# Buzz Aldrin - BC109 vs BC109C vs BC549(C)?



## MattG (Oct 12, 2021)

Looking at the Fuzz Aldrin, the documentation says BC109 transistors.  Looking at @Chuck D. Bones guide to Lunar Module / Screw Driver / Hybrid Fuzz Drive modifications, BC109*C* is listed.  Does it matter which is used?

Also, the modicum of web searching I did suggests that BC549 is a modern equivalent (read: readily available, cheap) replacement for BC109.  Would that work as well in these circuits?

While I'm at it, Chuck also suggested AC127 for the germanium transistor.  Small Bear has these... at $4 a pop!  Is there a modern equivalent or "close enough" part that will work here?


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## Coda (Oct 12, 2021)

When I look at the Fuzz Aldrin build doc, it states BC109C. I don’t know if it’s just me, though…

Also, $4 each for AC127 isn’t a bad deal. If you use sockets you can try all sorts of things in the pedal…


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## Barry (Oct 12, 2021)

MattG said:


> Looking at the Fuzz Aldrin, the documentation says BC109 transistors.  Looking at @Chuck D. Bones guide to Lunar Module / Screw Driver / Hybrid Fuzz Drive modifications, BC109*C* is listed.  Does it matter which is used?
> 
> Also, the modicum of web searching I did suggests that BC549 is a modern equivalent (read: readily available, cheap) replacement for BC109.  Would that work as well in these circuits?
> 
> While I'm at it, Chuck also suggested AC127 for the germanium transistor.  Small Bear has these... at $4 a pop!  Is there a modern equivalent or "close enough" part that will work here?


That C denotes higher gain as I recall, that would hold true on the 109 or 549, A and B lower gain, no ABC not rated could be anything


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## jeffwhitfield (Oct 12, 2021)

Amplified Parts has the BC109C's for $.99 a piece. Not a bad price. 






						Transistor - BC109, TO-18 case, NPN | Amplified Parts
					

BC109 NPN silicon transistors. The BC109 is a popular NPN choice for fuzz pedals and other effects such as vintage silicon Fuzz Face builds and Big Muff clones. Type hFE (IC=2mA, VCE=5V) hfe (IC=2mA, VCE=5V, f=1KHz) BC109B 200-450 240-500 BC109C 420-800 450-900




					www.amplifiedparts.com
				




Pedal Parts and Kits has a sale on 10-packs for $8.50:









						BC109C Transistors - 10 Pack
					

These transistors are getting a little harder to find, and a little more expensive, but we've recently found a decent source and can offer these at a price lower than our competitors. This particular NPN silicon transistor is used in the DSOTM fuzz, the Color Tone Overdrive, and others. Gain is...




					www.pedalpartsandkits.com


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## MattG (Oct 13, 2021)

Coda said:


> When I look at the Fuzz Aldrin build doc, it states BC109C. I don’t know if it’s just me, though…



🤦‍♂️ Ugh, well, there goes my dignity!  Yes, you're absolutely right, the doc plainly says BC109C.  I don't know where I got it in my head that it didn't have the "C".  (And what's thoroughly embarrassing is that I took the time to link the product page---one more click and I could have easily reviewed the doc!)





jeffwhitfield said:


> Amplified Parts has the BC109C's for $.99 a piece. Not a bad price.
> 
> 
> 
> ...



Thanks for that!  I think I'll probably pick up a few!


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## thesmokingman (Oct 13, 2021)

it is important to note that the source of the transistor also plays a part ... most available BC109C are coming from CDIL in India ... and there are the older ones that have the proper gain range then there's the newer ones where the gain range is 800+ 

there are a number of BC109C available from smallbear with the proper gain ranges including CDIL but smallbear does sort their CDIL into two listings, the high gain and the normal gain


to be honest any silicon in the gain range of 500-600 should be fine, designating a specific transistor is so you hit the right gain bucket


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## mdc (Oct 13, 2021)

I would just use the BC549C, AFAIK it's literally the same device with identical specs with lower noise at a fraction of the price. 
That said, metal cans are dope.


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## Coda (Oct 13, 2021)

thesmokingman said:


> it is important to note that the source of the transistor also plays a part ... most available BC109C are coming from CDIL in India ... and there are the older ones that have the proper gain range then there's the newer ones where the gain range is 800+
> 
> there are a number of BC109C available from smallbear with the proper gain ranges including CDIL but smallbear does sort their CDIL into two listings, the high gain and the normal gain
> 
> ...


My latest batch of CDIL 109C’s were all lower to medium range. I also got some newer 108’s, and one of them measure 820hfe!


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## mdc (Oct 13, 2021)

Also, FWIW I built a lunar module on vero a while ago and used randomly-picked BC549C and it sounds great.


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## finebyfine (Oct 14, 2021)

to add to the chorus: I’ve substituted bc549cs several times and would do it again without a second’s thought. Any similar Hfe range low noise NPN should get you close, MPSA18, 2sc1815, etc.


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## HamishR (Oct 14, 2021)

I guess it's because the original Lunar Module was built with BC109Cs that they are the spec. I have used BC549Cs and they've sounded much the same. They are the same transistor spec but updated for the plastic housing and lower noise, as pointed out above. BC109Bs won't have the right hfe. You could probably use something like a 2N5088 with good results but mind the pinout.


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