How to measure germanium Hfe TUTORIAL!!! (pcb & spreadsheet)

Collection of answers to the basic questions of stompbox building.

How to measure germanium Hfe TUTORIAL!!! (pcb & spreadsheet)

Postby tiococo » 28 Apr 2014, 19:42

Guys, I searched a lot for something like this and it seems nobody did this for dummies. So being one myselff I decided to post something :icon_mrgreen:

First of all you here is the theory behind this:
http://www.geofex.com/Article_Folders/ffselect.htm

Here you have the pcb and layout for the circuit noted in the above link
https://mega.co.nz/#!gt5hibYI!9vbFakCUU ... rRtNXxaFEw

Download and burn. You have to hand pick a resistor that is closest to 2.2M, and with a muti turn pot, dial 2,472 (or 2,47 if your DMM goes off range)
Populate the board.

After that hook up everything as per the diagram in the first link. The board silkscreen tells you were you have to connect everything anyway :icon_biggrin:.

When your done, pinch your Germanium Tranny on the socket, paying attention to the pinout.
Set your DMM to DC Voltage in the 2v range and read the value. Write it down
Press the switch at the board. Write that down

Load that values in this spreadsheet . (idea taken from here http://www.diystompboxes.com/smfforum/i ... #msg910364)
Excel:
https://mega.co.nz/#!Jxp1DSQJ!P0kSoyHGu ... 4q9Jbjw7es

First column first reading, 2nd column 2nd reading.
The leakage current and hfe will appear at 3rd and 4th columns respectively

Thats all.

Tell me if there is any error in the steps and I'll correct it.

Regards!

For this message the author tiococo has received thanks: 3
Blitz Krieg (29 Apr 2014, 07:28), DesertCruiser (01 May 2014, 15:16), Fredenando (29 Apr 2014, 10:12)
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