09-11-2023, 12:19 PM
(This post was last modified: 09-11-2023, 12:22 PM by Mike Watterson.)
I've a pair of cardiod Electret mics.
Electret capsule is earthed and on a rubber mount. Two wires from the capsule unit to body via centre of rubber mount with on/off switch and battery negative spring. No other parts in body. The red wire to on/off than it goes to presumed negative end of battery (spring terminal in body). Black to casing at switch.
The end cap has contact for battery plus which goes to the signal/centre of coax cable. The outer is connected to body of screw on cap. The signal plug end to contact on cap is zero ohms, 0 Ω. The resistance centre of cap to outer (or plug end of cable) is about 690 Ohms. I guess a 680 Ohm resistor.
Is this a cunning scheme to avoid having a series capacitor?
How might FET (presumably inside metal capsule) and capsule be wired? The black wire is earthed where on/off switch connects to case. Surely the red has -Ve and black has +ve?
Or should top of battery go to spring and -ve to spud on screw on cap? It does work with battery negative to spring
Model is Altai EM-512
Perhaps not quite vintage, but maybe over 25 years old.
Electret capsule is earthed and on a rubber mount. Two wires from the capsule unit to body via centre of rubber mount with on/off switch and battery negative spring. No other parts in body. The red wire to on/off than it goes to presumed negative end of battery (spring terminal in body). Black to casing at switch.
The end cap has contact for battery plus which goes to the signal/centre of coax cable. The outer is connected to body of screw on cap. The signal plug end to contact on cap is zero ohms, 0 Ω. The resistance centre of cap to outer (or plug end of cable) is about 690 Ohms. I guess a 680 Ohm resistor.
Is this a cunning scheme to avoid having a series capacitor?
How might FET (presumably inside metal capsule) and capsule be wired? The black wire is earthed where on/off switch connects to case. Surely the red has -Ve and black has +ve?
Or should top of battery go to spring and -ve to spud on screw on cap? It does work with battery negative to spring
Model is Altai EM-512
Perhaps not quite vintage, but maybe over 25 years old.
