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The RC-100 electronic switch looks simple, but if the switching and RX halves are not isolated, won't there be RFI issues?
-RCAddiction
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It is simple and the two halves are isolated, it's commonly referred to as a relay.
But yes, there may be RFI/EMI interference problems as with any device plugged into your receiver. If I was flying a 40% 3D monster I would be worried about all that servo extension wire too. The fact is every application has many possible solutions, some better then others. It's nice to have options and the RC-100 is an elegant solution for those needing an RC auxiliary switch, weather as a kill switch, auxiliary light switch, smoke pump switch or whatever.

Kai

Bob, NEVER split the wires on your switch harness. The diagram in post #14 shows a separate swithc that controls the power to the ignition module from the ignition battery.
On a standard magneto ignition engine all you have to do is bring a wire from the primary of the magneto to a switch and then to the engine case. You can either make it ( the switch) manual or servo operated. Mine is servo operated from the transmitter so I can kill the engine by simply using my Channel 5 switch on the radio.

Hi Jim,

Unless I am mistsken, Bob appears to have an electronic ignition module setup that uses a designated battery to power its operation. The only way to stop the electronic ignition from operating is to "open" the battery wires with a switch of some sort or by disconnecting the battery altogether. One could wire an adapter with the RC-100 in it that goes between the ignition module and the battery if they do not want to cut wires.

In your post, you are talking about a magneto setup, where the ignition is powered by a magnet triggering the coil and so forth, hence spark. I don't quite understand how Bob would ground out an electronic ignition setup as one does with a magneto.

In regards to all the other concerns about EMI, no circuit is immune to interference. Look at all wires as antennas. They can either pick up or give off energy based on what is being transmitted down the line, dependent on frequency and other factors. Knowing the design of the RC-100, it would be very difficult for it to have any energy communicated through the battery leads being switched and onto the servo wires on the enclosed circuit. Hence, if you have problems with energy on the battery wires to your ignition, this shows some inherent EMI problems with the electronic ignition and I'd be worried about things without an electronic switch. Inserting a switch or any wires of any kind could magnify a pre-existing problem.

Regards,

Thanks for the comments.

However, how close do the contacts in a relay have to be to conduct EMI or RFI? This is only a small air gap, right?

I thought there was a rule about keeping something carrying an ignition signal at least 12" away from something that can carry it back to the receiver?

Think of the separation as an insurance policy. You could place the receiver right on the ignition module and if all the shielding works, you probably won't have a problem. However, if the internal shielding fails, you develop a crack in the ignition module case, your resistor spark plug fails, or your grounding fails, you will most definitely get interference. With the separation, it would all depend on how severe the interference is, but you stand a much better chance than not having any.

First off, The contacts on the relay aren't the only separation that you have between the servo and the battery. The RC-100 setup is a relay that is triggered by a signal pin on coming from a microcontroller. The microcontroller senses the incoming pulse from the signal lineand flags the relay open or closed. Basically, it would be hard for any energy to come from the battery, conduct down through the relay, through the microcontroller and onto the signal line. If interference were present, it would be from the sheer field strength of any emitted frequencies that couple to the servo lead. Like I said before, if there is noise present in the battery line, you have bigger problems. So back to your original question - how far do the relay contacts have to be? Theory could tell you, but one would have to know the RF energy present. The more energy, the less the distance, etc

Distance does equal insurance as stated in previous post. The RF energy falls off the further you get away from the source.

Michael

Over the weekend I got a chance to install the RC-100 in my 40% Carden Cap with an older 3W 140. It's just below the most forward part of the canopy which is about 8" from the ignition module. I didn't build this plane, but the ign battery and throttle servo are within 6" or so of the module. Anyway, the switch works like a charm I have it hooked to JR single conversion receivers, and activated by the snap button. I recently moved all my kills to the snap button and like it alot. The RC-100 is a keeper and I am satisfied. Thanks RCATS!