I was looking at the specifications for the OpenSprinkler pi (reproduced here):
Specifications:
Input Voltage:22V AC to 30V AC.
DC Output Current:500mA @ 5V (to power RPi).
Number of Zones:8 on the OSPi, expandable by linking zone expansion boards.
AC Output Current:800mA continues @ 24V AC per zone / station, 8A impulse / inrush.
Over-voltage Protection:48V bi-directional TVS on each zone, AC input, and rain sensor terminal.
Over-current Protection:2A on AC input; 1A on 5V DC.
Size:135mm x 100mm x 32mm (5.3” x 4” x 1.26”)
Weight:150g (5.3oz) w/o RPi
I don’t see where the over-current protection comes from.
For the AC, I see one connector directly connected to GND, the other connected directly to the COM connector. The triac connects the pin of the solenoid directly to GND. I see no circuitry to limit the current.
For the 5V, I see a switching power supply configured for 2A with a 12V input This part has a current limit, but it is significantly higher than 3A. I don’t see any other current limiters on the 5V.
I do see the TVS diodes for voltage limiting, I just don’t see any circuitry for current limiting.
Can you tell me how you came up with the over current protection numbers?