Dear All,
I've built a simple op amp summing amplifier using an LM358 (see attached). The circuit is used to control the electrostatic scanning plates for a charged particle beam. A saw-tooth function (1 kHz) is applied to one of the summing inputs and a DC offset is applied to the other. However, the output from the op amp has a "ripple" artifact (see attached photo's). Has anyone ever seen this before, or see anything blatantly wrong with the circuit? (I'm a physicist, not an electronic engineer, by training so please be kind!)

Cheers

 

Can you try the same circuit but with a true dual power supply?

 

Please show the X and Y scale units and zero level of the oscilloscope.

Did you forget to ground the two 10k resistors of the pseudo split supply in the circuit schematic as well as the actual circuit?

 

This is a crossover distortion not a ripple. Very common in LM358
http://www.electro-tech-online.com/threads/lm358-significant-data-sheet-errors.125929/
To fix this add a 1K resistor connected between LM358 output and -Vcc

 

You say you aren't an electronics engineer, so did you copy this circuit from somewhere? Can we see the original?

 

Jony193, thank you very much, that's fixed the problem. Thanks all for your help.