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Author Topic: 3-Transistor Composite Mod - Transistor question  (Read 167 times)
Xuul
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« on: June 06, 2022, 12:31:13 AM »

Hi guys,

I've been modding a lot of Videopac G7000's lately ( 2-Transistor composite mod, power switch, LED, PSU replacement... ), and I want to step it up a notch and replace the 2-transistor-mod with this 3-transistor-mod:
https://gamesx.com/wiki/doku.php?id=av:g7000_av

I'm currently putting the shopping-list together. The thing is, I need 2x BC548 and 1x BC558. Both come in different variations ( BC548, BC548A, BC548B, BC548C / BC558, BC558A, BC558B, BC558C ).
There are differences in the current gain, feedback ratio etc. Here's the datasheet with all variations: https://cdn-reichelt.de/documents/datenblatt/A100/BC546_48-CDIL.pdf

The question is, which one should I use to get the best signal possible? Has anyone ever built this circuit?  Huh?
I could order all variations and probe the signal with an oscilloscope, but I'd prefer some solid experience from you guys  Kiss

Thanks,
Xuul


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Xuul
Trying to get the cartridge in...
*
Posts: 3


READY PLAYER ONE


PSYLABS PSYLABS
WWW
« Reply #1 on: June 10, 2022, 04:47:08 AM »

After talking to René, I ordered the C-variations.
It shouldn't make a difference whether you use the B or the C variant, as the amount of gain is not too critical a factor.
I still have some B-types at home, so I'll do some tests with the different variants to see if there's a discernible difference.

Cheers  Smiley
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