diode switching

Ken Stone sasami at blaze.net.au
Fri May 1 07:49:37 CEST 1998

The diode switching I have seen was fairly simple in operation.

In the most basic (simplified) system, the outputs of the top octave
synthesizer and octave dividers were fed to the cathodes of a lot of diodes
- one per key. the other end of these diodes were connected via a resistor
to a common "mixer bus", effectively being pulled low. No signal passed
through the diodes, because the anode was being held at a voltage equal to
or lower than the cathode.

Now when a key was pressed another resistor, connected at one end through
the key to a positive supply, now applied a potential to the junction of the
anode of the diode and the mixer resistor, pulling this juntion high when
the signal on the cathode of the diode was high (and being pulled low via
the diode when the cathode was low), thus, allowing the wave present at the
cathode of the diode to pass onto the mixer bus.


>meo wrote:
>> Anyone know the details on diode switching? I have an old ww2 era b1
>> bomber communications rack that appears to use diode switching in the
>> audio range to switch 25 inputs and outputs to transmit or recieve via
>> 3-way toggles. I always wanted to do this but couldn't find info. Any
>> one with experience?                Michael reslabs at airmail.net
>A lot of the early home organs used diode switching - ones
>that I know of included Elka, and the first few Hammonds that
>actually had solid state instead of valves...
>I know it's not much, but it might provide a lead on tracking
>down a circuit or two.
>Merlin Zener                            mailto:merlin at ion.com.au
>Piano and Synthesizer               voice: (+61) (0) 418 779 594
>Gold Coast, Australia              http://www.ion.com.au/~merlin
>"No-one ever went blind from looking on the bright side of life"

                Ken Stone  sasami at blaze.net.au
                   ** Catgirl Paradise **
         ** Australian Miniature Horses and ponies **

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