We have described a simple and inexpensive digital phase-sensitive detector using a low-cost AVR microcontroller. To store a large number of data, we have added external memory (RAM) to the microcontroller. A message passing interface daemon-based software has been implemented to control the whole operation. Performance of the system has been tested using precise signals generated through a D/A converter controlled by an 8085 microprocessor. The phase resolution of the system has been reported to be better than 0.1 °. This phase-sensitive detector would be very useful for low-budget laboratories that deal with low-frequency AC signal applications.

1.
Richard
Wolfson
, “
The lock-in amplifier: A student experiment
,”
Am. J. Phys.
59
,
569
572
(
1991
).
2.
K. G.
Libbrecht
,
E. D.
Black
, and
C. M.
Hirata
, “
A basic lock-in amplifier experiment for the undergraduate laboratory
,”
Am. J. Phys.
71
,
1208
1213
(
2003
).
3.
K. D.
Schultz
, “
Phase-sensitive detection in the undergraduate lab using a low-cost microcontroller
,”
Am. J. Phys.
84
,
557
561
(
2016
).
5.
Science Prog,
“Adding external memory to Atmega128” (
2010
), <https://scienceprog.com/adding-external-memory-to-atmega128/>.
7.
“Tutorial material on MPI available on the Web,
” <https://www.mcs.anl.gov/research/projects/mpi/tutorial/>.
9.
See supplemental material at https://doi.org/10.1119/10.0000376 for program codes.

Supplementary Material

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