Stanford Research Systems SR510 Analog Lock-In Amplifier

Precision AC Signal Recovery, Since 1985 - Still a Workhorse in Labs Today

Measure signals as small as nanovolts, buried in noise a thousand times larger. The SR510 uses a precision analog sine-wave multiplier for demodulation - clean, harmonic-free signal recovery without the spurious responses that plague square-wave designs.

About the SR510

Single-phase analog lock-in detection - sine-wave multiplier eliminates unwanted harmonic pickup
True differential or single-ended voltage input, plus a dedicated current input
Three switchable input filters: line notch, 2× line notch, and an auto-tracking bandpass — cutting noise before it ever reaches the amplifier
Up to 100 dB of effective dynamic reserve when notch filters are engaged
Full computer control via RS-232 (standard) or GPIB/IEEE-488 (optional)
Internal reference oscillator - no external signal generator required for stimulus/reference

Key Specifications

Parameter	Specification
Reference frequency range	0.5 Hz – 100 kHz
Voltage input impedance	100 MΩ, 25 pF (AC coupled)
Current input	1 kΩ virtual ground, 10⁶ V/A gain
Full-scale sensitivity	100 nV – 500 mV (voltage); 100 fA – 500 nA (current)
Input voltage noise	7 nV/√Hz at 1 kHz
Input current noise	0.13 pA/√Hz at 1 kHz
Dynamic reserve	20 dB (Low) / 40 dB (Norm) / 60 dB (High); +20 dB with bandpass filter; up to 100 dB with line notch filters
Common-mode rejection	100 dB, DC to 1 kHz (degrades 6 dB/octave above 1 kHz)
Time constants	1 ms – 100 s (pre-filter, 6 dB/oct); 0, 0.1, or 1 s (post-filter, 6 dB/oct)
Phase resolution	0.025° steps; phase noise 0.01° rms (1 kHz, 100 ms, 12 dB TC)
Signal filters	Line notch (−50 dB), 2× line notch (−50 dB), auto-tracking bandpass (Q=5)
Analog I/O	4 A/D inputs, 2 D/A outputs, 13-bit resolution, ±10.24 V
Interfaces	RS-232 (standard), GPIB/IEEE-488 (optional)
Output	±10 V BNC, <1 Ω output impedance
Power	100/120/220/240 VAC, 50/60 Hz, 35 W max
Dimensions / weight	17" × 17" × 3.5" (rack-mountable), 12 lbs

Ideal Applications

Hall probe and strain gauge measurement, micro-ohm measurements, C-V testing in semiconductor research, low-level light detection, electron spin and NMR studies, and any experiment requiring recovery of small AC signals from a noisy background.

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