I'm using a wein bridge oscillator as an audio tone generator in a radio modem (~2kHz). Ironically, when the transmitter is turned on, RF from the transmitter (~144MHz) causes the oscillations to die pretty quickly (a fraction of a second). If I hold the transmitter further away, it continues oscillating, but I'd prefer to reduce the EMI to have a more robust design.
I have a few questions I was hoping some people with EMI experience might be able to shed light on:
- Is the EMI likely cause by voltage fluctuation in the supply voltage, or the input lines to the op amp? Or maybe in the IC itself? I have a .01uF decoupling cap on the supply voltage (was out of 1uF caps), but maybe this cap needs to be larger?
- Would a low-pass filter on any of the op amp inputs be a good option, or would shielding be a better option?
- If I used shielding, would standard aluminum foil be adequate? What general guidelines are there regarding form and allowable holes in shielded enclosures?
Thanks in advance! Dave