Lock-in Amplifier Prototype

While working in the Nano-electronics lab, I’ve had the opportunity to exercise my talent for building and innovation. When I first joined the team, I was asked to do a presentation on lock-in amplifiers. I’m a kinesthetic learner, and so I figured the best way to learn about this sophisticated instrument would be to build one. Within a week I successfully built a palm-size lock-in amplifier and performed an experiment where I showed that a specific frequency of a flickering LED could be filtered out and amplified by the lock-in. In a real experiment this would be analogous to filtering signal from noise by exciting a device with a reference frequency.

Left: two LEDs facing each other. The LED powered by an Arduino blinks at 10kHz. The blinking light is directed at the other LED which induces a current to be detected by the lock-in amp. A separate Arduino pin outputs a 5kHz signal directed to the … — Left: two LEDs facing each other. The LED powered by an Arduino blinks at 10kHz. The blinking light is directed at the other LED which induces a current to be detected by the lock-in amp. A separate Arduino pin outputs a 5kHz signal directed to the lock-in reference frequency input. The amplifiers locks on to this frequency and outputs only the signals that match this frequency.

Oscilloscope readings of the mini lock-in amplifier. Green is the input signal of the LED receiving the light. Magenta the signal of the flashing LED. Yellow the reference signal. Blue the amplified input signal (green) after locking on to the refer… — Oscilloscope readings of the mini lock-in amplifier. Green is the input signal of the LED receiving the light. Magenta the signal of the flashing LED. Yellow the reference signal. Blue the amplified input signal (green) after locking on to the reference frequency (yellow).