60 Hz Variations in Pins Plugged probe into temperature controller output pins: pins 1, 2, 3, 4 all show 1V p-p variations Plugged probe into pins at other end of cable connected to temperature controller output: pins 1, 2, 3, 4 all show 200 mV p-p Touched probe to wires connecting temperature controller cable and photodetector assembly: pins 1, 2, 3, 4 show 200 mV p-p variations if amp is not connected and 100 mV p-p variations if amp is connected

Other Characteristics Temp controller on at DC Amps, connected to photodetector, photodetector signal variations of 4 mV p-p Temp controller on, but turned all the way down, takes ~10s to increase to 20 mV p-p Temp controller switched off but connected to power and photodetector, 2 mV p-p Temp controller disconnected from power, still connected to photodetector, 40 mV p-p, sensitive to my motion around electronics Disconnect temp controller from photodetector from temp controller end of cable, 10 mV p-p, sensitive to motion Disconnect temp controller from photodetector from photodetector end, variations are too small to distinguish from other variations/noise

Keithley Model 428 Current Amplifier PS/TC-1 Controller Labsphere photodetector casing InGaAs Photodetector and Temp Controller assembly Cooler (+) Cooler (-) Thermistor PD current signal Ground Connected to Amp ground Connected to temp controller ground To Power Strip Shielded Cable BNC Cable Ground Schematic

Schematic for Analog Board Power Supply from Keithley Model 428 Current Amplifier Manual

Figure labeled “Typical Connections” from Keithley Model 428 Current Amplifier Manual Pictures of photodetector and temperature controller connections