Anybody would have few 2N4856, 2N4857 or 2N4858, and few 1 G ohm resistors ?

[gaetan8888]

Hello

Anybody would have few 2N4856, 2N4857 or 2N4858, and few 1 G ohm resistors ?

Thank you

Bye

Gaetan

 

[Enzo]

Mouser has 2N4857 in stock.


Good luck on the G-ohm resistors. WOuldn't a space of open air be about that much?

 

[PeteMcK]

re: ' 1 G ohm resistors ' - I managed to get some from RS components, might be a good source if you have a branch locally.

Building electret mic preamps?

 

[Enzo]

Actually Mouser has dozens of types of 1G resistors, I just didn;t hunt them down. They even have a 10 watt one. The largest resistor I saw there was 2.1G ohms

 

[gaetan8888]

Hello

I have myself few Brüel & Kjaer 4145 mics capsules, unpolarised capacitor mic that needed a 200V polarisation voltage, but I don't have a power supply/preamps.

So I will use this HP15118A mic preamp schematics as a preamp and a 200v voltage regulator.

condensermicpreampHP15118Amicpreamp - HostingPics.net - Hébergement d'images gratuit

Q1 1855-0020 = SFE793--2N4856 or 2N4857
Q2 1854-0307 = BCY 57/LV2345---bc109, 2n930
CR1 51.1V 5% Zener
CR2 1901-0376 = 1N3595 ----35V working 2 pF at 0V low leakage.


Thank

Bye

Gaetan

 

[gaetan8888]

Hello

Here is the schematic for the preamp and power supply for the B K 4145

Bye

Gaetan