21-01-2023, 06:43 PM
A selection of key contacts and relays for electrostatic organs.
Key contacts and busbars
* 10-pole silver DC keying (Compton 357)
* Conductive plastic audio keying (Parie)
Compton key relays
* 13-pole (Draper) from both contact and wiring sides
* 21-pole (365) from both contact and wiring sides
Note that on these DC-keyed electrostatic instruments there is an isolating resistor at every key contact, sometimes also an earth resistor. This means that up to 5,000 resistors are embedded in the structure of the relay, one end soldered to the contact and intricate diagonal crosswiring on the other. They are high values and at risk of serious upward drift. This is one reason that I study the behaviour of carbon composition resistors closely. One does not want to change 100,000 resistors (approx total in the collection) if it's not necessary.
Key contacts and busbars
* 10-pole silver DC keying (Compton 357)
* Conductive plastic audio keying (Parie)
Compton key relays
* 13-pole (Draper) from both contact and wiring sides
* 21-pole (365) from both contact and wiring sides
Note that on these DC-keyed electrostatic instruments there is an isolating resistor at every key contact, sometimes also an earth resistor. This means that up to 5,000 resistors are embedded in the structure of the relay, one end soldered to the contact and intricate diagonal crosswiring on the other. They are high values and at risk of serious upward drift. This is one reason that I study the behaviour of carbon composition resistors closely. One does not want to change 100,000 resistors (approx total in the collection) if it's not necessary.
