ohnas

Sorry- I'm still here. I changed my email address and wasn't paying attention to this page. My email is correct now so I will get questions.

mikemscott

single stick 8ssap conversion, PLEASE ANYONE OUT THERE KNOW HOW TO GET AHOLD OF OHNAS BY EMAIL, VERY IMPORTANT THANK YOU, [email protected], MY NAME mIKE sCOTT

Levels87

Ohnas. Could you please say what transistor you used on the PPM board output to invert the signal.

grotto2

My Feedback: (2)

It shouldn't be that critical, Levels.
There's an inverter diagram here.
A 2N3904 or 2N2222 would also work fine.

Levels87

Thanks for the reply Grotto2. I am currently struggling to get any output from the 118GP decoder board. I Have connected positive 5v and ground as can be seen in the picture from ohnas with the signal (shown in the picture earlier as PPM/PCM) pin from the tx module socket to the DSC input of the receiver. The orange from the receiver board is not connected to anything. I am only getting 1v at the PWM outputs so I tried connecting the orange PWM + to +5v as well but no luck. Any thoughts what I am doing wrong? The decoder board is confirmed to be working when I connect it back onto the receiver board.

grotto2

My Feedback: (2)

Levels-
Maybe put the decoder back on the receiver and scope a couple of points. Orange may be a +3V regulator output that supplies voltage from the decoder board to the receiver board. Yellow may not want a voltage higher than 3V from the receiver....Whatever it wants you must duplicate it. Any chance your DSC is dead?

Levels87

Well I am delighted to say I have now got this working fine. The problem I had was that the signal for the module needs to be a positive pulse and I was getting a negative one to start with. That caused me to have alternating red and green LEDs on the module. I have built a signal inverter on breadboard and combined it with the voltage dropper for neatness which sorted the problem. I was also using the signal output for the module to feed the decoder board when I should have been using the DSC output instead.
At the moment you can change between PPM and PCM512 by just swapping over the plug to the module input. The single wire is for PCM and the three wires for PPM as the + and - are required to power the decoder and converter. I am going to make one further change to make it switchable between PCM512 and PPM by putting a switch in the back where the CCPM switch would have been fitted if they had decided to go ahead with that option. Here are some pictures.

vic101

Great work!

Please post a picture showing the DSC source on the transmitter, that's the only missing step for me..
I'm using a JR module so I don't need to invert the signal.

Thanks in advance.

Vic

vic101

Ah, wait,

I see that you have already posted this - apologies, I'm doing this as a monkey-see monkey-do method.

Thanks for your and the OP's help, I'm rushing off to do some soldering!

Levels87

Just to make it clearer here is another picture.

dhal22

Way above my head. Nice work guys.

vic101

Perfect, thanks again!
Vic

Rockbud

Not sure if this old thread is still active, but I am attempting the same retrofit on my Futaba Single stick radio. I have acquired all of the parts with the exception of the transistors, and could use some help in their wiring. Both ohnas and Levels 87 have provided some great pictures, but I'm still at a loss for the transistor connections. Any help would be immensely appreciated.

Regards,

Rick

Levels87

Hi Rick. I am rather pushed for time at the moment but will draw you a diagram of the signal inverter/voltage regulator as soon as I have time. It is all pretty straight forward and can be made on a small piece of breadboard.
Regards Jonathan

Rockbud

Jonathan,

Thank you Sir! and please take your time. My project is just getting started. Also, with only PCM 512 to start with, have you encountered any issues with stick resolution? The Futaba single stick was my first radio, expensive too for 1990. I fell in love with it immediately for flying helicopters and believe it may do justice for todays quadcopter.

Thanks again for you efforts on this.

Rick

joeytowmotor

I have been collecting these transmitters for many years. I will convert one of them soon. You did a fine job on yours! Thanks and fly safely.

dhal22

I have one nib but have never used it.

Levels87

Since doing this project I have come across a much better solution for the signal inverter. They are made by Tarot and sold as SBus converters for their gyro systems and they are really tiny and cheap.

Here is a link to buy one

https://www.ebay.co.uk/itm/Tarot-ZYX...637a%7Ciid%3A1

dhal22

Nice. Thanks a lot.