Connect Tx to Rx via cable?

[tomarse]

Hey, im wondering if its possible to hardwire a tx directly to a rx. Ive searched these threads and a similiar post was posted but no definitave answer was given. I really want to keep the RC system (tx rx) because i have expirience in RC Helis.
Ive seen about extracting the PPM from the handset and delivering it to the RX but i have no idea how???

Any help would be greatly appreciated.

[Endurance]

Id say it can be done but not without a bit of hacking around in the receiver.

Since the receiver outputs a pwm signal youll need to locate the ppm signal somewhere before it gets converted to pwm. Taking the ppm signal out of the transmitter will be much easier. Installing a toggle switch somewhere on the Rx could easily switch from wired to wireless modes.

[GlowFly]

Some manufacturers make specific provision for this. I think JR provide DSC (direct signal connection?) which uses the trainer output from the Tx and connects to the battery connector or a dedicated DSC connector on the Rx.

So you may find it easier to use a Rx that already has such a connection and perhaps the trainer output of whichever Tx you already have.
--
Steve

[BushmanLA]

Someplace on the TX there is a pin that is outputting the un-RF-modulated control signal that is produced before hitting the RF part of the Tx. Probably in PPM form depending on the controller and mode.

Also somelace on the reciever is the de-RF-modulated output that comes after the RF part of the Rx.

You should be able to simply connect these two together along with a common ground wire and be ok.

The only thing is that on the Rx, the signal is driven by the RF block, so if you simply connect to it, you may be making some unhappy electronics. It would probably be best to break this connection, leave the RF side open, and connect to the rest of the Rx side from the Tx.

[rc404]

Futaba also calls it DSC = Direct Servo Control. Their website says:
High-end convenience feature which allows control/adjustment of servo function without sending signal through receiver. Requires optional DSC cord (FUTM4250) and DSC-compatible receiver such as R149DP and R113IP.

To do it on just any receiver would require a good bit of hacking.

You might also consider taking the trainer cord PPM output and building a "receiver". I've never done this, but it can be done with a shift register chip like a CD4015 or 74HC16. I'm sure there are other chips as well. If you search on terms like PPM decoder you should be able to find something.

[phil_g]

On the transmitter, its easy peasy. just pick up the PPM stream from the trainer socket. You might need a bit of level shifting or inversion to connect the tx & rx but it should be relatively easy.
If you dont mind getting an older rx to modify for the purpose, that should be easy too. On an older rx (ie not microprocessor controlled) the decoder is simply a standard shift register chip, probably cmos, possibly TTL, but either way you can find the serial & clock inputs easily as the data sheets are readily available. Thats where your PPM signal connects. A low impedance source will ensure that the the shift reg is driven by the tx rather than by the rx demodumator, or you could cut a land to make sure.
I wouldnt attempt it with a modern controller based rx tho, too many unknowns.
Cheers
Phil

[vintage1]

If in the UK. get a Micron RX kit and discard the receiver and use the decoder board only.

Its a shift register and a transistor to reset from the synch pause.


I should have a scarppy circuit somewhere

[Ron van Sommeren]

Lots of info on where to pick up the signals
http://users.belgacom.net/TX2TX/tx2tx/english/tx2txgb1.htm