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Topic: 2x Arduino: One as a power supply, One actioning 4 relays (Read 14097 times) previous topic - next topic

3AgL3_DeeJay

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larryd

There still has to be a common ground from the Arduino to the ULN2803.
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3AgL3_DeeJay


There still has to be a common ground from the Arduino to the ULN2803.

I won't forget that.

I'm going in a few hours to a store to buy a couple of ULN2803s.
Test them a little, put together a scheme and come back with the results. :D
Thanks again!
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larryd

Do you understand how the current will flow in this schematic?
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3AgL3_DeeJay


Do you understand how the current will flow in this schematic?

Yes! It's easy now that i saw the schematic. Thanks!!!

I went to the store but they didn't have the 2803 on the stock. I have to wait a few more days to get it. :(
Until then, i will do the final scheme. And this time, right. :D
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3AgL3_DeeJay

I finished the schematics for the LEDs. I put the 2803 in the right way now...
But i don't know how to do the Relay connections. :(
My relays have to be always connected to a +5V line and a GND. Then i have to send a "HIGH" signal through the INT pin to switch the relay.
Since the 2803 only works by "switching" the GND line, i don't know how to use the 2803 with the relays.

I searched online for some examples, but all of them used the 2803 like this: power the relay coil from a +5V line, then run the GND line through the 2803 (like the photo from the attachment). And i can't use that... :(
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larryd

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3AgL3_DeeJay


Show us a link to the relay you are using.


I don't have a link. I purchased them from a local store.
But here are some photos of the exact model i have.
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larryd

Do you think this is the same?
http://www.aliexpress.com/store/product/2-Channel-Relay-Module-5V-for-PIC-ARM-AVR-DSP-wholesale-and-retail/707291_499450487.html
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3AgL3_DeeJay


Do you think this is the same?
http://www.aliexpress.com/store/product/2-Channel-Relay-Module-5V-for-PIC-ARM-AVR-DSP-wholesale-and-retail/707291_499450487.html


Yes! That's the one...
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larryd

If you only have 4 realys to drive on the Adruino, don't use the 2803.
jumper JD-Vcc to VCC, Arduino +5 to relay VCC, arduino GND to relay GND, Arduino o/p pin to IN1 and IN2.
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3AgL3_DeeJay


If you only have 4 realys to drive on the Adruino, don't use the 2803.

In this stage a have only 4 relays. The finished project will have at least 10 relays...


jumper JD-Vcc to VCC, Arduino +5 to relay VCC, arduino GND to relay GND, Arduino o/p pin to IN1 and IN2.

That's how i used it so far...
But when i turn them on, i don't have 5V on Ardiono +5V pin anymore...
That's why i want to supply power for them from an external power supply (EPS).
So it will go something like this: connect the relay's VCC to the EPS +5V, the relay's GND to the EPS GND, and the INT1 and INT2 to the Arduino digital pins...
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larryd

Connect the 2803 o/p to IN1 or IN2  then External +5V (not the Arduino +5) to Relay VCC/JD-VCC.
In this case a HIGH on the o/p of the Adruino will close the contacts.

Of course Arduino GND to relay GND to external supply GND.

With 10 relays use the 2803.
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3AgL3_DeeJay


Connect the 2803 o/p to IN1 or IN2  then External +5V (not the Arduino +5) to Relay VCC/JD-VCC.
In this case a HIGH on the o/p of the Adruino will close the contacts.
Of course Arduino GND to relay GND to external supply GND.
With 10 relays use the 2803.


After i saw your message, this is what i understand (keep in mind that i'm from Europe :D ):
- Connect 2803 o/p to IN1
- Connect EPS +5V to Relay VCC
- Connect ALL the GND line together
-> And what about the Arduino pin? Where to put that?

See the schematic:
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larryd

Arduino O/P Pin 31 to 2803 pin 1
2803 pin 18 to relay IN1 or IN2

Relay JD-VCC to relay VCC to EPS +5V to 2803 pin 10.
Relay GND to Arduino GND  to 2803 pin 9.
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