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Electra Distortion

Simple Vintage Circuit


BASIC PC BOARD

This is the Electra PC Board showing the connections for audio and power. It accepts a 9v dc input in the basic configuration.

In some of the following circuits on this page, not all parts may be used. If a part is not shown on the schematic or in the parts list for one of the circuits, then it is not required for that project and can be left empty on the pcb.

The parts listed in these instructions are specific to the project that is presented for best performance, and though other parts can be substituted, the capabilities of the may be changed or diminished.

This is the full schematic to the pc board shown above. The design has been expanded beyond the basic vintage circuit. Power supply protection and filtering have been added, for example.



Full Parts List

===========================
R1 - 2.2M
R2 - 470 ohms
R3 - 4.7k
P1 - 100k audio taper
P2 - 100k linear taper
C1,C2 - 0.1 uF
C3 - 0.001 uF
C4 - 100 uF electrolytic
D1,D2 - 1N34a germanium diodes
D3 - BAT48 Schottky diode or similar
Q1 - 2N3904 or similar transistor

All resistors are 1/8w and capacitors are in uF and rated for 25v minimum.

This is the wiring for the off-board potentiometers that are used in this version.


BASIC ELECTRA

The original Electra did not have any potentiometers for control of volume or distortion. The player used the guitar's volume knob to control the distortion.

In the basic version, the input and output connections are made directly to potentiometer pads to avoid the use of additional jumper wires.

Note that a jumper MUST be used in place of D3.

Vintage Parts List
===========================
R1 - 2.2M
R2 - 470 ohms
R3 - 4.7k
P1 - none
P2 - none
C1,C2 - 0.1 uF
C3 - none
C4 - none
D1,D2 - 1N34a germanium diodes
D3 - jumper wire
Q1 - 2N3904 or similar transistor

All resistors are 1/8w and capacitors are in uF and rated for 25v minimum.

Parts that are not in the parts list are not required for the basic circuit and their positions on the pcb are left empty.


Electra Boost

This is the same parts list as the basic Electra shown above but without the D1 and D2 clipping diodes. I suggest that you use the 100k audio taper volume pot so that there is control of how much the signal is boosted. The boost version has been sold by several boutique pedal builders.


The Bazz Fuss

The Hemmo Bazz Fuss is a simple fuzz circuit that has nasty synth-like tones. It can be built using this pcb with a few changes.

Parts List
===========================
R1 - 1N4148 diode
R2 - jumper
R3 - 10k
P1 - 100k audio taper
P2 - 100k linear taper
C1 - 4.7 or 10uF electrolytic
C2 - 0.1 uF
C3 - 0.001 uF (optional)
C4 - 100 uF electrolytic
D1,D2 - not used
D3 - BAT48 Schottky diode or similar
Q1 - MPSA13 or similar transistor

All resistors are 1/8w and capacitors are in uF and rated for 25v minimum.

A wire jumper must be placed in the R2 position. In this fuzz, C1 is an electrolytic capacitor and the plus side should be oriented as shown in the pcb image. A silicon diode is usd in place of R1 and I have drawn a band on the R1 placement in the pcb image to show how it should be oriented. The band is not on the actual pcb. The black band on the diode goes to the same side as the band on R1.

This fuzz sounds best when driven hard by the guitar, so the P2 control is not much use. If you do not want to use the P2 Drive control, then you should jumper pad 1 to pad 2 inside the box marked P2. If you cannot find a Schottky diode, then substitute a 100 ohm resistor for D3.

Parts that are not used in the parts list are not required for this circuit and their positions on the pcb are left empty.

Q1 needs to be a high gain darlington transistor in this circuit. If you cannot find a MPSA13, then try KSP13, MPSA29 or even a 2N5089 or BC550.


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