- 1 XR-2206 Board
- 2 Rev X3 Board
- 3 Rev X2 Board
- 4 Rev X1 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.
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
J2 - Pot/Frequency Adjust
J3 - Output
- VCO Out
Rev X2 Board
Rev X2 Schematic
Rev X2 Connectors
J1 is Power/signal control circuit connected as GVS (Ground, Voltage (+12V), and signal output).
- Voltage (+12V)
- Sine wave output
J2 is the connection to an external pot.
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