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Motor Control Circuit With Stop Limiter And Position Sensor Readout

born riding

Jan 31, 2017
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Joined
Jan 31, 2017
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I am fairly familiar with dc wiring. i am making an independent trim system for a jet ski conversion build. i need to wire it according to the requirements below. trying to find service documents for the system before i cut up to make it. i don not know if i should use two relays or just use switch no relays. 12v power source. I flushed like $500 with my previous attempt, so am requesting some help first this time.

3 wire switch, 3 pos: up, off, down
up and down limiters
position sensor
position sensor readout( will find one thats fits sensor readout range)

i will post more tonight once i have more info, but just wanted to get this out there in case anyone who is good at this stuff is browsing and has any suggestions. thank you for your time
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Generic_Motor_Switch.jpg (21.25 KiB) Viewed 3 times
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MOTOR_SPEED_CONTROL_12V_APP_2.jpg (39.52 KiB) Viewed 3 times
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images.png (2.81 KiB) Viewed 3 times
 

Mike Van In

Feb 1, 2017
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Feb 1, 2017
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I'm not sure what suggestions you're looking for - unless you're asking if relays are better than simple switching - then, Yes. Your relay circuit is fine - it will run the motor in whichever direction you flip the switch.

Your (normally closed contact) limit switches should go in the green and blue lines from the switch. Obviously, the "Up" limit must go in the line that controls the "Up" direction and vice versa. It's not possible to say which way the motor will turn, from your schematic. So simply swap the motor wires if it goes the wrong way when first wired up.

Since your position sensor will likely be completely independent of the motor control it doesn't make any difference here.

Another option, which would fit well under the previous $500 expense, would be to link the pivot of the jet ski's trim to a potentiometer (variable resistor) and drive your trim motor as if it was a servo. Then you would control it with another potentiometer and the trim would just tilt to whatever you dialed up on your control. This kind of simple control is called a bang-bang servo (full voltage either way or off, not modulated according to position error) and works very well for simple positioning control - the main advantage for your application is that you don't need an eye on the position indicator. Set the trim dial and the automatically activated relay will drop out when the position of the pivot potentiometer reaches the same (within a selectable tolerance) as your controlling one.
 
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born riding

Jan 31, 2017
3
Joined
Jan 31, 2017
Messages
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thanks mike, after reading your response it made me think about a few things. first i will be using a waterproof 3 wire DPDT momentary switch. I like the idea of the servo style full power i will be pushing 550HP so it will probably need full power. with the bang band servo can i have 5 pre set stopping points (2 up, 1 nuetral, 2 down)? i really would like to have full control with stop at ends and ability to release switch and have nozzle stay where i put. but i would be ok with either as long as it is reliable and waterproof:) i will post some pics of what i have on hand which may help. i do have a complete system here but it needs another ecu and everything is controlled and read the the ecu and data tables. so i was thinking bypass electronics and low tech it as individual components. thoughts?
 

Mike Van In

Feb 1, 2017
2
Joined
Feb 1, 2017
Messages
2
550HP ?!! Eeek! On a jet ski?! Are you kidding me?

What does the trim motor look like? Now I'm imagining it's some kind of hydraulic hybrid. Do you have any data, if it's actually an electric drive? Photos would help a lot. It sounds like your system must already have an encoder or resolver built-in for reporting back the trim position. Details on that would be important too.
 
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