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XR-2206 Board

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

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

This is the third revision of the board.

Rev X3 Schematic


Rev X3 Layout


Rev X3 Mounting Holes

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

  • 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

  1. +12VDC
  2. GND

J2 - Pot/Frequency Adjust

  1. GND
  2. Adjust

J3 - Output

  1. VCO Out
  2. GND

Rev X2 Board


Rev X2 Schematic


Rev X2 Connectors

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.

  1. Ground
  2. Resistance

Rev X2 Parts List

Rev X2 Mounting Holes

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


Rev X1 Board


Rev X1 Schematic


Rev X1 Board Issues

  • 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