# NPN in the Sunflower Fuzz



## uberjohn (May 24, 2019)

I would like to use the sunflower PCB with BC109 NPN transistors.  What changes are required?

Obvious changes:
- No need for a -9V generator, use +9V from SW instead
- polarized caps need to be reversed
- no sundial needed

Am I missing anything?


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## Robert (May 24, 2019)

Omit C5 and IC1
Install jumper from Pin 8 to Pin 5 of unpopulated IC1 (this will give you a +9V rail, no need to fool with SW)
Reverse all remaining electrolytics
Install jumper across pads 1 and 2 of Sundial control.
Ensure pinouts of Q1 and Q2 are correct


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## estimated_eyes (Jun 2, 2020)

@PedalPCB 

Is the sundial pot omitted when doing this build, putting the jumper on the board? Or is the jumper from pad 1-2 done on the pot?


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## uberjohn (Jun 4, 2020)

Short answer: 

Omit Sundial pot
Install wire jumper across pads 1 and 2 of Sundial control 

Long answer:

The Sundial is nearly a necessity on vintage PNP transistors, because Germanium transistors vary widely in gain with small changes in temperature.  The Sundial is only somewhat useful on Silicon (NPN) transistors in order to tweak the tone of the fuzz, because Silicon transistor gain is far less sensitive to temperature changes.  No sundial means one less hole in your enclosure, and one less knob to worry about getting bumped out of adjustment or damaged.  Also, pots are relatively expensive compared to a 5 cent resistor or a 1 cent wire jumper.

On a related note, the FuzzFace circuit gain partially depends on the internal resistance of the battery!  A 9V Carbon-Zinc battery has about 35-50 ohms of internal resistance.  I'm considering just using a pair of 9V adapters with a 100 ohm trimmer pot in series, to use with 9V Lithium Ion rechargeables, which have a very low internal resistance.  Down the road I could build a +9V internal supply and run the pedal off standard Boss style negative-tip power, and add a 35-40 ohm series resistor (1/2 watt should be fine.)  Might even splurge on carbon film .


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## estimated_eyes (Jun 5, 2020)

Thanks @uberjohn !

As this entire build has been a learning process in more ways than one, I already drilled the enclosure for a third pot ?‍♂️

I have the pot on hand so at this point I'm open to going either way with it, I certainly don't need to use it on this build.

I was reading that adding the Sundial control may possibly introduce a lot of noise into the circuit when doing this build with silicon transistors?

As I am still learning much about circuitry, I am a bit confused on what you are explaining with the battery internal resistance? My understanding is that the adjustments mentioned above by PedalPCB allow this pedal to be powered by Boss style negative-tip power?

Also, how did your build end up going for this circuit!? How's it sounding?


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