Project: 8 channel Relay Box

This is a 8 channel relay box that the input connect to a controller allow it to control large loads like home appliances.

I'm using this relay box for a snooker centre to control snooker table lamps. The lamps consists of 6 pieces 20W and 3 pieces 10W fluorescent lamps, total of power consumption is 150W per table.

Material:
PVC BOX
DIN Rail
2A 12 DC adapter
Omron MKS2P relay x 8
On/Off Swith x8
Relay Socket
ULN2803 IC
18pin Swiss machined socket
PCB with copper hole
Pin Header connector
Wire/IDE cable or Floopy drive cable
Key Switch

Finish product shows 10 on/off switch. I'm using only 8 of them, 2 of them reserved for future use.



Block diagram



Connection diagram



The relay is control by an ULN2803 line driver. As shown in figure below, I'm using Swiss machined socket for the ULN2803 since the ULN2803 can generate heat & require more current on it especially on pin9 (Gnd), but I agree the best thing is a solid soldered connection.


To turn on relay manually, on/off switch must connect between the output of ULN2803 and relay coil. See figure below on how to adding on/off switch and indicator to the circuit. This is very useful when the controller is not able to control the relays while still want to turn on the lights.



Figure below shows 10 units on/off switch fixed to the cover, I'm using only 8 of them, the other two is reserved for future use. A key switch is use to prevent manually turn on the relay.



More pictures and instruction available at
http://ediy.com.my/index.php/projects/item/43-8-channel-relay-box

 

This project while simple its function seems to be well documented. I can't make out what role the Arduino plays in this project. I also could not locate the source code for the project. If it is buried in a link then I totally missed it.

hgmjr

 

The Arduino is do nothing here, it use to show that the relay box must connect to the controller and allow it to communicate with the controller.

You don't have to use an Arduino, you can use any other device as a controller.

I think I should remove the Arduino from the picture. Thank you for your feedback.

 

I'm first time posting article in this forum. May be I had missed out something.

I though I want to upload all the pictures to this project, but this fourm limited me to upload only 6 pictures. Is there a way that I can upload more pictures.

 

Are the switches SPST (single pole single throw) type rather than momentary type? If so, then it seems you don't need the Arduino or the ULN2803 and your project is really just a key switch, eight lighted SPST switches, and eight 12 volt relays, is that correct?

 

I'm using the Arduino as an example of controller, you can use any device as the controller.

Actually you need the ULN2803 since most of the controller cannot connect directly to the Relay. Another reason is the controller is using 5V and the relay is using 12V.

 

Your project presentation then is a switch controlled eight channel relay box which includes a ULN2803 interface for a microcontroller. Is that correct? If so, it would seem that any individual switch left in the "on" position would energize its associated relay and over-ride any microcontroller control of that relay channel. And so, if a user wants to control all of the relays using a microcontroller he/she would have to make sure all of the switches were left in the "off" position, yes?

Very nice job on the relays and enclosure...

 

Yes, you are correct. The purpose for the on/off switch is for emergency use, user can manually turn on the relay when the controller is not functioning.

I'm using this relay box to control snooker lamps, when the snooker lamps is turn on, the rate counter is start to count money Sometime the snooker lamps including the snooker tables (everyday need to clean and the environment is very dark) require to maintenance, therefore it must turn on manually (provided the key switch must turn on) without start the rate counter.