diff --git a/bbn_m5atomS3_lite_alternator_freq_to_RPM/img/PC817_optocoupler_circuit.png b/bbn_m5atomS3_lite_alternator_freq_to_RPM/img/PC817_optocoupler_circuit.png
new file mode 100644
index 0000000..45f548b
Binary files /dev/null and b/bbn_m5atomS3_lite_alternator_freq_to_RPM/img/PC817_optocoupler_circuit.png differ