Wah Pedal Guitar Effect Circuit

This is a design project for guitar effect called Wah Pedal Effect. Wah Pedal has been desing around since at least the early 60’s. The Vox is one of brand guitar effect which  is give beautiful sound and simple, only a couple of transistors and an inductor. The really pertinent question that had puzzled many people - including especially me - is how do you get a moving resonant frequency out of a fixed inductor and a fixed capacitor? How does that silly two-transistor Wah Pedal circuit get a moving band pass out of a circuit that changes neither the inductor value or the capacitor, but only what amounts to a volume pot? This  is the figure of the circuit;

Mic/Guitar Compressor Circuit Using Transistor Bias Control

This is a design circuit for compressor circuit that can be used for dynamic mic, condenser mic, or electric guitar pickup. This circuit doesn’t produce very good sound output, but it has very stable amplitude/volume. This compressor circuit design is unique since it uses base current control for manipulating the gain. This is the figure of the circuit;

The first and second transistor is an ordinary pre-amplifier, but the first transistor’s bias is controlled by the output signal to get a negative feedback. The third transistor is employed to control the dc voltage level at the junction of 1M resistor and 10uF cap that provide the first transistor bias current. The control mechanism is also unique, where  a full dc level at the capacitor is discharged at each half cycle of output when  it exceed the base forward bias. The gain control method by decreasing the base bias current of first transistor near its cut-off point produce a distortion, which might be unacceptable by some people especially for music/singing, but  can be acceptable for public address.  For electric guitar application, this compressor can be a good option since the distortion characteristic gives a unique effect, and the overshoot and undershoot of the amplitude stabilization gives something similar to “wow” effect from old recording.

Color Organ Electronic Circuit Using LM3909 IC

Using LM 3909 LED flasher IC, can be designed various electronic projects. As you can see in this circuit diagram, using the LM3909 LED flasher IC can be designed a very simple color organ. But this circuit is not complicated, it use just some common active audio filters for filtering audio signals and a part formed by a LM3909 IC. This is the figure of the circuit;

 

All of three active filters drives the audio spectrum into three bands drive rectifiers and then drive IC2,3 and 4, flashing the LEDs at 6 Hz. D4,D5 and D6 should be three different colors for best effect. In the table bellow you can see all electronic parts required by this color organ project.

Analog Tremolo (Guitar) Sound Effect Circuit

This is the circuit for the tremolo effect produce an amplitude modulated signal. Unlike vibrato effect that produce frequency modulated, this tremolo effect will produce the same effect as quickly turning up-ad-down your volume control repeatedly. This is the figure of the circuit;

Q1 is general small signal audio transistor, you can use almost any type of NPN small signal transistors. MFC3304P is a voltage controlled amplifier IC with negative control, it might be difficult to find these days, but I think you can replace with general OTA (operational trans-conductance amplifier), with the appropriate biasing circuit off course. Just bias the current control of an OTA through a resistor, and add the C4 modulator signal at the control pin of the OTA.

Passive Treble Control Circuit for Guitar Pedal

The R1/C1 network makes a low pass filter when the wiper is at the grounded end of the tone pot, and there is a treble cut. The C1 cap bypasses R2 when the wiper is adjusted so that it is at the top end of the pot and it creates a treble boost. This is the figure of the circuit;

The 100k output volume and the 100k tone pot are always in parallel as a constant load. It’s suggested to used a linear taper pot for the tone control and a log (audio) taper for the volume control. Suggested values for initial experimentation are R1=10k, R2=47k, and C1=0.022uF. Some signal loss, as with any passive network is the limitation of this combined tone control. However, many guitar pedal designs have strong enough output signal level, and this tone control is an excellent option for those circuits with enough drive.

A Frequency Doubler Effect for Electric Guitar

This circuit is a octave shifting that is used for electric guitar is done by rectifying the original signal, just like AC to DC conversion inside your AC-DC power supply adapter. This circuit is use single supply instead of symmetric power supply. This is the figure of the circuit.


The rectifying is done by four 1N4148 silicon diodes, configured as full-wave rectifier bridges. Because the bridge is inserted inside the negative feedback of the operational amplifier (op-amp) U1B, the nonlinear characteristic of the diodes around the turn-on point (the forward bias voltage) is compensated by the op-amp’s feedback mechanism. As the result, the output of the rectifier looks like coming from ideal diode with no bias voltage needed. The pre-amp gain can be adjusting by R3 potentiometer between clean and slightly overdriven, hear the effect, and set as you want. The R4 pot is provided to adjust the processed signal so the output level after the frequency doubling is equal to the level before entering this analog effect processor. Make R7, R8, and C3 layout as close as possible to the pin 10 of the LM324 IC (U1C) with shortest possible wiring to minimize capturing any noise. This voltage (at pin 10 U1) is the reference for internal “virtual ground” coming out from U1C output (pin 8). Make sure that the PCB tracks for this “virtual ground” (pin 8 U1) are wider than other signal tracks to give consistent reference for all op-amps. Make sure C4 and C5 have the shortest possible connection to the power pins (pin 4, pin 11) and the “virtual ground” line (pin 8).

Octaver Fuzz Guitar Effect Circuit

This is a design for guitar effect. This circuit is used for produces fuzz sound, so it is called fuzz effect. This circuit is built by low noise dual op amp IC and transistor. This is the figure of the circuit.


The GEU is good sounding octave fuzz, with an optional mode of just fuzz. The fuzz is a fully rectified signal and is quite chewy. For some the Fuzz alone might not be loud enough, this can be fixed by raising the value of the 820 ohm resistor and lowering the 39k one. Or one could just replace both with a normal volume pot for a more standard approach. The "struzz" is the fuzz with an octave higher signal mixed in. Good for signal notes and leads.

Ibanez Fat Cat Distortion Guitar Effect

This is a circuit for guitar effect that is good for blues, rock, pop, alternative, but not for metal. You can hear the fat tone even at maximum overdrive. Checkout’s the figure of the circuit.


How this circuit is work? The first transistor 2SC1815/BC546 is configured as voltage follower, giving high impedance for the input. The op-amp (5534 IC) serve an adjustable gain amplifier, to boost the signal until it reach the forward bias voltage (about 0.6 volt) of two 1N4148 diodes, where the signal is clipped. The tone controller is very simple, just adding a high frequency attenuation when the resistance is set to higher value. Finally, 2SK188/BF245 field effect transistor (FET) is used to buffer the tone control circuit to give low impedance output.

Controllable Tremolo Circuit

This is a design circuit for guitar effect. This circuit is a simple design and it is built by FET. This is the figure of the circuit.


This tremolo circuit is not a "plug and play" ready guitar effect, however it could be converted to one switching. with the relative ease. It just needs some buffering on the input and output and perhaps some bypass. This circuit is powered using 18 V DC.