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Is this possible??

rescueweasel

Aug 29, 2014
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Aug 29, 2014
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I have a small CNC router that uses mach3 and the program turns on and off two switched ac outlets to control the vacuum and the router during cutting.

I have a small cutting laser which I want to attach to the gantry and use to cut, but it runs off 12 volts. I want to have its power controlled the same way as the router by the machine.

I hooked up an ac to dc converter and it powers the laser fine but the problem is that there is a lag coming on and the power tapers off when shut down. I need instant on and off of the 12 volts.

Is there such thing as a relay that I can have 12v in and out but have a 120v ac trigger? Or is there something better I could use.? The laser draws about 2.5 amps at 12 volts.

Thanks for the help.
 

Arouse1973

Adam
Dec 18, 2013
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Does the laser have it's own regulator? It could be there is some capacitance inside which is holding the supply up momentarily. So using a relay might not work. If it's just powered from the D.C adaptor then a relay should work as this will isolate the laser from the capacitance inside the adaptor. Can you post a picture of the laser and it's connection wiring.
Adam
 

KrisBlueNZ

Sadly passed away in 2015
Nov 28, 2011
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Yes, you can get relays with 120V AC coils that can switch many amps at 12V DC. You would have to leave your laser power supply plugged in, so you can avoid the startup delay.

Also I don't know whether it's safe to just disconnect the laser from the 12V supply - the supply voltage may rise when there's no load connected, then when you reconnect the laser, it could be damaged by brief overvoltage while the power supply stabilises again.

In other words, the power supply may be designed to be permanently connected to the laser, and breaking that path may be a bad idea.

I have no experience with lasers. I'm just raising this as a possibility. You're responsible for checking the suitability of this solution. I don't want you blowing up your laser. But more importantly, I don't want you blowing up your laser then trying to send me the bill!

Also be aware that AC-coil relays do not switch ON and OFF immediately either, but they will be a big improvement.

Assuming there's no problem with doing that, any of these relays will probably be suitable: http://www.digikey.com/product-sear...nSort=1000011&stock=1&quantity=1&pageSize=250

... but download the data sheet (click the PDF icon in the second column) and check that it's rated to switch at least 5A at 12V DC. (Relays are rated to switch AC and DC, and switching DC is more demanding. So a relay that can easily switch 10A at 250V AC may only be rated to switch 5A at DC.)
 
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