Notes on choosing resistor values

The resistor values that we have suggested have been chosen to deal with 0-10V range CV input (although safe for -12V - +12V) and scale it to the 0-4.096V input range of the analog inputs on Bela, with the potentiometers acting as attenuators of the signals.

The values of resistor we have provided generally do a fine job at giving you the vast majority of the range of the analog inputs. However, due to varying tolerances in components there may be a 5% +/- of range that is not utilised (either through clipping or through the signal not reaching the full range of the input).

If you want to be extra sure to use the full range of the analog input we recommend measuring the resistance of each component, in particular each potentiometer and relative resistor in the voltage divider namely:

• R12 and POT1
• R3 and POT2
• R1 and POT3
• R5 and POT4
• R17 and POT5
• R19 and POT6
• R21 and POT7
• R23 and POT8 You should try to match the actual resistance of the pot and resistor as best as possible according to the voltage divider equation aiming for 4.09V as an output when 10V is passed through the divider and treating the fixed resistor as R1 and the potentiometer as R2.

 + ---------- Vin, from other Eurorack gear (0-10V)
 |
 Z  R1 (fixed resistor) 
 Z
 |
 | R2 (potentiometer)
 Z/ _________ Vanalog, connected to Bela (0-4.09V)
/Z
 |
 +_____Gnd

Customisation of input range

If you would like to deal with another range of voltages by default, if for example you have no intention of interfacing the board with Eurorack voltages and would prefer to use it as a standalone version of the Bela for prototyping that all runs on 5V, then you can experiment with the values of these resistors.