Using relais with thermal pads

Hello All,

I am a noobie when it comes to electronics. I want to make a little greenhouse box for my seedlings with thermal pads at the bottom. I want to use my arduino to control the thermal pads, for turning them on and off.

The problem is I don't know how to connect the cable to the relais. I got a relais on my arduino, should I open the cable of the thermal pads and place them in the relais, but how will I get my cable to the plug?

This is the drawing I made of the thing I want to accomplish:

These are the thermal pads and the relais I am going to use:
https://nl.aliexpress.com/item/2016-Hot-Sale-Useful-US-Plug-110V-Pet-Reptile-Brooder-Incubator-Heat-Heating-Mat-Warm-Pad/32763451081.html?isOrigTitle=true

https://nl.aliexpress.com/item/1pc-1-Channel-5V-Optocoupler-Driver-Relay-Module-High-Level-for-Arduino-top-quality/32638202870.html?ws_ab_test=searchweb0_0,searchweb201602_1_10065_10068_433_434_10136_10137_10138_10060_10062_10141_10056_10055_10054_128_10059_201_10531_10099_10530_10103_10102_10096_10052_10053_10050_10107_10142_10051_10106_10143_10526_10529_10084_10083_10080_10082_10081_10110_10111_10112_10113_10114_10037_10078_10079_10077_10073_10070_10122_10123_10124-10531,searchweb201603_3,afswitch_1,ppcSwitch_5,single_sort_0_default&btsid=3c3ce1c3-c3f5-4ee6-8164-b340206618a3&algo_expid=3d62fc7c-a129-46ea-be3e-3c0d68649955-4&algo_pvid=3d62fc7c-a129-46ea-be3e-3c0d68649955

Thanks in advance :slight_smile:

Greetings,

0xygen2

Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.

Your image did not take, but the forum instructions will show you how to attach your file.

Tom... :slight_smile:

TomGeorge:
Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.

Your image did not take, but the forum instructions will show you how to attach your file.

Tom... :slight_smile:

I changed it to a URL, I thought it might take a gyazo links as img. Hope this clearifies my project, please don't mind my mad paint skills.

Because you are using 115V heating pads, you need a PCB to mount the relay or relays onto, designed so that there is a safety gap all the way around the components. You could either mount 115V US-style sockets on the PCB, or cut the plugs off the heating pads and wire them onto connector blocks soldered into the PCB.

The relays themselves need to be rated for 125 VAC, or preferebly 250VAC, and the relays will need to be able to open & close using the 5V low-current signals available from the Arduino.

If you can't find such a relay, you will need to create, say, a 12V DC supply, and use transistor to drive the relays, so that you do not place too high a load on the Arduino. I use Farnell a lot for sourcing components:

http://ie.farnell.com/webapp/wcs/stores/servlet/Search?pageSize=25&st=relay+5V&catalogId=15001&categoryId=700000006250&langId=353&storeId=10163

and you'll get everything else there that you need too.

Bon chance!

PS You need to be sure you understand all the safety implications of using 115VAC.

Or get one of these
http://www.powerswitchtail.com/Pages/default.aspx

The AC wiring color codes are slightly different in different countries. Find out which side of your AC outlets and plugs is Neutural and the other side is Hot/Load. Run a power cord from the outlet to your Arduino which can carry enough wattage for the sum of the heaters. Connect the Neutural side of the power cable to the Neutural side of all of the heaters. Connect a wire from the Hot side of the power cable to the Common side of each relay. Connect the Hot side of each heater to the NO (Normally Open) or NC (Normally Closed) side of its assigned relay (your choice).

johnwasser:
The AC wiring color codes are slightly different in different countries. Find out which side of your AC outlets and plugs is Neutural and the other side is Hot/Load. Run a power cord from the outlet to your Arduino which can carry enough wattage for the sum of the heaters. Connect the Neutural side of the power cable to the Neutural side of all of the heaters. Connect a wire from the Hot side of the power cable to the Common side of each relay. Connect the Hot side of each heater to the NO (Normally Open) or NC (Normally Closed) side of its assigned relay (your choice).

NC is that the thermal pads are normally not working unless the arduino gives them the command right? Thanks a lot for your help guys :).

NC is normally closed. Closed with no power. NO is normally open. Open circuit with no power. NO requires power (signal from Arduino) to close and complete the circuit.

adwsystems:
NC is normally closed. Closed with no power. NO is normally open. Open circuit with no power. NO requires power (signal from Arduino) to close and complete the circuit.

NC is that the circuit is closed so the electricity can move trough the circuit right? Then I thought wrong in my post above.

CrossRoads:
Or get one of these
http://www.powerswitchtail.com/Pages/default.aspx

This perfectly answers the original question and deserves a comment.

"deserves a comment" ?? Do you mean karma? Or something else?