Design a DSP lock-in amplifier, Part 2: Design methodology - EDN
Lock-In Amplifier Comparison
Using the Lock-in Amplifier to build an AM radio receiver - Liquid Instruments
Lock-in Amplifier (Moku:Pro) - Liquid Instruments
Punch Beat climax005 Tractor Lock DC Amplifier with 4440 Double IC with Bluetooth Digital FM/AUX/ MP3/ SD-MMC/BT/USB 1000W DC Power Amplifier : Amazon.in: Electronics