My AD9850 DDS project is finally complete. Another piece of test equipment that I built myself. Merry Christmas to me.
This signal generator covers up to 30 MHz. It is run by a NodeMCU wireless micro-controller. You can adjust the frequency by using the tuning knob or over WiFi.
The tuning knob is an rotary encoder that sends left and right pulses to the computer chip. When you press the knob down, you can adjust the tuning step, from 1 Hz to 1 MHz. The ESP-12E computer chip reads these pulses and sends control signals to the AD9850 DDS (direct digital synthesizer.)
Alternatively, the ESP-12E also shows up on the home network. This enables remote control of the device. When under WiFi control the word “Remote” shows up on the display.
Other features include: saving parameters to EEPROM, signal sweep, synthesizer calibration. Also included is synthesizer offset. This is where you can use the signal generator as an oscillator for a receiver or transmitter.
AD9850 DDS – Do you want to build one?
If you would like to build one of these for yourself, contact me. I can send you the models for the case and circuit board. I can also send you the source code for the software if you want to avoid writing it yourself.
The signal generator puts out close to 1 volt pk-pk, dropping as the frequency rises. There is plenty of room in the box if you want to add a buffer amplifier for a bit more power.
The parts are cheap. Current E-Bay prices in US dollars are:
- AD9850 DDS synthesizer $9
- NodeMCU wireless micro controller $4
- KY-040 rotary encoder $1
- I2C LCD display $2
- Plastic filament for case and knob $6
Add in the wiring, terminals and printed circuit board and you might hit $25 overall.