Description
We learn all about lock-in amplifiers while trying to repair a classic Stanford research Systems SR510. It says "flaky PLL" on it. Analog electronics adventures ensue.
Principles of Lock-In Detection by Zurich Instruments: https://www.youtube.com/watch?v=ZIjBRA2S0NQ
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"Elevator Music" Credit: Crinoline Dreams by Kevin MacLeod
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00:00 The glorious SR510
01:28 Lock-in amplifier principle
05:54 We have problems
06:59 Purpose of the PLL
08:20 We have PLL jitters
10:58 PLL principle
13:03 PLL input circuits
14:41 Input circuits debug
15:50 PLL main circuits
19:16 PLL output check
20:36 PLL phase detector check
23:00 PLL control voltage check
25:05 Breaking the PLL loop
29:06 Maybe boundary switching is bad?
29:51 Comparing with a good instrument
30:47 VCO capacitance experiment
32:07 Back to head scratching
33:14 We have revelation
34:50 PLL check: all is good
36:01Multiplier check: all is good
38:13 Locking in a 50 nV signal
41:40 Spectrophotometer demo