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Need Help with Relays
« on: March 02, 2013, 06:11:51 PM »
I have searched and read for hours, but can't find a solution to my problem.  Hopefully someone can help. 

I am new to CNC and everything has been going good.  I recently decided to utilize 2 SSR's to control my spindle and flood coolant.  I only want to turn the spindle on and off, not control the speed. 

I wired the relays according to several diagrams I found.  Using a 12V battery, they function as they should.

I have a camtronics box with 2 relay outputs connected to pins 16 and 17.

I have configured everything and can toggle the spindle/coolant outputs and get 5 volts.

Now the problem.  Even though the relays are rated to trip as low as 3V, they are not tripping with 5V.  Connect them to a 12V battery and they trip like they should.

Is there a way to increase the output voltage of these pins?
 

Offline Chaoticone

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Re: Need Help with Relays
« Reply #1 on: March 02, 2013, 06:25:45 PM »
Your outputs are not supplying enough voltage, or current or are not wired correctly.

Brett
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Re: Need Help with Relays
« Reply #2 on: March 02, 2013, 06:30:24 PM »
I have verified I am getting 5 volts to the relay when I toggle in mach3.  There is a little LED on the relay that lights as well, but it's very dim with the 5 volts.   I was hoping I could increase this voltage to avoid replacing the relays. 
Re: Need Help with Relays
« Reply #3 on: March 02, 2013, 07:52:31 PM »
I just looked at the spec sheet again for this relay.  If I understand it, it takes 3V to keep the relay on, but needs 12V for the initial trigger.  Is this correct?  Guess I need to shop for relays again  :(

Input Data                              
Operating Voltage    3~32VDC
Min. ON / OFF Voltage    ON > 2.4V , OFF < 1.0V
Trigger Current    7.5mA / 12V
Control Method    Zero Cross Trigger
Re: Need Help with Relays
« Reply #4 on: March 03, 2013, 10:29:19 AM »
I think that's just saying that the required trigger current is 7.5ma at 12V.  At 5 V it should be less.  It sounds like you don't have enough current to trigger the relay.  find a 5V, 1A or 2A power supply and connect it to the trigger input and it will probably work.

We stopped using SSR's a while back.  They are problematic.  They don't always work.  They usually won't work with motors that have capacitive start or any sort of built in speed control or relays/solenoids with AC coils.  
Re: Need Help with Relays
« Reply #5 on: March 03, 2013, 10:36:00 AM »
I think that's just saying that the required trigger current is 7.5ma at 12V.  At 5 V it should be less.  It sounds like you don't have enough current to trigger the relay.  find a 5V, 1A or 2A power supply and connect it to the trigger input and it will probably work.

We stopped using SSR's a while back.  They are problematic.  They don't always work.  They usually won't work with motors that have capacitive start or any sort of built in speed control or relays/solenoids with AC coils. 

Would you recommend a different type of relay?
Re: Need Help with Relays
« Reply #6 on: March 03, 2013, 10:46:08 AM »
Just use a mechanical relay rated for the current you need.  CNC3PC sells some good ones that can be driven from TTL 5V outputs.