the DIY function generator using an Arduino
This is my design files and progress on my take on building a Function generator . The main chip responsible for generating the waveforms is the Analog devices AD9833. This is a very capable chip , it can gererate sine, triangle and square waves from 0.1 Hz to 12.5 MHz although the target will be using it with a maximum of 10mhz.
The target future set will be the following
- Bandwidth 10MHz
- 12vPP amplitude
- 6v offset
- Full digital control of every parameter .
Building a Function generator proven to be quite a complex task , from the symmetrical psu needed to power the operational amplifiers to the voltage references used to “normalize” the AD9833`s output that has a +300mV offset plus the lack of free time to debug hardware on the breadboard lead to the project be left aside . the following items are what is being found working at some point .
-
Power supplies *Dual power supply without center tap transformer (not recommended ,it does not have full bridge rectifier)
*Dual power supply with center tap transformer (recommended but more expencive)
-
Front end :
-
offset control
-
UI design
- Offset correction The AD9833 as mentioned previously outputs a “bad” signal containing a +300mV DC offset , while outputting sine and triangle waves and this is quite undesirable. So to rectify this I used a voltage Summing circuit , to add -300mv so the signal will be back to “normal” AC , or how I want it to be output . the opamp there (NE5532) U10.1 , being part of the circuit , serves as a voltage follower . […..]
- Output amplification i wanted my generator to have a 10Vpp output , and the digital potentiometer (MCP41HV51) U8 cannot handle it , so up to this op-amp i have a "low" voltage then i boost it to the desired level.
Project is: in progress, but no longer continue due to constrained free time cause of University , I might get back to it at some point