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How can I make a guitar fuzz effect


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Fuzz is just a VERY BAD amp. The classic sound is the Jimmy Hendrix sound.
I attached the circuit that makes that sound when driven by the right pickups.
I am not sure what pickups he used.  I am guessing they were just stratocaster single coil pickups.  Humbuckers came along later.

If you are getting clean sound or a very weak effect your pickups might be too weak.  If you can't afford new pickups try heavy strings for slightly more output.

You can also add a pre-amp on the front of the FUZZ circuit (A fet input Op_amp would be enough) 

can you send the circuit you were using along with what it was doing. Maybe you already have one built and just have a component in wrong. 

-Mike

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Your circuit is set up as a inverting Op-Amp with Clipping.
The first part of the circuit is the two 100k resistors,
They form a Virtual Ground for the OpAmp.
The 741 is designed to run on a dual supply. By
Cutting the 9v in half, the 4.5v that appears at pin 3
Appears to be the ground for the amp.

I am not sure what the purpose of the 100uF cap on
The low side of the divider is.  It may have been intended
To filter out noise and keep the ground steady.  In truth,
As the current is drawn from the battery the source voltage will
Drop and the 4.5v will drop also.  If the battery gets low, sudden
Current drains could cause the Virtual ground to fall BELOW
The stored voltage of the 100uf Cap.  As the input resistance
Of the 741 is nearly 20M, it is likely the entire circuit could
Shift sound as the battery goes dead.  I’d drop that part for now.

The next part of the circuit is the feedback loop.
Without the diodes the feedback is (1M / 1K) or  X1000
The 1N4001 diodes then short out that formula at any
Voltage above 1 volt.  (Under 1 volt the diodes tend to
Act like resistors – Look up ‘Knee Voltage’)
That means that any input signal will be allowed to see normal
Amplification unless the output exceeds 1V Pos or Neg.

The remaining capacitors are just DC blocking. They let the Audio
Signal through while blocking any stray DC between the guitar, The effect and the Amp.

My first test would be to check for 4.5V at pin 3. (Assuming you have 9V at the battery)
Pin 3 should be

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Yes, Guitar Pickups are very Hi-Z devices.
But the input Z of an OpAmp with feedback should approach
10meg Ohms or more. Even without the feedback loop
a standard 741 has a 2meg input on it.

My gut is telling me the chip may have been damaged.
I have seen a lot of 741s go south quietly.  Some had
some strange failures where they seemed to work
but only partly. 

-Mike

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First let me say that the Texas Instruments datasheet is wrong....
Op-Amps are not for everyone.  My brother in-law for example. 

Secondly let me say...
    Wellll.ExcuuuuuuuUUUuuuuse me. 

Forgot my Inverting vs. Non-inverting rules for a sec there.
(shesh so picky.)

Heres my best (and feeble) attempt at a NON-Inverting, HI-Z input
Version of the same circuit..

Go ahead , rip it up.  I know you are dying to..

I'll take my hurt little feelings over here and calculate some Hfe gains
until I feel better.

-Mike

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I was searching in the iternet and I want to make a fuzz effect for my electric guitar. Because I found one and not work. Can anyone help me?


Jesus,
There is nothing wrong with the design of your fuzz circuit. In fact, it is an older classic fuzz circuit from the 60s or 70s as I recall. I recommend that you check for mis-connection. Also, I would recommend that you replace the 1N4001 diodes with 1N914. You could even replace these with LEDs and the circuit would work. Also, I suggest that where you have a 1Meg ohm resistor, make this a 1K ohm resistor with a 1M pot in series. This will give you a level of fuzz adjustment. Note that it will also act as a volume control.

MP
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It is the same circuit as the opamp circuit by Jesus a couple of days ago.
Its 1k input imedance is too low for a guitar's pickup.


R3 has no direct effect on the impedance of the guitar pickup. The value of R3 is selected to provide two things:
1. amplification with respect to the feedback resistor and
2. Filtering as per calculation with C1.

You guys missed the input cap. Jesus and Aaron win the prize with the effect that will not load down the guitar pickup as the volume is changed.

MP
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R3 has no direct effect on the impedance of the guitar pickup. The value of R3 is selected to provide two things:
1. amplification with respect to the feedback resistor and
2. Filtering as per calculation with C1.

You guys missed the input cap. Jesus and Aaron win the prize with the effect that will not load down the guitar pickup as the volume is changed.

MP


Sorry MP but you are wrong.
R3 is the input resistance of the inverting opamp amplifier which is 1k ohms. The 0.47uF input coupling capacitor has a reactance of 1k ohms at 340 Hz, so the load to a guitar pickup is only 2k ohms at 340Hz and less at higher frequencies.

Many experts say that a guitar pickup must be loaded with a very high impedance:

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Sorry MP but you are wrong.
R3 is the input resistance of the inverting opamp amplifier which is 1k ohms. The 0.47uF input coupling capacitor has a reactance of 1k ohms at 340 Hz, so the load to a guitar pickup is only 2k ohms at 340Hz and less at higher frequencies.

Many experts say that a guitar pickup must be loaded with a very high impedance:


Well, I just got back from a business trip and found your post.
No. I am not wrong. Some of the guitar effects which use a 1K input resistor to the op-amp are:

Ibanez Graphic EQ
MXR Flanger
Ross Stereo Delay
Ibanez TS9 Tube Screamer
Ibanez TS-808 Tube Screamer
MXR Hot Tubes Distortion
MANY MANY more........

Also, note that you are mis-quoting the "experts" regarding the guitar pick up. All guitar pick ups have loading provided on the guitar circuitry under the plate. You do not need to add it. Guitar pickups do not connect directly to the jack.

I have actually been one of these guitar effects "experts" since the mid 70's.
Also note that the C1 and R1 combination makes for a low cut frequency calculated as C=1/ (6.28)*(Low Cut off freq in HZ)*(R1).


MP
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National Semiconductor discontinued making their LF351 opamp.


Sry about that. Here's a circuit that can be built around a TL071, TL082, or LF351 if u have one. They all have the same pin connections. The gain's about 100.

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No. I am not wrong. Some of the guitar effects which use a 1K input resistor to the op-amp are:

Ibanez Graphic EQ
MXR Flanger
Ross Stereo Delay
Ibanez TS9 Tube Screamer
Ibanez TS-808 Tube Screamer
MXR Hot Tubes Distortion
MANY MANY more........

I have actually been one of these guitar effects "experts" since the mid 70's.
MP

MP, you have shown that you don't know about the input impedance of opamp circuits.
An inverting opamp circuit has a very low input impedance provided by its input resistor. A non-inverting opamp circuit has a very high input impedance provided by its DC-reference-voltage resistor to ground.

The "MXR Flanger" circuit has a 1k resistor at its input in series with a 470k resistor. Its opamp is non-inverting and the circuit's input impedance is 471k.
The "Ibanez Tube Screamer" circuit uses a 1k resistor at its input in series with a very high input impedance emitter follower. Its input impedance is also about 470k.

Many Fender guitar preamp circuits use a vacuum tube with a 1M resistor as its input impedance.
Many other guitar preamp circuits use a 10M resistor as their input impedance.

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