Near Intersection of I-35 & I-90 Southern Mn. | notillgleaner - 2/15/2021 21:43
JD8520 - 2/15/2021 16:50 I have 18 sections on my 90 ft boom. I wired in a manual switch at each valve out on the boom. It works great! I'm starting to like this idea. Is there any risk in back feeding 12v when you add those switches out there?
Yes there could be. This would depend on the system. With a Raven 440/450 controller without section control, this could work fine and actually be desirable. The Raven would be set with the Master ON, all section switches OFF, the desired target rate entered, the Rate 1/Rate 2/MAN switch set to automatic and the expected ground speed set in as a self-test speed. At this point, no valves would be open. Then as you walked around and flipped a switch to turn ON a section, 12V would be sent to the valve to open it and also back to the controller where it would try to control the spray rate as if you were actually travelling the self-test speed at the selected target rate.
With other controllers, back feeding could cause a problem. To be on the safe side a SPDT switch (3 terminals) is advised
SPST stands for Single Pole Single Throw. These switches have only two terminals. This is the most basic switch where flipping the switch one way completes the circuit between the two terminals. Flipping it the other way breaks the circuit. Splicing in one of these would allow the operator to turn the valve on while walking around it but might cause damage due to back feeding. A better plan would be to use a SPDT switch.
SPDT stand for Single Pole Double Throw. These switches have three terminals. The center terminal is called the Common. When the switch is flipped to the left, the common and right terminal are connected together. When the switch is flipped to the right, the common and left terminal are connected together. The center or common terminal is always connected to one or the other outer terminal but never both at the same time.
If the sprayer uses ball valves that use a constant hot, a constant ground and a trigger wire follow the drawing below. Determine which wire is ground, leave it alone as it will not be modified and will continue to go to the valve as original. Determine which of the two remaining wires is constant 12V and which one is the section valve trigger wire. Cut the one that is constant 12V and put a ring terminal on the cut portions. Attach these two ring terminals to one of the outer terminals of the SPDT switch. At this point 12V would still be reaching the valve to run the motor but also be connected to an outer terminal of the switch. Then cut the trigger wire and install ring terminals on those cut ends. Attach the end coming from the sprayer to the other outer terminal. The cut end leading to the valve is attached to the center terminal of the switch.
In my drawing the switch is set for normal operation and the sprayer would behave as original. If the switch were flipped down, the common would receive 12V and open that section for testing. Return the switch back up after checking that section to return to normal operation.
Edited by tedbear 2/16/2021 06:38
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 IMG_1041[1] (full).JPG (63KB - 103 downloads)
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Sprayer boom remote
