The Werkstatt comes with a coarse tune potentiometer in the form of the VCO FREQ knob. However, it is sometimes necessary to have a finer control over the VCO tuning. This modification adds a fine tune potentiometer to your Werkstatt.
2x 150kΩ Resistors
1 x 10kΩ Potentiometer
For this mod we will be pulling from the power supply taps provided on the Werkstatt's PCB. We will be accessing the +9V and -9V power taps. It is VERY IMPORTANT that we keep our Werkstatt UNPLUGGED while we are patching to and from our power supplies to ensure we don't accidently cross voltages and let the "magic smoke" out. We will be using two 150kΩ resistors to bring our voltage down to a usable level for fine tuning. If we were to not use resistors the voltage would be too much for our VCO EXP IN and could cause some problems. Refer to figure 1 for the terminal definitions of a typical potentiometer.
Figure 1. A, W, B terminal definitions of a typical potentiometer.
Run one jumper from the -9V taps at T1/T2 into a 150KΩ resistor attached to terminal A on our 10kΩ potentiometer. Run another jumper from one of the +9V taps at T9/T12 into 150kΩ resistor attached to terminal B of our pot. The signal that will control our fine tune will come from the wiper terminal (W) of our potentiometer into our VCO LIN IN. Before we plug our Werkstatt back in ENSURE THAT +9V and -9V ARE NOT TOUCHING AND ARE AT OPPOSITE SIDES OF THE POT...if incorrect this will let the "magic smoke" out. Refer to figure 2 for detailed jumper connections. Figure 3 provides us with a schematic view of our Fine Tune modification.
Figure 2. Fine tune jumper configuration.
Figure 3. Fine Tune schematic.
This project also comes with 3D printer files to print your own housing. See figure 3 for a 3D rendering of the top and bottom panels for this housing.
Figure 3. Fine Tune 3D enclosure.
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