Jesus@wp4mhl Posted August 11, 2006 Report Share Posted August 11, 2006 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? Quote Link to comment Share on other sites More sharing options...
Theatronics Posted August 11, 2006 Report Share Posted August 11, 2006 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 Quote Link to comment Share on other sites More sharing options...
Jesus@wp4mhl Posted August 11, 2006 Author Report Share Posted August 11, 2006 OK this is the circuit that I have used I don't remember from were I got this but this is. Quote Link to comment Share on other sites More sharing options...
Theatronics Posted August 11, 2006 Report Share Posted August 11, 2006 SORRY, SORRY. Quote Link to comment Share on other sites More sharing options...
Theatronics Posted August 11, 2006 Report Share Posted August 11, 2006 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 3Appears to be the ground for the amp.I am not sure what the purpose of the 100uF cap onThe low side of the divider is. It may have been intendedTo filter out noise and keep the ground steady. In truth,As the current is drawn from the battery the source voltage willDrop and the 4.5v will drop also. If the battery gets low, suddenCurrent drains could cause the Virtual ground to fall BELOWThe stored voltage of the 100uf Cap. As the input resistanceOf the 741 is nearly 20M, it is likely the entire circuit couldShift 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 X1000The 1N4001 diodes then short out that formula at anyVoltage above 1 volt. (Under 1 volt the diodes tend toAct like resistors – Look up ‘Knee Voltage’)That means that any input signal will be allowed to see normalAmplification unless the output exceeds 1V Pos or Neg.The remaining capacitors are just DC blocking. They let the AudioSignal 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 Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 11, 2006 Report Share Posted August 11, 2006 I think that guitar pickups need a high impedance load like 1M ohms. The clipping opamp circuit has an input impedance that is very low at 1k ohms. The heavy loading on the pickup reduces its level. Quote Link to comment Share on other sites More sharing options...
Theatronics Posted August 11, 2006 Report Share Posted August 11, 2006 Yes, Guitar Pickups are very Hi-Z devices. But the input Z of an OpAmp with feedback should approach10meg 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 hadsome strange failures where they seemed to workbut only partly. -Mike Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 11, 2006 Report Share Posted August 11, 2006 But the input Z of an OpAmp with feedback should approach 10meg Ohms or more.No it doesn't!The negative feedback in an inverting opamp circuit creates a "virtual ground" at its inverting input where the input and output signals cancel. Therefore the input impedance is the input resistor. Quote Link to comment Share on other sites More sharing options...
Theatronics Posted August 12, 2006 Report Share Posted August 12, 2006 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 inputVersion 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 gainsuntil I feel better.-Mike Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 12, 2006 Report Share Posted August 12, 2006 Go ahead , rip it up. Quote Link to comment Share on other sites More sharing options...
MP Posted August 13, 2006 Report Share Posted August 13, 2006 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 Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 13, 2006 Report Share Posted August 13, 2006 Would this work? : http://www.aaroncake.net/circuits/fuzz.htmIt 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. Quote Link to comment Share on other sites More sharing options...
MP Posted August 14, 2006 Report Share Posted August 14, 2006 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 and2. 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 Quote Link to comment Share on other sites More sharing options...
Jesus@wp4mhl Posted August 14, 2006 Author Report Share Posted August 14, 2006 the circuit in the web link posted is that I was posted (I supose) and if I place an pre amp using an LM386. This will work? Quote Link to comment Share on other sites More sharing options...
MP Posted August 14, 2006 Report Share Posted August 14, 2006 Don't use an LM386 as a pre-amp. It will be too much for your guitar amp.MP Quote Link to comment Share on other sites More sharing options...
Jesus@wp4mhl Posted August 14, 2006 Author Report Share Posted August 14, 2006 If I place this Pre-amp will work Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 15, 2006 Report Share Posted August 15, 2006 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 and2. 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.MPSorry 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: Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 15, 2006 Report Share Posted August 15, 2006 If I place this Pre-amp will workNot very well. The LM386 is a small power amplifier, not a preamp. Just make a preamp with a high input impedance from an opamp. Quote Link to comment Share on other sites More sharing options...
Jesus@wp4mhl Posted August 17, 2006 Author Report Share Posted August 17, 2006 Can you send me a circuit for this preamp with an OP-AMP? Quote Link to comment Share on other sites More sharing options...
Guest nanop Posted August 17, 2006 Report Share Posted August 17, 2006 Don't use an LM386 as a pre-amp. It will be too much for your guitar amp.MPTry using a LF351 IC. Nanop Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 18, 2006 Report Share Posted August 18, 2006 Can you send me a circuit for this preamp with an OP-AMP?National Semiconductor discontinued making their LF351 opamp. I have been using the Texas Instruments TL07x series of audio low noise opamps.This guitar preamp circuit has a gain of 101, fuzz diodes and an input impedance of 1M: Quote Link to comment Share on other sites More sharing options...
MP Posted August 18, 2006 Report Share Posted August 18, 2006 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 EQMXR FlangerRoss Stereo DelayIbanez TS9 Tube ScreamerIbanez TS-808 Tube ScreamerMXR Hot Tubes DistortionMANY 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 Quote Link to comment Share on other sites More sharing options...
Guest nanop Posted August 18, 2006 Report Share Posted August 18, 2006 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. Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 18, 2006 Report Share Posted August 18, 2006 No. I am not wrong. Some of the guitar effects which use a 1K input resistor to the op-amp are:Ibanez Graphic EQMXR FlangerRoss Stereo DelayIbanez TS9 Tube ScreamerIbanez TS-808 Tube ScreamerMXR Hot Tubes DistortionMANY MANY more........I have actually been one of these guitar effects "experts" since the mid 70's.MPMP, 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. Quote Link to comment Share on other sites More sharing options...
MP Posted August 19, 2006 Report Share Posted August 19, 2006 MP, you have shown that you don't know about the input impedance of opamp circuits.yeah....whatever.... ::)...guess it was just luck that got me my Engineering degree.... you technicians could teach us a lot.MP Quote Link to comment Share on other sites More sharing options...
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