Taidacent AD630 2-Channel Balanced Modulator/Demodulator Amplifier Module for Weak Signal Detection

It is pretty much the AD630 reference design. Well packed. No documentation.

I had hope that this unit would actually function as a lock-in amp, using a photodiode and light chopper to create the signal and reference inputs. However I couldn't find a way to make it work properly for a signal with a DC component, i.e., it does not reject the DC as expected. Complicating matters, no instructions are included nor could I find any on the internet. I ended up abandoning this and bought a used "real" lock-in unit from an online source, for not much more $ than it cost to assemble this unit with the required +/- power supply.