Building a relay module to switch AC power.

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Building a relay module to switch AC power.

Postby domdom » Tue Jul 05, 2011 12:11 pm

Hello there,
I would like to design a small relay module to switch on/off AC power with micrcontroller Digital I/O.
I have completed the design on microcontroller side, the problem is I don't know what kind of relay can be used to switch AC power(Normally I use to switch DC power only).

Is cytron selling relay that can switch AC power?

Thanks.
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Re: Building a relay module to switch AC power.

Postby shahrul » Tue Jul 05, 2011 12:56 pm

DC Relay also can switch AC current.
or can do DC Relay + AC Relay. Microcontroller activate DC Relay, then DC Relay activate AC Relay.
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Re: Building a relay module to switch AC power.

Postby robosang » Tue Jul 05, 2011 9:21 pm

All relay can switch AC/DC because basically is just metal connection, and most of them are rated at 250V or 125V.

Just activate the relay using DC, if you want an AC activated relay you will still need to control that AC, right? Why want to trouble yourself? The main thing about AC is the voltage and current you want to switch, normally for protection/safety purpose the circuit will have a fast blow fuse in series, looking the load and fine a closest but higher ampere fast blow fuse, that should be good enough.
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Re: Building a relay module to switch AC power.

Postby domdom » Tue Jul 05, 2011 11:15 pm

robosang WROTE:All relay can switch AC/DC because basically is just metal connection, and most of them are rated at 250V or 125V.

Just activate the relay using DC, if you want an AC activated relay you will still need to control that AC, right? Why want to trouble yourself? The main thing about AC is the voltage and current you want to switch, normally for protection/safety purpose the circuit will have a fast blow fuse in series, looking the load and fine a closest but higher ampere fast blow fuse, that should be good enough.


hm..because I need to switch off/on on a few AC devices on certain time. That's why I am thinking to use microcontroller to do the switching.
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Re: Building a relay module to switch AC power.

Postby sich » Tue Jul 05, 2011 11:44 pm

Besides voltage rating, you also need to make sure the current rating for the relay is high enough for your application. I'm using the normal relay like this to turn on two energy saver light bulb for my car porch.

Otherwise you can get this and this.
~> How to ask QUESTIONS the SMART way in FORUM? <~
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