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Switches |
R. W. Stuart The two most critical switches in your RC system are the receiver on-off switch and the transmitter on-off switch, both of which must stay on throughout your flight. The rcvr switch connects the flight battery to the rcvr and servos and has variable loading more or less milliamps depending on how many servos are moving at any given time. A very heavy transient current flows each time you enable the rcvr, and rather low rcvr system voltage and high vibration requires good switch contact pressure. The transmitter, operating at twice the voltage of the rcvr, does not require as much contact pressure and has very little vibration problem unless you drop the transmitter. Most xmtrs have little plastic wings which guard the on-off switch from accidental tweaking as you are fumbling around trim controls. The slide switch supplied by the manufacturer looks adequate for the job and it is paid for! Bill Riley and I discussed the merits of the slide switch vs a good mini toggle and the slide switch won hands down on cost, but not much else. A good toggle will provide good contact pressure with a very positive dedent (never half way) and will give you both tactile and optical clues as to which way. I am sure that Bill will confirm that most of the cockpit switches in the jets are toggles or rockers. My personal rcvr switch system: the toggle is a 3PDT (three pole double throw) with two poles acting in parallel which provides redundancy; if one pole fails during flight, the other can carry the load. The third pole (middle of three) allows a little room for soldering and my total inherited stock is 3PDT switches, anyway. The battery cable red connects to the two outboard center lugs or common lugs, the rcvr connects to the two lugs of one throw and the charge red connects to the one lug of the other throw. I use a mini plug and jack for the charger connection. The result is a red (+) battery wire which is toggled between the rcvr and the charging jack, if on the rcvr is powered and battery does not see the other throw. If off the receiver is disconnected from the battery and the battery is connected to the charging jack and the battery may be off or charging depending on the charge plug. The black wire is continuous from batt, to rcvr, and to charging jack. When the soldering is done, the back of the switch is pasted up with silicone for insulation and added strength and the battery plug parts are taped to prevent them from disconnecting. I’ll make a wiring sketch for you. Physically the mini toggles are attractive, at least on the outside, and flex plastic boots may be purchased to make them fluid proof from the bat handle (out) side. When the toggle is thrown right the left lugs connect the center lugs try it with an ohmmeter. Do you want the bat handle to operate up-down or fore-aft? Arrange your mechanics so that the flying rcvr has the least chance of being turned off by flight line handling and by collisions with birds, trees, weeds, and other planes. Ground impact has never turned off any of my rcvrs- lots of parts came off of the airplane, but the rcvr was still ticking. See connection sketch below. 
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