EHX - Germanium OD

flood · Post by **flood** » 29 Aug 2009, 06:32

sorry, i can't edit anymore, hence the second post - i'm thinking of the mullard black glass 0c141 in particular. how much would i need to modify the values of say a PNP OC81 tonebender to get similar results with negative ground and OC141?

RnFR · Post by **RnFR** » 29 Aug 2009, 06:43

the bias techniques are the same, but the normal npn to pnp rules still of course apply.

flood · Post by **flood** » 29 Aug 2009, 06:53

RnFR wrote:the normal npn to pnp rules still of course apply.

ah ok... i'm assuming that by that you simply mean changing the polarity of electrolytics and diodes?

thanks again.

flood · Post by **flood** » 01 Sep 2009, 05:21

ok, i was a bit overconfident so i went right ahead and built a prototype on perf. doesn't work. here's alink to the new thread i opened: https://www.freestompboxes.org/viewtopic.php?f=10&t=7183

SD456 · Post by **SD456** » 07 Aug 2010, 14:12

Hi all!

Someone please upload the EHX Germanium OD schematics, the links are not working in the first post

Thanks in advance!
Sorry for my English!

Broadcaster · Post by **Broadcaster** » 07 Aug 2010, 14:37

Well, hi SD456 - welcome and all that BUT... don't you think is leaves not the best impression when your first post shows you were not willing/able to read the discussion with all its deviations about this very subject? Also, you surely know the difference between a gutshot and a schematic?!
Really guys / gals - this is a happy and helpful bunch of people here (well, usually), but requests of that kind will not lead anywhere... but we all applaud if you will actively participate.

diodead · Post by **diodead** » 08 Aug 2010, 23:15

Broadcaster wrote:Well, hi SD456 - welcome and all that BUT... don't you think is leaves not the best impression when your first post shows you were not willing/able to read the discussion with all its deviations about this very subject? Also, you surely know the difference between a gutshot and a schematic?!
Really guys / gals - this is a happy and helpful bunch of people here (well, usually), but requests of that kind will not lead anywhere... but we all applaud if you will actively participate.

I can respect that, totally. And I don't know shit about shit.

mirosol · Post by **mirosol** » 15 Sep 2014, 19:38

Got mine in the mail today and checked it out. Couple of bad photos and a trace are attached.

After the initial trace, my drawing of the design didn't make much sense. No matter how many times i checked and rechecked everything. So i decided to breadboard the circuit before posting the drawing anywhere. Spotted one small error on the breadboard and fixed it on the schematic too. I used 470n mylars for caps and 2N3906s for all three transistors on that breadboard setup. Works. And sounds very close to the original unit. Maybe even better with 2N3906 instead of "NKT275". Can't help but ask - have any of you seen a design like this before? I sure haven't...

Just realized i forgot to mark which way the pots turn.. All three are CW towards south.

Nocentelli · Post by **Nocentelli** » 15 Sep 2014, 20:23

Looks like a buffered rangemaster upside down.

mirosol · Post by **mirosol** » 15 Sep 2014, 20:39

Nocentelli wrote:Looks like a buffered rangemaster upside down.

Yes. I flipped it around to see if it made more sense like that, but no. I wouldn't call that a Rangemaster - even though there are some similarities.
+m

EHX - Germanium OD [schematic]