# Simulcast and the oc71 transistor



## Crookedtooth

Having trouble finding this part for the Simulcast. Does anybody have any links or suggestions? Thanks!


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## Nostradoomus

Any PNP Germanium with an Hfe rating of 70-120 should work fine


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## K Pedals

Crookedtooth said:


> Having trouble finding this part for the Simulcast. Does anybody have any links or suggestions? Thanks!


I got mine here  it took awhile to get here but they work good... 








						10pcs TG5S = OC71 Germanium PNP transistor 30V 10mA 75mW 1MHz - Made in Poland  | eBay
					

Polish equivalent of OC71, AC122 etc. 30V  10mA  75mW  1MHz. Made in Poland. Manufacturer: UNITRA CEMI Warsaw in 1976.



					rover.ebay.com


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## Jovi Bon Kenobi

Smallbear also has them but they are $10 for one. 








						Transistor - The Rangemaster Newmarket OC71
					






					smallbear-electronics.mybigcommerce.com


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## HamishR

Have to agree with Nostradoomus.  Having built plenty of pedals with Ge transistors, both pricey and cheap, I have come to the conclusion that there is not a great deal of difference in the types of Ge trannies. Maybe there is in some circuits but if you're just using them to go grrrrr then I don't hear it!  I've had great results with inexpensive Russian Ge transistors bought off Ebay.  Hardest bit is finding higher hfe with low leakage, but it can be done.  If anything I've had better luck with the Russian Ges than with the more expensive western Euro or US trannies, possibly because the good ones have already been taken.


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## TheSin

Crookedtooth said:


> Having trouble finding this part for the Simulcast. Does anybody have any links or suggestions? Thanks!


Hey there, so what transistor did you use? I am having the same issue finding what’s recommended.


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## cooder

I have just built one and used an AC128 with 80 Hfe and that sounds fine to me, not that I have auditioned others. FWIW.


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## frankenteletron

I found one here last week. https://tubedepot.com/products/oc71-cv5712-mullard-uk-germanium-transistor


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## TheSin

K Pedals said:


> I got mine here  it took awhile to get here but they work good...
> 
> 
> 
> 
> 
> 
> 
> 
> 10pcs TG5S = OC71 Germanium PNP transistor 30V 10mA 75mW 1MHz - Made in Poland  | eBay
> 
> 
> Polish equivalent of OC71, AC122 etc. 30V  10mA  75mW  1MHz. Made in Poland. Manufacturer: UNITRA CEMI Warsaw in 1976.
> 
> 
> 
> rover.ebay.com


I see these on ebay. Any issues with them and d


K Pedals said:


> I got mine here  it took awhile to get here but they work good...
> 
> 
> 
> 
> 
> 
> 
> 
> 10pcs TG5S = OC71 Germanium PNP transistor 30V 10mA 75mW 1MHz - Made in Poland  | eBay
> 
> 
> Polish equivalent of OC71, AC122 etc. 30V  10mA  75mW  1MHz. Made in Poland. Manufacturer: UNITRA CEMI Warsaw in 1976.
> 
> 
> 
> rover.ebay.com



Just ordered a batch of these....fingers crossed that they are ok and within proper gain tolerance


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## K Pedals

TheSin said:


> I see these on ebay. Any issues with them and d
> 
> 
> Just ordered a batch of these....fingers crossed that they are ok and within proper gain tolerance


If I remember right at least 5 out of the 10 were in spec for the simulcast...


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## TheSin

K Pedals said:


> If I remember right at least 5 out of the 10 were in spec for the simulcast...


Nice, I can possibly build 5 of these bad boys then. Thanks!
[/QUOTE]


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## TheSin

K Pedals said:


> If I remember right at least 5 out of the 10 were in spec for the simulcast...



I just received my batch of these. Looks like around 5 of them measured in the 70-90 gain range, leakage within tolerance. I used Small Bear’s measuring technique. I haven’t built the pedal yet though. Thanks for the suggestion


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## ntuncer

Nostradoomus said:


> Any PNP Germanium with an Hfe rating of 70-120 should work fine


Hello @Nostradoomus, I plan to buy a tested AC125 transistor. Is it better to choose hfe=70-80 or hfe=110-120 to suit better this pedal? Thanks in advance!


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## temol

I have some TG5S transistors mentioned above. I've measured maybe 50 pieces. They rarely go above 90 hfe.  Most of the measured pieces fall between 50-70. At least in my batch.


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## Teddeeh

K Pedals said:


> I got mine here  it took awhile to get here but they work good...
> 
> 
> 
> 
> 
> 
> 
> 
> 10pcs TG5S = OC71 Germanium PNP transistor 30V 10mA 75mW 1MHz - Made in Poland  | eBay
> 
> 
> Polish equivalent of OC71, AC122 etc. 30V  10mA  75mW  1MHz. Made in Poland. Manufacturer: UNITRA CEMI Warsaw in 1976.
> 
> 
> 
> rover.ebay.com


Yes, ive used these for a couple of years now from a reccomendation from TX pedals (animallizzer pedal)


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