about: The pre amp used is a burr brown OPA2134 in two stages with melf metal film 1% resistors for low noise. Low noise is not realy needed for use with a walkman.. because they are quite noisy, but if you want to use it with other things like piezo elements or a guitar you can also use it to preamplify those.
A: The audio input is a Stereo 3.5mm jack input (all other jacks are mono jacks). It is Capacitor coupled. The tip of the connector goes to the pre amp, The sleeve goes to the 1VOctave tracking system.
If the volume goes above 1.4v PP it will be cut of by clipping diodes, the output can still reach the rails of the opamp on the output stage.
B: The audio output is Capacitor coupled. The output can be 10v PP, depending on the input.
C: CV input for controlling the audio output volume.
It takes 10v PP (adjust it up/down with E).
The circuit uses a vactrol, the curve it makes is anti log.. so it is somewhere between a gate and a pre amp.
D: Attenuation for the audio input signal.
E: Audio output volume. Moves CV input up or down.
317 regulator controller
F: CV input for adjusting L
G: Sets amount of offset from ground for L
H: 1v Octave input (the sleave of conector A is used for tracking information)
Range is 0v to 5v (the actualy octave range depends on the connected device, usualy the range is 2 to about 4 octaves).
M: Adjusts voltage of F.
L: Set voltage of output from I (317 output).
.: (small dot connected to M) 1v octave offset, 1 octave range, from C to C (that is the musical note C. Use a 2mm flat screw driver to adjust).
K: Activate 1v Octave tracking.
Adjustment menu for 1V Octave tracking:
- Hold the button while powering up (keep holding it for about 5 seconds.)
- The led in the button will blink when you let go of the button, if you push the button it will blink 1 time more, until you reach 7 blinks, then it will reset to 0 blinks, and you can go round again.
- If you hold the button for 2 seconds you will enter the next menu.
There are 3 settings you can change. after exiting the last settings menu your changes will be saved and used the next time you powerup the module.
Change the settings for how you feel the device you connected works best.
- adjusts the rise in frequency tracking (7 blinks is maximum).
- adjusts the fall in frequency tracking (7 blinks is maximum).
- adjusts the smoothnes in low voltage range (0 blinks is most stable (if lower then 2 blinks is used here, it can overshoot and get stuck, so its best to use at least 2 blinks here)).
about: This section is optically separated from the rest of the modular. This means the ground is not connected to the eurorack system and the power is also not connected to the eurorack system.
This is designed for driving small DC motors in walkmans, but you can also connect other things to it.. for instance a LED light or power a complete device with it.
I: 317 voltage regulator output. The output voltage is from 0v to above 0v. The actual output voltage depends on the power supply you connect to it. Maximum current draw is 500ma.
J: DC + in the center, maximum 12v DV input. It is advised to keep the input voltage between 6v and 9v, i use 7.5v If the input voltage is 12v the voltage regulator will get hotter then if you connect a lower voltage. the less hot it gets the longer it will fuction. Heat can also cause the output voltage to change (mainly because the vactrol can heat up)