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DIY Guitar Pedals 7 Min Fuzz, Manual

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DIY Guitar Pedals 7 Min Fuzz Manual Download Page 1

 

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www.diyguitarpedals.com.au 

 

 

7 Min Fuzz 

The 7 min fuzz is a low part count high-gain circuit that produces a very respectable, thick sounding fuzz tone.  However 
this is just one of the sounds capable from this circuit. It is quite adaptable and if you have purchased the experimenters 
kit you can follow along with my basic notes on how to tweak it!  The BOM below lists the ‘standard’ configuration (thick 
sounding fuzz). 
 

Bill of Materials 

Resistors 

Diode 

R1

 

                10k               

D1

                        BAT41         

       

 

 

Capacitors 

Transistor 

C1  

                 

1uf (105)      

 

Q1 

 

 

MPSA13            

 

C2  

                 

100nf (104)   

 

 

Potentiometer 

 

Volume               

100ka Log            

 

Summary of Contents for 7 Min Fuzz

Page 1: ...e of the sounds capable from this circuit It is quite adaptable and if you have purchased the experimenters kit you can follow along with my basic notes on how to tweak it The BOM below lists the standard configuration thick sounding fuzz Bill of Materials Resistors Diode R1 10k D1 BAT41 Capacitors Transistor C1 1uf 105 Q1 MPSA13 C2 100nf 104 Potentiometer Volume 100ka Log ...

Page 2: ...2 www diyguitarpedals com au ...

Page 3: ...of the transistor Orientation of the resistor and capacitors The resistors and capacitors film are not polarized and can be inserted into the circuit board either way Reference Designators The reference designator the letter followed by a number found on the bill of materials see picture below identifies the component of an electrical schematic This Reference Designator refdes for short also appea...

Page 4: ...C1 and C2 available on the webstore Film capacitors in values above 1uf are quite expensive so it s typical to use electrolytic ones in their place Electrolytic capacitors in values between 1uf and 10uf would be suitable for experimentation Electrolytic capacitors are polarized one lead is negative the other positive The positive lead should be connected to the more positive side of the circuit Th...

Page 5: ...fication for adjusting the gain of the effect by adding a potentiometer to the circuit a device that increases resistance as you turn the dial Check out the wiring diagram below for a visual representation of how to go about adding this gain control and also my video on how to add a Gain control the 7 min fuzz circuit YouTube link https www youtube com watch v WCFrhkL1a2I ...

Page 6: ...6 www diyguitarpedals com au Tip for soldering 9mm Alpha Pots ...

Page 7: ...om au Note you can still test your effect with 2 mono jacks just combine the negative of the battery with the ground input sleeve connection A DC Jack will also work for a power source replace the battery above with a dc jack ...

Page 8: ...will note it physically has a flat side This is the negative side of the led as pictured above The Lugs of the Miniature DC Jack The miniature dc jacks that are sold as a kit option with PCBs have 2 lugs 1 short and 1 long and should be connected as shown in the picture to the right To confirm which lug is which sight done the socket hole you should be able to see which lug is connected to the pin...

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Page 11: ...ring a recovery stage at the end The circuit is designed around a single NPN bi polar junction transistor BJT or Darlington Pair transistor 2 BJTs butted together into one transistor package with maximum gain applied to its emitter pin which is grounded The single diode uses its voltage drop to bias the base of the transistor below the collector voltage which also provides asymmetrical soft clippi...

Page 12: ...ircuit The Q1 transistor just needs to be high gain hFE of 5 000 minimum per the MPSA13 datasheet The lower the hFE value on the selected Q1 transistor the less saturation and fuzz will occur and the higher the hFE value more saturation and fuzz Example transistors that could be used Transistor hFE min VCE 5 0V IC 1 0mA MPSA14 10 000 MPSA13 5 000 MPSA18 500 2N5089 400 2N5088 300 2N5210 250 2N3904 ...

Page 13: ...ences the bias Installing a potentiometer 250ka or so with pins 1 and 2 replacing the R1 pads and playing around with it should be interesting and possibly enlightening as this could be used to fine tune the Vc Vb This trick works fine with germanium transistors and diodes but you have to adjust constantly because temperature and leakage are a nightmare Not a must with silicon transistors and diod...

Page 14: ...nerally though you can assume that larger capacitance values for C1 like 10uF will drop the frequency cut point to a lower frequency allowing more bass to come through Dropping the capacitance values to 10nF will raise the frequency cut point to a higher frequency cutting out more bass frequencies from coming through 3 2 Emitter Resistance and Input Impedance As covered in the Gain Control Mod sec...

Page 15: ...filter changes frequency position For example if the pot is half way fc 1 2π 50K 100nF fc 1 2π 50 000 0 0000001 fc 32Hz So now some of the sub bass frequencies will begin to get cut A way to resolve this is to increase capacitance of C2 to a 1uF electrolytic or film capacitor 4 1 Output Impedance The pedal output impedance also depends on the volume potentiometer position being always less than th...

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