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XR-2206 Board[edit]

The XR-2206 board is based on the XR-2206, which is a single IC function generator. The board adds the external parts to make a sine wave generator capable of being controlled from the High Voltage Digital Pot or the High Voltage Digital Pot 2 board. This allows a microcontroller to digitally set the frequency of the output.

XR-2206 IC[edit]

The XR-2206 can generate a low distortion sine wave well above and below the audio frequency range. The Exar XR-2206 is no longer manufactured, but it is widely available on ebay from China.

Rev X3 Board[edit]

This is the third revision of the board.

Rev X3 Schematic[edit]


Rev X3 Layout[edit]


Rev X3 Mounting Holes[edit]

The board has three 4-40 mounting holes for either mounting horizontally with standoffs or vertically with an L bracket.

Rev X3 improvements over X2 version[edit]

Replaced Waveform adjust fixed resistors with 25K variable resistor (RV1). Split GVS header (J1) into GV and GS headers for separate power (J1) versus outputs (J3). Added a 3rd mounting hole.


The connectors are two pin 2.54mm (0.1") pitch headers.

J1 - Power[edit]

  1. +12VDC
  2. GND

J2 - Pot/Frequency Adjust[edit]

  1. GND
  2. Adjust

J3 - Output[edit]

  1. VCO Out
  2. GND

Rev X2 Board[edit]


Rev X2 Schematic[edit]


Rev X2 Connectors[edit]

J1 is Power/signal control circuit connected as GVS (Ground, Voltage (+12V), and signal output).

  1. Ground
  2. Voltage (+12V)
  3. Sine wave output

J2 is the connection to an external pot.

$ Ground

  1. Resistance

Rev X2 Parts List[edit]

Rev X2 Mounting Holes[edit]

The board has a single 4-40 mounting hole for either mounting horizontally with standoffs or vertically with an L bracket.


DDS from an Arduino

Rev X1 Board[edit]


Rev X1 Schematic[edit]


Rev X1 Board Issues[edit]

  • VGS silkscreen s/b GVS
  • Resistors are 1/8W leaving this point alone since it's small and I bought 1/8W resistors already
  • Dropped ground plane from .020 to .012"
  • Need pin 3 connections.
  • R1 s/b 10K
  • Changed C1, was 1uF, s/b 0.1uF
  • Pin 3 is missing waveform adjustment resistors