DANGER - Hot chassis
This schematic is provided for historical information only.Notice in the EduKit schematics that the circuits incorporate a dangerous hot chassis connection. One side of the power line is connected directly to the chassis. DO NOT do this. Also, the 6 volt filaments are wired in series directly to the power line using the 330 ohm resistance connection in the resistance line cord.
If you decide to experiment with one of these circuits, I strongly recommend using a proper transformer to supply both filament power and electrically isolated higher voltage. Tube filaments can be wired in parallel for 6 volts. A pair of back-to-back 6 volt transformers could be used to supply the needed voltages. Also, some of the circuits connect the headphone to B+. This is not safe. I recommend using a proper audio transformer for headphone connection. If you are not familiar with these circuits or their dangers, do not attempt to build or experiment. Even somewhat safer tube circuits use high voltages.
Capacitors and resistors
Resistor R1 - is listed as "Any value between 1500 and 5000 ohms".
R2 is any value between 1 megohm and 3.3 megohm
R3 is any value between 22 K and 50 K ohms
R4 is any value between 100 K and 300 K ohms
C1 is .01 MFD
C2 is .001 MFD