Motivation
This is a useful and often needed utility module. The input voltages are precisely added to the outputs.The inputs 1, 3 and 5 are normalized. It can be used in different ways: As three independent adders, as buffered multiple, adding a modulation source simultaneously to all three outputs, adding two, three or four voltages precisely and a few more, depending on your patch. The accuracy depends on the used operational amplifier. For pitch CV I recommend precision OpAmps like the LT1014.
Specs and features
- 3 independent precision adders
- Input 1, 3 and five normalized
- Buffered multiple
- Additional common modulation inputs
- Runs on +/-12V and +/-15V
- Power consumption below 10mA each rail
Implementation
Schematic
Precision Adder schematic: Main board
Precision Adder schematic: Control board 02
Description:
All inputs are buffered with high impedance inputs. They are followed by precision adders where the two inputs and the two additional modulation inputs are added together. The last stage buffers the output and corrects the phase. Inputs 1, 3 and 5 are normalized.
Calibration
- None
Building hints
- The accuracy depends on the used operational amplifier and the matching of the resistors. For pitch CV I recommend precision OpAmps like the LT1014. Match all 10k resistors to 0,1% or better.
Special parts
- None
Download
Precision Adder main PCB documentation downloadPrecision Adder main PCB Gerber files download
Precision Adder control PCB documentation download
Precision Adder control PCB Gerber files download
Precision Adder: Front view
Precision Adder: Populated main PCB
