Relay Specs

[daniel herring]

Hi

Picked up a couple of 8 channel relay boards to use with my Uno. I want to put them in parrell with my light switches so I can control the lights from the Uno. From what I can see the spec looks ok but the size of them makes me nervous. Can anyone comment on if these should be man enough for the job?

Hmm wanted to post some pictures but can't work out how to do that yet. Relay is a srd-05vdc-sl-c

[daniel herring]

http://www.ebay.co.uk/itm/8-Channel-Relay-Module-Board-5V-Active-Low-for-Arduino-PIC-AVR-MCU-DSP-UK-/261844123887?hash=item3cf72040ef:g:zqQAAOSwPhdVJmKv

Product link instead of photos.

[Toby Catlin]

They are rated for AC250V 10A and a 100 watt light bulb would use about half an amp so there is plenty of over head. It also looks like those black chips are optoisolators which insulate the relays from the 5v side of the circuit, ie arduino. This is a double layer of protection as the relays are very unlikely to fail in such a way to pass mains voltage back. The main danger here is touching any of the screw terminals while live or any exposed wires that go into the terminal block. As long as everything is connected properly and in a case it will be safe for switching lamps etc.

Of course if you have any doubts then get a qualified electrician to check it over before powering it up. I am no mains expert but I can confirm this board is designed for switching mains voltages at a rating within range of what you want to do.

toby

On 9 February 2016 at 21:21, daniel herring <djherr...@gmail.com> wrote:

http://www.ebay.co.uk/itm/8-Channel-Relay-Module-Board-5V-Active-Low-for-Arduino-PIC-AVR-MCU-DSP-UK-/261844123887?hash=item3cf72040ef:g:zqQAAOSwPhdVJmKv

Product link instead of photos.

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[daniel herring]

Thanks Toby. Everything I looked at said the same but they are so tiny that I couldn't believe it really. Currently looking into openhab on a Pi to run it. I keep going backwards and forwards between uno or pi. Think openhab adds a lot so currently with pi. I am sure I will decide I need more GPIO tomorrow and try and add an uno in somewhere as well.

Dan

[Toby Catlin]

Thats the crazy thing about electricity. High voltages at very low amps are safe. Like the van de graff generators I had in school are millions of volts at very low amps. They cause a spark but nothing else. It is the amps that kill. Most mains cable is rated at 13amps so you think that is thickness of wire inside the relay and it might become more realistically sized.

Sounds like the best option is a Ardiuno interfaced with a Pi or an Arunion Yun.

t

On 9 February 2016 at 22:43, daniel herring <djherr...@gmail.com> wrote:

Thanks Toby. Everything I looked at said the same but they are so tiny that I couldn't believe it really. Currently looking into openhab on a Pi to run it. I keep going backwards and forwards between uno or pi. Think openhab adds a lot so currently with pi. I am sure I will decide I need more GPIO tomorrow and try and add an uno in somewhere as well.

Dan