Limit switch 1

[Max86]

I also asked this question in another forum but haven't received any replies back yet. This is driving me crazy trying to figure it out.

Hello I'm stumped on what I think should be very easy but having complete mental block on figuring it out. In the past I used a 12 volt linear actuator with adjustable limit switches to control length of movement. I wasn't satisfied with the speed of these actuators and went to stronger/faster actuators that could only use limit switches in dryer environments, I need them to work in wet environments so I'm using the new linear actuators without limit switches. I need to have somewhat very simple/adjustable limiting and at first thought about just using a DPDT polarity reversing switch (possibly a mom on-on mom on switch) that would contact a slider bracket mounted to the actuators but now don't think that would work like I would want, also I'm unable to even find such a switch without having it custom built. These actuators are somewhat continuously moving a load in/out and when the preset length were obtained, I need to be able to instantly reverse the direction if necessary. I currently use a DPDT mom on-off-mom on switch to control the actuators. I've searched for different switch configurations that might work but not seeing what might work and still have that mental block!

Any help would be extremely appreciated!

Max

 

[MikeHalloran]

Limit switches for wet environments exist, but they don't give them away.

Alternatively, you could just use super sturdy mechanical stops and current sensors, or use linkages to connect switches in a dry environment to mechanisms in a wet environment, or use a position transducer and do the switching electronically, or ... well, there's still half a universe of solutions that your current specification and problem statement has not ruled out.



Mike Halloran
Pembroke Pines, FL, USA

 

[ScottyUK]

I'm immediately tempted to suggest magnetic switches to deal with the environment and external relays or contactors to handle the power switching, but that's not a one-size-fits-all solution.

Any chance of a sketch or drawing of the equipment in question showing what you are trying to control?

 

[Skogsgurra]

Try this:

http://electronicdesign.com/compone...ed-limit-switches-flap-motor-control#comments

There is the usual non-informed "can't help showing my superior intelligence" comment about lamps burning out. To that I can safely say that lamps that are run at lower than rated voltage (red to yellow instead of bright white) have lifetimes that win over both little DC motors, and most limit switches.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[waross]

An elegant solution Gunnar.

Bill
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"Why not the best?"
Jimmy Carter

 

[cswilson]

Gunnar: Are you aware that Bill Hewlett exploited the variable resistance of a light bulb to stabilize a feedback circuit for Hewlett-Packard's first real product, an audio oscillator? Walt Disney was the first customer, using them in the production of the movie Fantasia.

 

[Skogsgurra]

Yes, of course! And my 202C generator still uses an "acorn" incandescent lamp to stabilize amplitude. Not very fast, I must say. And somewhat temperature sensitive. But low distortion. That's for sure.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.