I am trying to hook up a train horn on my truck and I want to open a valve with a switch. I have a solenoid actuated valve that is 12V 400mA. Can I connect it directly to a switch from the battery, or will I need a relay or something else so I don't burn it out?
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1\$\begingroup\$ Almost any switch you get will handle 400 mA, although it will be a good idea to put a flyback diode on the solenoid just to increase the switch life. \$\endgroup\$– WhatRoughBeastCommented Sep 26, 2015 at 22:54
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1\$\begingroup\$ Maybe I am thinking backwards about this, I was worried that a 12 car battery would burn out the solenoid but now that I think about it, the solenoid should only draw the amperage it requires. Sorry, I'm no electrician, I have more of a mechanical mind \$\endgroup\$– Colin GarantCommented Sep 26, 2015 at 23:05
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\$\begingroup\$ Is it really necessary to install a 150psi compressor or whatever and a train horn just to scare the crap out of people? \$\endgroup\$– Spehro 'speff' PefhanyCommented Sep 27, 2015 at 1:05
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\$\begingroup\$ Not intended to scare people, but to get their attention. There was a car stopped in the middle of an intersection, the person didn't move when they were supposed to because they were texting. They didn't hear me honking because the music was too loud. Next time they will hear me. Besides, if people only did what was necessary, we wouldn't be having this conversation \$\endgroup\$– Colin GarantCommented Sep 27, 2015 at 3:17
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\$\begingroup\$ I can see this escalating to placing a gun turrett on the top of the truck controlled from the cab for instances when they don't hear the train horn. Que sera. \$\endgroup\$– Andy akaCommented Sep 27, 2015 at 8:45
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1 Answer
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A relay will make the same physical contact that a switch will. Most automotive switches could handle 400mA easily. Relays become important when the amperage being handled is greater, as when headlights are being used.
You could use a relay in a standard configuration with a switch if you want.
