# Duocast Transistor



## Knotty Pine (Jun 8, 2020)

Hey gang! I just ordered a Duocast PCB and I am super pumped! As I am sourcing parts I am having a hard time finding an OC71 - However I have a random assortment of Ge transistors from 3pdt. Is there a way to socket Q2 so can experiment with different transistors? Like, should I just solder individual pins from a sip socket?  According to a few builders having a Ge transistor with an hFE around 80 seems to be ideal. Thanks for any and all information you can provide.


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## manfesto (Jun 9, 2020)

I just chop these up into individual sockets









						40 Pin 2.54mm DIP SIP IC Sockets Adaptor Solder Type
					

Lead Free - Get It Fast - Same Day Shipping




					www.taydaelectronics.com


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## K Pedals (Jun 9, 2020)

manfesto said:


> I just chop these up into individual sockets
> 
> 
> 
> ...


Yeah I think on this one you can leave two together and then just solder another separate one... it’s a little bit easier...


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## K Pedals (Jun 9, 2020)

Knotty Pine said:


> Hey gang! I just ordered a Duocast PCB and I am super pumped! As I am sourcing parts I am having a hard time finding an OC71 - However I have a random assortment of Ge transistors from 3pdt. Is there a way to socket Q2 so can experiment with different transistors? Like, should I just solder individual pins from a sip socket?  According to a few builders having a Ge transistor with an hFE around 80 seems to be ideal. Thanks for any and all information you can provide.


the new ones made by Hudson are using Russian transistors...I think they’re mp20...


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## Knotty Pine (Jun 9, 2020)

K Pedals said:


> the new ones made by Hudson are using Russian transistors...I think they’re mp20...


Awesome! Thanks for the help K! I just put an order in for some MP20’s and some MP21A’s


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## Allthumbs (Jun 9, 2020)

OC71 / CV5712 Mullard UK Germanium Transistor
					

Great for your Rangemaster clone and other fuzzbox / distortion projects, these Mullard made OC71 / CV5712 germanium transistors are getting harder and harder to find.




					www.tubedepot.com


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## Nostradoomus (Jun 9, 2020)

This kind of socket is really what you want. I’ve noticed plenty of old germaniums don’t quite fit into SIP sockets (enough to test, but nothing I’d leave in for good). Search around for To-5 3 position sockets.


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## Knotty Pine (Jun 9, 2020)

Nostradoomus said:


> View attachment 4848
> This kind of socket is really what you want. I’ve noticed plenty of old germaniums don’t quite fit into SIP sockets (enough to test, but nothing I’d leave in for good). Search around for To-5 3 position sockets.


Sweet! Thanks for the heads up


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## Betty Wont (Jun 9, 2020)

Russian ge transistors can easily be had for 25 cents each. They seem to have a much higher usability rate than euro and US transistors. Out of the last three lots of a hundred Russians I bought only ONE piece didn't work. The market of euro and US ge transistors today is almost entirely culls. Unscrupulous dealers sell "untested" ones for up to $10 each just because the same badge may have been used in a beloved vintage effect. Electrons don't care about the branding.


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## joelorigo (Jun 9, 2020)

I am intere


Torgoslayer said:


> Russian ge transistors can easily be had for 25 cents each.



Where are you buying them?


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## Knotty Pine (Jun 9, 2020)

joelorigo said:


> I am intere
> 
> 
> Where are you buying them?


eBay 






						Security Measure
					






					ebay.com
				




MP20

https://ebay.com/usr/bg2014-manue 

I bought out the last of that sellers MP21A but there are others to be had.


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## joelorigo (Jun 9, 2020)

Knotty Pine said:


> eBay



Thanks! 

Then I would have to get a tester as well. Can anyone recommend one?


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## Knotty Pine (Jun 9, 2020)

joelorigo said:


> Then I would have to get a tester as well. Can anyone recommend one?


I need one too! ?


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## Nostradoomus (Jun 9, 2020)

Peak DCA55 or 75. I have a DCA55 and it does the job for selecting GE transistors quite well.


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## Knotty Pine (Jun 10, 2020)

Nostradoomus said:


> Peak DCA55 or 75. I have a DCA55 and it does the job for selecting GE transistors quite well.


Thank you for your recommendation!
I got a DCA55 and some sockets coming from Digi-Key, I think that I am all set.


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## joelorigo (Jun 10, 2020)

Thank you also


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## spexicola (Jun 11, 2020)

Here's a pack of GT308B which I picked up for some upcoming projects, as an example. The packaging is really fun.


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## TheSin (Jun 14, 2020)

Knotty Pine said:


> Awesome! Thanks for the help K! I just put an order in for some MP20’s and some MP21A’s


Which one did you like best?


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## Knotty Pine (Jun 14, 2020)

TheSin said:


> Which one did you like best?


I didn’t end up with any of the transistors because my orders were cancelled/refunded due to int’l shipping restrictions (Bulgaria, Russia) from Covid. I ended up using an oddball Chinese transistor (3AG1D) with an hFE of 85 that sounds pretty good. Gonna dial in the gain trimmers today


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