Nanoamp current source troubleshooting

[Kalvin]

If you have a light dimmer or similar nearby, the circuit wiring might act as an antenna and pickup the rectified 50 Hz mains from the dimmer (100 Hz ie. 10 ms).

[ZeroResistance]

If you have a light dimmer or similar nearby, the circuit wiring might act as an antenna and pickup the rectified 50 Hz mains from the dimmer (100 Hz ie. 10 ms).

Excellent suggestion, I have a light dimmer at a distance of 2 feet but its load is switched off, and there are other light dimmers about 4 to 5 feet away.
I guess the best way to circumvent this is by using proper pcb layout correct? I have built the circuit on a dotter board, not the ideal scenario for a low noise circuit. Having said that can I add any external components to qwell that noise?

[Kalvin]

Place the circuit inside a metallic cookie jar. Just make sure you have some insulation so that the circuit nor the battery won't short-circuit. Make holes for input and output signals/connectors and possibly a battery on-off switch. If you have some common-mode chokes at hand, you may also want to experiment with those whether they will help with reducing the noise. Anyway, I would first try the metallic container. And you will have some cookies, too