RangemasterThe Rangemaster is the most classic treble booster from the 60s, used by Eric Clapton or Brian May. This pedal produces a brighter tone and adds color to the signal.
Designators and components Step 2 of 5
C1 4.7n 4.7NF 0.0047UF 100V 5% POLYESTER FILM BOX TYPE CAPACITOR
C2 47u 47UF 25V 105C RADIAL ELECTROLYTIC CAPACITOR 5X11MM NICHICON
C3 10n 10NF 0.01UF 100V 5% POLYESTER FILM BOX TYPE CAPACITOR
C4 47u 47UF 25V 105C RADIAL ELECTROLYTIC CAPACITOR 5X11MM NICHICON
Q1 PNP 2N3906 / NPN 2N3904, BC108 or BC109
Socket 40 PIN DIP SIP IC SOCKETS ADAPTOR SOLDER TYPE
R1 470k 470K OHM 1/4W 1% METAL FILM RESISTOR
R2 3.9k 3.9K OHM 1/4W 1% METAL FILM RESISTOR
R3 1M 1M OHM 1/4W 1% METAL FILM RESISTOR
Bias 50k 50K OHM TRIMMER POTENTIOMETER CERMET 1 TURN 3362P
Boost 10k-B 10K OHM LOGARITHMIC TAPER POTENTIOMETER
The PCB is designed to build the positive ground (PNP transistor). To build to the negative ground version (NPN transistor): change to NPN transistor, flip the polarity of the electrolytic capacitors (C2 and C4) and connect the +9V where it is marked -9V.
Capacitors for PNP version Capacitors for NPN version
The original Rangemaster uses a germanium PNP transistor with gain between 75 and 100 (OC44). For the PNP silicon version, you can use 2N3906. For NPN silicon version you can use 2N3904, BC108 or BC109.
Use the following figures, for the correct position of the transistors.
In the following table find some transistors you can use.
It is recommended to use sockets for the transistors. You can use 3 pin headers (40 PIN DIP SIP IC SOCKETS ADAPTOR SOLDER TYPE) or a transistor socket.
BIASING THE CIRCUIT
Use the trimpot to bias the circuit. Use a voltmeter to measure the voltage on the "Bias" pad and adjust to -7 V (+7 V if using NPN). Note that if you are using germanium transistors the biasing will be influenced by temperature.
To add more bass to the output signal, use any value between 4.7n and 100n in the capacitor C1. The higher the capacitance, the more low frequency is amplified. You can use a switch (toggle or rotary) to select between several values.
POWER SUPPLY CHAIN WITH POSITIVE GROUND PEDAL
A positive ground pedal cannot be directly connected to the power supply in chain with your other negative ground pedals. You can use the Charge Pump PCB to build a voltage inverter and power your positive ground pedal in chain with the rest of your pedals.