Q:

Sine wave generator -

I have put together a sine wave generating circuit. The signal goes through a transformer. The output signal of the transformer is detected and used for a measurement. 
Yellow signal - From sine wave generator
Blue signal - output from transformer (not really relevant here)
I am worried about the oscillations occurring on the output of the sine wave generator. The oscillations are only present when the transformer is attached. 
Are the oscillations due to not enough output drive current or from the transformer load? I am trying to understand what is going on here when the transformer is attached. 
The peak to peak voltage is 3.38V and the impedance of the primary is 500 ohms, secondary is 240 ohms. I am using the LM324QT op amp (https://www.digikey.ca/product-detail/en/stmicroelectronics/LM324QT/497-12005-1-ND/2772310). 

The schematic is shown here : 
[![enter image description here][2]][2]

simulate this circuit – Schematic created using CircuitLab
Thank you!

A:

Judging by the frequency of the oscillations alone I expect it may just be parasitics of the system. Some parasitic capacitance is turning your transformer winding into an LC resonant circuit and it's ringing at a high frequency. I see this all the time and the best way to prevent it is to critically damp the system by adding resistance to the output. The value of the resistance may need to be determined by trial and error in order to get a favorable waveform.

