Bypassing the FET inside electrec mic, not just connecting as source follower.

[ELS122]

I was thinking if it could be possible to for example put like 40-50V across the fet to short it, and then effectively connect to the electret capsule directly.
the electret element probably would be blown up in the process unless I first separate the connection between source and the case.
what do you think?

[TimFox]

Capacitor microphones, including electrets (which do not need external voltage to polarize the capacitor), can be modeled as a voltage source (from the acoustic input) in series with a not-too-huge capacitor.
To get decent response in the audio range, they require a high resistance load, in parallel with a capacitance much less than that of the microphone.
Without a JFET (or cathode follower) to buffer the actual load, the output will be disappointing.

[ELS122]

Capacitor microphones, including electrets (which do not need external voltage to polarize the capacitor), can be modeled as a voltage source (from the acoustic input) in series with a not-too-huge capacitor.
To get decent response in the audio range, they require a high resistance load, in parallel with a capacitance much less than that of the microphone.
Without a JFET (or cathode follower) to buffer the actual load, the output will be disappointing.

I don't think I posted this in the beginners tab, asking how electret mics work

[Zero999]

Why do your want one without a J-FET?

Destroying it with overvoltage is a bad idea. It's possible to remove the J-FET. I've done it before, because I wanted to try using it as an ultrasonic transducer. It didn't work too well.

[ELS122]

Why do your want one without a J-FET?

Destroying it with overvoltage is a bad idea. It's possible to remove the J-FET. I've done it before, because I wanted to try using it as an ultrasonic transducer. It didn't work too well.

but doesn't the JFET physically hold the electret mic together, and removing it would make it fall apart?
only way I could see the destroying of the fet go bad is that it goes open, or blows up which can be controlled by a current limit.

[Zero999]

Why do your want one without a J-FET?

Destroying it with overvoltage is a bad idea. It's possible to remove the J-FET. I've done it before, because I wanted to try using it as an ultrasonic transducer. It didn't work too well.

but doesn't the JFET physically hold the electret mic together, and removing it would make it fall apart?
only way I could see the destroying of the fet go bad is that it goes open, or blows up which can be controlled by a current limit.

Not in the ones I've opened. Choose the largest microphone available. Cut away at the crimping at the back and the disc at the back will fall off, along with the J-FET.

[ELS122]

I opened up 2 mic capsules I had at the time, one had the pickup plate mounted in the fet case, but it wasnt hard to just solder onto it and put it back togetger,
the other had the plate mounted in the body and the pcb made contact to the plate, also wasnt hard cutting off the fet and shorting the fet pins so it connects to the back contacts:

[Conrad Hoffman]

IMO, the best option is to just buy a decent condenser mic capsule. The prices have come down and you can get anything from a 1/4" measuring mic to a 1" studio mic. There's a group of mic builders on groups.io- https://groups.io/g/MicBuilders/messages

[Zero999]

I opened up 2 mic capsules I had at the time, one had the pickup plate mounted in the fet case, but it wasnt hard to just solder onto it and put it back togetger,
the other had the plate mounted in the body and the pcb made contact to the plate, also wasnt hard cutting off the fet and shorting the fet pins so it connects to the back contacts:
(Attachment Link)

The question is why? I hope you're aware of the fact the output impedance is very high, especially at high low frequencies. It's equivalent to around 5pF. The capacitance of a short length of cable will greatly attenuate the signal. This is why the J-FET is integrated into the microphone capsule in the first place.

In my case, I removed the J-FET so I could connect it to an oscillator to generate ultrasound. It didn't work very will. I'd probably need to run it at a couple of hundred volts peak, to generate a decent output, which I didn't try, as it would've probably smoked.

[ELS122]

IMO, the best option is to just buy a decent condenser mic capsule. The prices have come down and you can get anything from a 1/4" measuring mic to a 1" studio mic. There's a group of mic builders on groups.io- https://groups.io/g/MicBuilders/messages

yes I know.

I opened up 2 mic capsules I had at the time, one had the pickup plate mounted in the fet case, but it wasnt hard to just solder onto it and put it back togetger,
the other had the plate mounted in the body and the pcb made contact to the plate, also wasnt hard cutting off the fet and shorting the fet pins so it connects to the back contacts:
(Attachment Link)

The question is why? I hope you're aware of the fact the output impedance is very high, especially at high frequencies. It's equivalent to around 5pF. The capacitance of a short length of cable will greatly attenuate the signal. This is why the J-FET is integrated into the microphone capsule in the first place.

In my case, I removed the J-FET so I could connect it to an oscillator to generate ultrasound. It didn't work very will. I'd probably need to run it at a couple of hundred volts peak, to generate a decent output, which I didn't try, as it would've probably smoked.

for curiosity.
wondered what would happen if I biased the capsule externally, biased it to around 100V and it had slightly more gain but nothing much, could also be that the removal of the FET wired as a source follower was why I got more gain after removing it and applying external DC bias

[Zero999]

IMO, the best option is to just buy a decent condenser mic capsule. The prices have come down and you can get anything from a 1/4" measuring mic to a 1" studio mic. There's a group of mic builders on groups.io- https://groups.io/g/MicBuilders/messages

yes I know.

I opened up 2 mic capsules I had at the time, one had the pickup plate mounted in the fet case, but it wasnt hard to just solder onto it and put it back togetger,
the other had the plate mounted in the body and the pcb made contact to the plate, also wasnt hard cutting off the fet and shorting the fet pins so it connects to the back contacts:
(Attachment Link)

The question is why? I hope you're aware of the fact the output impedance is very high, especially at high frequencies. It's equivalent to around 5pF. The capacitance of a short length of cable will greatly attenuate the signal. This is why the J-FET is integrated into the microphone capsule in the first place.

In my case, I removed the J-FET so I could connect it to an oscillator to generate ultrasound. It didn't work very will. I'd probably need to run it at a couple of hundred volts peak, to generate a decent output, which I didn't try, as it would've probably smoked.

for curiosity.
wondered what would happen if I biased the capsule externally, biased it to around 100V and it had slightly more gain but nothing much, could also be that the removal of the FET wired as a source follower was why I got more gain after removing it and applying external DC bias

The FET is common source. It is not a follower.

An electret is the electrostatic equivalent of a permanent magnet. The whole point of using an electrect microphone is there's no need for a high voltage power supply to bias it. The principle is similar to using a permanent magnet in a dynamic microphone, rather than an electromagnet.

[ELS122]

IMO, the best option is to just buy a decent condenser mic capsule. The prices have come down and you can get anything from a 1/4" measuring mic to a 1" studio mic. There's a group of mic builders on groups.io- https://groups.io/g/MicBuilders/messages

yes I know.

I opened up 2 mic capsules I had at the time, one had the pickup plate mounted in the fet case, but it wasnt hard to just solder onto it and put it back togetger,
the other had the plate mounted in the body and the pcb made contact to the plate, also wasnt hard cutting off the fet and shorting the fet pins so it connects to the back contacts:
(Attachment Link)

The question is why? I hope you're aware of the fact the output impedance is very high, especially at high frequencies. It's equivalent to around 5pF. The capacitance of a short length of cable will greatly attenuate the signal. This is why the J-FET is integrated into the microphone capsule in the first place.

In my case, I removed the J-FET so I could connect it to an oscillator to generate ultrasound. It didn't work very will. I'd probably need to run it at a couple of hundred volts peak, to generate a decent output, which I didn't try, as it would've probably smoked.

for curiosity.
wondered what would happen if I biased the capsule externally, biased it to around 100V and it had slightly more gain but nothing much, could also be that the removal of the FET wired as a source follower was why I got more gain after removing it and applying external DC bias

The FET is common source. It is not a follower.

An electret is the electrostatic equivalent of a permanent magnet. The whole point of using an electrect microphone is there's no need for a high voltage power supply to bias it. The principle is similar to using a permanent magnet in a dynamic microphone, rather than an electromagnet.

depends on the circuit.
many electret mics have 3 connections so you can wire them up however you want to, and if not you can easily modify them by cutting the trace on the PCB