Zendrive

Capacitors        
C1    470n     470NF 100V 5% POLYESTER FILM BOX TYPE CAPACITOR
C2    100p     100PF 50V CERAMIC DISC CAPACITOR
C3    100n     100NF 100V 5% POLYESTER FILM BOX TYPE CAPACITOR
C4    3.3n      3.3NF 100V 5% POLYESTER FILM BOX TYPE CAPACITOR
C5    470n     470NF 100V 5% POLYESTER FILM BOX TYPE CAPACITOR
C6    100u     100UF 35V ELECTROLYTIC CAPACITOR 6X11MM
C7    47u       47UF 25V ELECTROLYTIC CAPACITOR 5X11MM

Diodes        
D1    BAT41        BAT41 diode
D2    BAT41        BAT41 DIODE
D3    BAT41        BAT41 DIODE
D4    1N4001      1N4001 DIODE 1A 50V

Transistors
Q1    BS170       BS170 BS170RLRAG MOSFET N-CHANNEL
Q2    BS170       BS170 BS170RLRAG MOSFET N-CHANNEL

IC
OP1   NE5532     NE5532 DUAL LOW-NOISE OPAMP
OP1   Socket       8 PIN DIP IC SOCKET ADAPTOR

Resistors        
R1     2M        2M OHM 1/4W 1% METAL FILM RESISTOR
R2     470k     470K OHM 1/4W 1% METAL FILM RESISTOR
R3     1k         1K OHM 1/4W 1% METAL FILM RESISTOR
R4     1k         1K OHM 1/4W 1% METAL FILM RESISTOR
R5     10k       10K OHM 1/4W 1% METAL FILM RESISTOR
R6     1k         1K OHM 1/4W 1% METAL FILM RESISTOR
R7     10k       10K OHM 1/4W 1% METAL FILM RESISTOR
R8     10k       10K OHM 1/4W 1% METAL FILM RESISTOR

Potentiometers        
VOICE      10k-B        10K OHM LINEAR TAPER POTENTIOMETER
TONE       50k-B        50K OHM LINEAR TAPER POTENTIOMETER
GAIN        500k-B      500K OHM LINEAR TAPER POTENTIOMETER
VOL         100k-A       100K OHM LOG TAPER POTENTIOMETER

PCB
ZENDRIVE   ZEN DRIVE DIY PCB

SCHEMATIC

TRANSISTORS

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

GENERAL DESCRIPTION OF COMPONENTS

Resistors

Use a multimeter or the color bands to obtain the resistance value. 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

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.

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.