Three half H-bridge and a common half H-bridge that can be used to discharge a (9V/12V/24V) capacitively stored charge into one of three selected latching Solenoid coil. A current limited (300mA pk) boost converter (MC34063A) is on board to build up the stored charge from a low voltage (5V) supply.
To drive latching type irrigation solenoids with an RPUno.
The boost converter draws 300mA max, which leaves 200mA for other devices from a 500mA USB supply.
Latching solenoids are driven with a current pulse that last a short duration. The pulse flows in a coil and establishes a magnetic field. Since the pulse is a short duration the wire size to the coil can be significantly reduced, but some testing may be needed. One of the valves I use has a coil that measures about 4.7 Ohm with a DMM. I am able to drive it with 10 meters of CAT5 pair (24AWG) which has 1.7 Ohm. The peak current flow is over 3.5A for a very short time, so the wire does not get hot. I recommend that the peak current is less than about 5A otherwise the p-channel MOSFET safe operating time is too short to be robust.
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United States Postal Service: Priority Mail
Priority Mail Small Flat Rate Box will hold two RPUno, or two shields (RPUftdi or RPUadpt) and an RPUno.
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I am working on what may be thought of as a garden SCADA system, it is based on RS-422 and RS-485 and other well-known standards and the parts used to implement them. I have broken compatibility with common implementations in favor of trying to retain usability of existing RS-232 software (e.g. avrdude, picocom, PySerial...) and have an interface that uses interactive textual commands.