VFO-005

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VFO-005 P17270-720px.jpg

Variable Frequency Oscillator (VFO)

AD9833 based design.

  • Arduino Pro Mini
    • 3.3V/8MHz
  • AD9833 Function Generator
  • DC to 12.5 MHz
  • Rotary Encoder/Breakout Board
  • 128x32 OLED
  • Breadboard Power Supply
    • 3.3V operation
  • Mini-360 Voltage regulator (in case)
    • 5-24 VDC input

AD9833 Function Generator

AD9833s-P17243-720px.jpg

  • Digitally programmable frequency and phase
    • 12.65 mW power consumption at 3 V
    • 0 MHz to 12.5 MHz output frequency range
    • 28-bit resolution: 0.1 Hz at 25 MHz reference clock
    • Sinusoidal, triangular, and square wave outputs
    • 2.3 V to 5.5 V power supply
    • No external components required
    • 3-wire SPI interface
    • Extended temperature range: −40°C to +105°C
    • Power-down option
    • Update Rate: 25(max)
    • VOUT Maximum: 0.65V
    • VOUT Minimum: 38mV
    • VOUT Temperature Coefficient: 200°
    • Input High Voltage: 1.7-2.8V
    • Input Low Voltage: 0.5-0.7V
    • Input Current: 10µA
    • Input Capacitance: 3pF
    • Operating temperature range is −40°C to +105°C; typical specifications are at 25°C

Arduino Pro Mini

  • 3.3V
  • 8 MHz

2014-05-14T23 52 48.894Z-2-720px.jpg

ArdProMini-Pins.PNG

Rotary Encoder/Breakout Board

RotaryEncoderCAD.PNG

Si5351 004 720px.jpg

128x32 OLED

  • Ebay
  • 5V/3.3V operation

VRO-004 P17146-720PX.jpg

Breadboard Power Supply

  • On breadboard build

BrBdPS-IMG 4809-720px.jpg

Power Distribution Board - Revision X1

PowerDistrib-Front.png

  • Two headers with 6x2 pins each
  • Six pins bussed together
  • Ground connection header
  • Rounded Corners
  • 4 mounting holes for 4-40 screws

Breadboard

P17251-720px.jpg

Schematic

VFO-005 Schematic.PNG

Build

  • DC jack, power distribution card and Mini-360 voltage regulator

VFO-005 P17258-720px.jpg

  • All of the parts get jammed into the box
  • Some are hot glued

VFO-005 P17261-720px.jpg

  • Cutout for OLED
  • Running with frequency counter

VFO-005 P17267-720px.jpg

  • Display looks great in person not as good on picture

VFO-005 P17270-720px.jpg

Measurements

  • 10 KHz to 30 MHz
  • 20 dB attenuator (gain set in tinySA to -20dB)
  • VFO-005 set to 10 MHz
  • Sinewave
  • VFO set at 10 MHz

TinySA 10MHz-Sinewave From DC to 30MHz .png

  • Triangle wave

TinySA 10MHz-Trianglewave From DC to 30MHz .png

  • Square wave

TinySA 10MHz-Squarewave From DC to 30MHz .png

  • Half square wave

TinySA 10MHz-HalfSquarewave From DC to 30MHz .png

  • 7 MHz sinewave

TinySA 7MHz-Sinewave.png