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Urgent. Problem in Relay connection

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well

New Member
Hi friends, firstly thanks for your help~

I'm doing a automatic room light controller for my finaly year project. I'm having problem on how to connect the relay on the PCB layout.

Below are some of the diagrams for reference:


schematic diagram of the circuit


PCB layout


PCB front part

Here are some of my quitions:

1. what type of relay should i choose for this project? i'm currently using a 5 pin relay, however, there are only 2 pin slot on the PCB board, how can i connect to it? the requirement for relay is 12V, 200Ω, 2C/O

2. Is it possible that the relay is actually not located on the PCB board above?

3. Please explain to me how the connection as shown in schematic diagram can be done on the PCB board.

Once again thanks for your help. Hope to hear from all of u soon as i really need it urgently. Thanks
 

Sceadwian

Banned
I don't know about anyone else but those images are too small for me to trace anything, my eyes are going cross trying to read it =) Can you post bigger ones?
 

OutToLunch

New Member
a general rule of thumb when laying out a board is to first either know the specific part that is going to be used or know the footprint that is going to be used. There are no such things as two pin relays - you need pins for the contacts and pins for the coil.

Also, Sceadwian is right - I can't read the diagrams - way too fuzzy.
 

colin55

Well-Known Member
The circuit diagram is not large enough and not clear enough. It looks like you can omit the relay contacts from the LDR (conect these together on the PCB) and this means you just need 2 pins (called switch contacts) plus another two pins on the relay that go to the coil. You will need to make sure the light from the globe you are turning on is not detected by the LDR. If this is not possible, you will need a relay with two sets of contacts.
The 2 pins that go to the coil of the relay are taken to the PC board where the diode is identified. The other two pins on the relay are taken to the corner of the board. The two pins to use on the relay are these: the centre pin (if there are three pins in a row) goes to one of the holes (solder-land) on the board. The other pin is the one that creates a circuit when the relay is energised.
 
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ericgibbs

Well-Known Member
Most Helpful Member
Hi friends, firstly thanks for your help~

I'm doing a automatic room light controller for my finaly year project. I'm having problem on how to connect the relay on the PCB layout.

Here are some of my quitions:

1. what type of relay should i choose for this project? i'm currently using a 5 pin relay, however, there are only 2 pin slot on the PCB board, how can i connect to it? the requirement for relay is 12V, 200Ω, 2C/O

2. Is it possible that the relay is actually not located on the PCB board above?

3. Please explain to me how the connection as shown in schematic diagram can be done on the PCB board.

Once again thanks for your help. Hope to hear from all of u soon as i really need it urgently. Thanks
hi,
The relay is mounted OFF the pcb, its on a remote pcb
Its a 12V, 2 pole change over relay, with mains rated contacts.

Run a pair of wires from the two pcb pads near the LDR, [which is required for the light/dark control to the opto] to the remote pcb contacts, say contact set RL1/A

Run a pair of wires from the two pcb pads adjacent to the relay driver transistor to the remote relay pcb coil.

The mains rated lamp wiring will be connected to the pcb on which the relay is mounted, contacts RL1/B

Do you follow OK.?
 
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ericgibbs

Well-Known Member
Most Helpful Member
Thanks for all of ur reply.
much appreciate.
Sorry bout the pictures. I had attach the actually size of the picture here.
Thx
hi,
Did you follow my post.?:)
 

well

New Member
hi,
The relay is mounted OFF the pcb, its on a remote pcb
Its a 12V, 2 pole change over relay, with mains rated contacts.

Run a pair of wires from the two pcb pads near the LDR, [which is required for the light/dark control to the opto] to the remote pcb contacts, say contact set RL1/A

Run a pair of wires from the two pcb pads adjacent to the relay driver transistor to the remote relay pcb coil.

The mains rated lamp wiring will be connected to the pcb on which the relay is mounted, contacts RL1/B

Do you follow OK.?
Ya i'm with you. Helpful information for me. Thanks a lot. Will try it out.
If i get u correct, 2 pairs of wires are connected to one relay on remote PCB? so i should use a five pin or 4 pin relay?
 

ericgibbs

Well-Known Member
Most Helpful Member
Ya i'm with you. Helpful information for me. Thanks a lot. Will try it out.
If i get u correct, 2 pairs of wires are connected to one relay on remote PCB? so i should use a five pin or 4 pin relay?
on a 2 pole changeover there are:
2 pins for the coil; from the drive transistor
3 pins for RL1A contact set; from the LDR
3 pins for RL1B contact set; to the lamp circuit

thats 8 pins.!
 

well

New Member
on a 2 pole changeover there are:
2 pins for the coil; from the drive transistor
3 pins for RL1A contact set; from the LDR
3 pins for RL1B contact set; to the lamp circuit

thats 8 pins.!
I see. Fully understand now. Really appreciate for your help. Thanks a lot. :)
 

ericgibbs

Well-Known Member
Most Helpful Member
I see. Fully understand now. Really appreciate for your help. Thanks a lot. :)
This is an example, contacts are over rated for a small tungsten lamp, but its 240Vac
 

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well

New Member
another question, how to connect wire pair to RL1A since it has 3 pins. Which pin should i attatch for? And is it the same for RL1B contact set? I'm a newbee in electronics.
 

ericgibbs

Well-Known Member
Most Helpful Member
another question, how to connect wire pair to RL1A since it has 3 pins. Which pin should i attatch for? And is it the same for RL1B contact set? I'm a newbee in electronics.
Look at the drawing for the base of the relay you choose.

It will show the contacts as drawn in your posted circuit.

N/C = normally closed when relay not energised and
N/O = normally open when relay not energised.
 
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