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### Author Topic: Relay DC/ AC  (Read 4135 times)

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#### pipster55

• Newbie
• Posts: 5
##### Relay DC/ AC
« on: August 02, 2015, 19:28:34 PM »
Hi

I am curious, can a relay that was designed for DC electricity handle 120v AC?

Specifically, I have a relay that shows 12v DC input with 40A  14v DC switching and I'd like to control 120v AC power to a capacitor desulfator  that I built. I want to operate the relay with 12v DC put switch 120v AC.

#### kam

• Hero Member
• Posts: 1849
##### Re: Relay DC/ AC
« Reply #1 on: August 02, 2015, 20:25:19 PM »
Normally all mechanical relays state a dc and an ac switching capability. The coil (for you this  is 12dc) is not subject to change. The output though can control both ac and dc. Google the relay datasheet to be sure.

In the case of  solid state relay things are more strict. It might be that an ssr can control only dc loads.

#### pipster55

• Newbie
• Posts: 5
##### Re: Relay DC/ AC
« Reply #2 on: August 03, 2015, 17:35:41 PM »
I couldn't seem to locate it by the number printed on it but by Googling  40A  14VDC   DC12V   I found one that seemed to match. It apparently can handle 20a  120v.

I would like to pose a question ( it may need to be posted in another catagory) concerning wiring motor run capacitors in parallel. I have 5  /50mfd non-polarized run capacitors in which I am wanting to be able to switch on/off ( 1 on 3 off, 2 on 2 off, etc) so as to increase/decrease amperage at output. I have a jumper connecting input to input, and from output to switch to output. Not really certain as to testing capacitor output but reading with multimeter, voltage and amperage remain the same at output whether 1 or all are switched on. From what I understand there are multiple ways to switch the output. Perhaps I don't have them configured correctly for what I want to achieve.

Also, the output of the capacitors goes to one input terminal of 2  / 25a full bridge rectifiers which I have configured in parallel. These I have made switchable as well but having one or both on doesn't register differently with amperage reading with a multimeter. The remaining terminal of the rectifier has the other 120v lead.

#### kam

• Hero Member
• Posts: 1849
##### Re: Relay DC/ AC
« Reply #3 on: August 03, 2015, 19:08:33 PM »
It would be better to post your question with a schematic to explain exactly what you want.

#### pipster55

• Newbie
• Posts: 5
##### Re: Relay DC/ AC
« Reply #4 on: August 05, 2015, 02:52:14 AM »
Here is a photo.

#### pipster55

• Newbie
• Posts: 5
##### Re: Relay DC/ AC
« Reply #5 on: August 05, 2015, 18:01:02 PM »
For some reason I am having difficulty uploading jpeg of schematic. Seems to stall out on "sending request to pcbheaven.com"

#### pipster55

• Newbie
• Posts: 5
##### Re: Relay DC/ AC
« Reply #6 on: August 07, 2015, 20:35:27 PM »
schematic, layout