From the Archives

[Erfolg]

David I remember splits where an intermediate frequency would be given a colour combination of the the adjacent colours. The problem for me was (is) that my Waltron receiver transmitter combination (27) would be swamped by an adjacent split if their transmitter was near than my own, to the model. It was either that my receiver had poor discrimination, or the side band noise was large from the other transmitter. I do not know. What I did know, is that my models would go in as if someone had started transmitting on my frequency. Erfolg

[David Ashby - Moderator]

Hi Erfolg - I only got into R/C at the end of the 27MHz days but I remember splits being banned from wher we flew, what did you think of that Xmas pudding ?

[A.A. Barry]

Well, that is some bit of work, that was when idea's where one man's creation!  Barry

[A.A. Barry]

In Aus, I think, there were  spacings of 20mh with a colour for each, and then the "splits" came out later at 10mh, and a colour combining the one up and one lower, I was not $$$$s to have one, 16 at the time, still flying in circles, and for some years later. Barry 

[Chris Downing]

The RCS 10 channel Transmitter looks very similar to the Raven Electronics 10 channel system that I was given in 1972. I was a teenager at the time and my Dad thought we could get into RC flying that way. He bought a second Hand Aeronca Sedan for me (about 60" span) with the Raven Tx and RX and some Bonner Duramite and Transmite servos It used a centre-tapped NiCd pack (7.2V I think) to provide the two voltages necessary for the bi-directional servos.

The reed systems were quite fascinating in the way they worked! For the benefit of those who are not familiar with reed systems, the Transmitter sent a particular frequency, depending on the switch being held on. The receiver had a small "reed bank" to decode the channels . The reed bank looked like one of those small, clockwork, music-box devices that produce sound from a vibrating reed when the reed is 'plucked' by a rotating cylinder with protruding pins in it.
The Reed bank had ten metal reeds (one for each channel) and each reed responded to a particular frequency.

The small electromagnet in the reed bank was energised by a particular frequency, depending on the transmiter channel switch being held on, and that particular frequency caused the electromagnet to excite one matching reed, causing it to vibrate. As the reed vibrated, it made contact with a tiny, adjustable set screw. That set screw was an electric contact that connected power to one of the channel outputs, to drive a servo. Power flowed to the metal reed strips and through the set screw that was being contacted by the vibrating reed. The average "on" time of the vibrating switch was enough to keep the electronic circuit of the output held on, as long as the reed was vibrating.

I found tuning the set-screws to be a bit hit and miss but I did succeed in geting the system to work for a while. While a switch was held on, the servo would drive to the end and stay there; so to get a partial control deflection I found that you could pulse the switch on and off rapidly and the servo would hold that position.

I never flew the model like this unfortunately. I soon started to build a Microtrol Proportional 27MHz AM system, a bit at a time, from kits of parts, and using a book to learn the theory and how to assemble and test it.

I still have that Microtrol system although it has stopped working correctly.

I hope all this finds some interested ears and provokes some thought or memories!

Chris D

[David Ashby - Moderator]

Thanks Chris, really appreciate that - I've often heard the word 'reeds' used but not really known how it worked. Sounds a bit hit and miss?  

[Former Member]

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