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| -rw-r--r-- | circuit.txt | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/circuit.txt b/circuit.txt index 408f8ee..216ae5a 100644 --- a/circuit.txt +++ b/circuit.txt @@ -10,12 +10,20 @@ | | +--------------------------+ | | | | | +--|(+)\ | | \ Voltage | | | | | >---+ / / Pull-up resistor - Divider | | | +--------|(-)/ | \ ~10K + Divider | | | +--------|(-)/ | \ ~100K | | | \ / - | | | Comparator (NS M8830) | \ + | | | Dual Comparator (LM 393) | \ | | +--------------------------+ | | | |__| |__| |__| |__| | -24V ac o-+-\/\/\/\/--+ | | | - | 1K | +---------+----o Digital +5V + | 1K | +---------+----o Vcc | | - +---------------+----------------------------------------o Digital ground + +---------------+----------------------------------------o Ground + +The 120Vac <-> 24Vac transformer could be replaced by a larger voltage +divider, but that would couple the USB ground line to one pole of the +AC line. + +Comparator is LM 393 or equivalent, used as a zero-crossing detector. + +Digital output is connected to pin B0 of the Teensy. |