrison's topic in General Radio Discussion
The Dx8 I had was well out of warranty so the next thing was to open it up. I admit I had to look in the manual to see how to do it. The first thing to discover was how the switches were organised. The three position switches were centre pin 0V and the two outer pins were signals. Therefore I only need to monitor two signals for every three position switch. The two position switches were just 0v and signal. Most signal levels were 3.26v but some were 2.4v. So the Tx works on a 3.3v system. Adding up all the signals required to monitor came to 15. I ignored the rotating switch just sticking to the digital stuff. My first thoughts were to use optical coupling devices to monitor the signals but decided in short order that there is not enough juice to drive them. I then tried unity gain opamps as they would have high impedance inputs so should not effect the Tx signals. This worked but the power source was a problem. I had planned to have an external power source drive the extra components required in the Tx but if the external power source was not there then the Tx went crazy. By crazy I mean unusable and chirping like mad. Obviously not a happy Tx. The solution I came up with was to use two 8 to 1 CMOS (CD4051) multiplexers and as these are happy to operate at 3.3v so they could be powered by the Tx power supply. The current drawn would be minimal and there was enough room under the SD card reader to fit two DIL chips. The use of the multiplexers made the number of connections between Tx and Speech box come down to only seven. This was important as I did not want to have a large connector on the rear of the Tx. -
As lockdown continues and boredom set in I found the below item on Youtube. **LINK** This reminded me of something I have wanted for some time, which was to give voice to my Spektrum Dx8. I even bought a Graupner MX-12 Pro set as one of the facilities it offered was voice on its switches. A lot cheaper than a Dx9. I didn't find it very satisfactory as the software to produce new voices left a great deal to be desired. So with nothing to lose I sent off for the Speech Synthesiser XFS5512CE from Banggood. There were a few requirements on Tx performance that I decided were important to achieve. 1. Tx must not be compromised. 2. Voice Controller must be removable. 3. Must function the same even if the Speech Controller was switched off, flat battery or even removed.
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