Box of Metal

The Box of Metal is a high-gain distortion pedal great for metal and hard rock.

Steps

Designators and components Step 2 of 5

COMPONENT LIST

PCB
BOX OF METAL DIY PCB GUITAR EFFECT

Potentiometers
GAIN 5k-C 5K OHM C5K 5KC ANTI-LOG TAPER POTENTIOMETER
VOLUME 100k-A   100K OHM LOGARITHMIC TAPER POTENTIOMETER
BASS 1M-A   1M OHM LOGARITHMIC TAPER POTENTIOMETER
MID 20k-A 20K OHM LOGARITHMIC TAPER POTENTIOMETER
TREB 250k-A 250K OHM LOGARITHMIC TAPER POTENTIOMETER

PCB

Note: there is a missing track on DHC12 PCB version, solder R22 and R23 pads as indicated in the following image.

SCHEMATIC

BIASING

Adjust Q5 gain with the varaible resistor "BIAS".

TRANSISTORS

The 2N7000 is a common replacement for BS170, however the pinout is a 180 degrees turn. Mount the transistors on the PCB as follows.

GENERAL DESCRIPTION OF COMPONENTS

Resistors

The resistors should be ¼ Watt metal type. You can either use a multimeter or the color bands to obtain their values. Resistors do not have polarity, you can place them in any direction.

Electrolytic capacitors

Electrolytic capacitors have their value printed on them. The negative polarity pin is indicated by a white strip along the can. They also have a longer leg indicating the positive pin. The maximum voltage rating never can be exceeded, make sure you are using at least double voltage rating than your power supply. For example, if you are using a 9V power supply, use a electrolytic capacitor with at least 18V maximum voltage rating.

Polyester capacitors

The polyester capacitors have their value marked with three numbers. Read as picofarads (pF), the first two are the 1st and 2nd digits and the third is the multiplier code. These capacitors do not have polarity, you can place them in any direction.

Ceramic capacitors

The ceramic capacitors have their value marked with three numbers. Read as picofarads (pF), the first two are the 1st and 2nd digits and the third is the multiplier code. These capacitors do not have polarity, you can assemble them in any direction.

Tantalum capacitors

Tantalum capacitors have the value printed on them. The polarity is marked for the positive pin. Additionally, the longer leg is the positive and shorter the negative. Assemble the tantalum capacitor according to the positive polarity (+) marked on the PCB.

Diodes

Diodes have their model printed on them. The polarity (cathode) is indicated by the ring near the side. This ring is also marked on the PCB.

Led diodes

Led diodes have polarity, the cathode is indicated as a flat surface on the side of the diode and also it is the shorter led. On the PCB, the cathode is marked as a flat side and anode as a round side.

Transistors

Transistors are three terminals components and their model is printed on them. To indicate the correct orientation, one side of the transistor is flat and the other one is round.

Potentiometers

Potentiometers have their resistance value marked on them. They are marked with A, B or C for logarithmic, linear and reverse logarithmic, respectively.

Trimpots

Trimpots are similar to potentiometers. Their values are printed on them. Use a small screwdriver to adjust them.

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Box of Metal

Steps

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Designators and components Step 2 of 5