Signal Generator

[Dicky Mint]

Hi

I want to build a signal generator using a PICAXE.

I think I can generate the basic square wave up to ~4MHz

But how can I transform any frequency square-wave from DC to 4MHz into a sine-wave?

DM

 

[nick12ab]

I found this microcontroller-based electronic kit (datasheet) that can generate a sine wave by using a resistor ladder. It, however uses compiled code so can run faster than a PICAXE one. The DAC output on the PICAXE will make the task a little easier though so see how fast you can make that run.

See also: Click here for application notes and circuits for generating a sine wave.

 

[Dippy]

But how can I transform any frequency square-wave from DC to 4MHz into a sine-wave?

DM

Why don't you do what everyone else is doing ... Google.

Basically it's about filtering and you'll struggle if you want purity and a wide range.


If I were doing it I would look at controlling a Function generator chip.
Try Googling that.

 

[g6ejd]

I've done this in the past using a resistor ladder as nickab12 suggests, see attached. Surprisingly the purity of the output is not bad but the output impedance will be quite high, so would need to buffer it with say an op-amp LM355/741 etc. Mine was linked to a display and a double pole switch so that I could hold the switch on and get the PICAXE to increase the frequency and vice-sersa displaying the frequency on the display, worked well, but limited with respect to a custom function generator, but then the latter is no fun