Futaba transmitters and Multiswitch encoders

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Futaba transmitters and Multiswitch encoders

Post by PedroGomez » Fri Feb 01, 2019 8:27 am

Hello guys:

It's my first post in your forum.

I’m a RC submarine Modeler, and my RC transmitter is an oldie Futaba FC-18 Campac.

This transmitter has a socket in the back, where the transmitter module is located. It allows the exchange of FM transmitters of 35, 40 or 70MHz, Frsky 2.4GHz and now Orange 433 MHz. I work in 35 MHz with my, this frequency allows me to receive 2.5 m deep in fresh water. In 2.4GHz with surface ships.
It is known that in 2.4GHz there is no reception under water, except dragging an antenna with a floating buoy.
I read in www.subcommittee.com , in a post writed by Tim Senecal, that the 433 MHz reception was about 1 meter. So I bought the transmitter module:
• Transmitter OrangeRX Open LRS 433 MHz 100mW (for Futaba)
• Receiver 9Ch 433MHz OrangeRx Open LRS
in Hobbiking.
The Futaba FC-18 transmiter has a special devices, called multiswitch encoders, and decoders which are connected to the receiver. This devices were designed to work in RC frecuencies, like 35,40 or 70 MHz. You can see the encoder in the transmitter, and the decoder, in pictures attached.

A few years ago I bought Hobbyking Frsky Tx Modules and Tx receivers, to work at 2.4 GHz. I could already see that with 2.4 GHz, the multiswitch encoder and decoder modules did not work.

The Encoder Module uses a proportional channel (channels 7 and 8 on radios F14 and F18) to generate 8 pulses that correspond to values of 1000 ms and 2000ms for the extreme positions of each switch and 1500 ms for the central position. These 8 signals are transmitted multiplexed to which a control pulse is added to separate the trains of values. The decoder receives these signals through the Receiver and through mosfet transistors it produces a commutation in each of the 16 possible outputs, which allows connect and disconnect 16 electric circuits. The signal of channel 7 or 8 of the receiver can be read with Arduino and see how those 8 pulses are produced and how they change when pressing the switches up, down or center.

With the Orange 433MHz modules, the same thing happens as in 2.4GHz. As I read in forums, the control pulse induces an error in transmitter or in the receiver in such a way that the received values do not correspond with the emitted values, which causes the circuits to connect randomly in the decoder. With Arduino it is clearly seen in the computer, as the values change randomly, without control.

Given that in this case, Orange Tx and Rx 433 MHz, the equipment, is Open LRS, my question is if it is possible to modify the programming in the receiver or in the transmitter so that these errors do not occur.

Sorry I can't attach pictures because after resize them to 200 kb, status said invalid

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Re: Futaba transmitters and Multiswitch encoders

Post by pierrotm777 » Sun Jun 23, 2019 3:17 pm

The MultiSwitch modules can't work on 2,4ghz or 433Mhz. Only one system accept that. Search OpenAVRc / X-Any on github.
This system is fully compatible with an original MultiSwitch module and accept also Multinaut and more

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