Mega voltage question

Using Arduino General Electronics
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So I have a configuration consisting of 3 8-relay boards, with a total of 24 relays. I have a light switch sketch that turns a switch on and off from an Android app.

I can turn on 8 relays at once on 1 relay board, however, when I start turning on relay 9, 10 and so forth on relay board 2, it seems I run out of juice - all the relays turn off without me turning them off. I did a forum search to find a solution but nothing specific to my scenario. I would like to be able to power on all 24 relays at once and assuming I would need an external PS. What can I do to rectify my problem?

I purchased this hoping it would resolve the issue, but the problem still exists when the Arduino is powered with this PS.

2

How about some info on the relay board?

3

650ma of current is not much... how much current does each relay consume? (Use a multimeter set to ohms and measure)

Sounds like the regulator is dropping out.

4

you can usually power the relays with external power, then just send an "signal" from the Arduino...

5

CrossRoads:
How about some info on the relay board?

Sorry about that, here you go! This is what I purchased, and attached is a schematic.

relay.png
relay.png1071×708 56.4 KB

6

Qdeathstar:
you can usually power the relays with external power, then just send an "signal" from the Arduino...

True, is there a recommended board PS for the relays I posted? The arduino will still need to send 5 v to the relay switch right? All 24 on at the same time.

7

Datasheet here
http://www.datasheet-pdf.com/datasheet/Songle/720556/SRD-05VDC-SL-C.pdf.html
says the coils need 70mA each.
8 x 70 = 560mA.
3 boards = 1680mA.
You need a bigger 5V supply for the relay boards to connect to JD-VCC.
Do not install the jumper that connects VCC to JDVCC.
Connect board's GND to Arduino GND.
http://www.dipmicro.com/store/DCA-0520

8

CrossRoads:
You need a bigger 5V supply for the relay boards to connect to JD-VCC.

Is there one that you recommend?

CrossRoads:
Do not install the jumper that connects VCC to JDVCC.

Ok I just want to make sure I understood correctly, attached is a picture of my board, are you saying to remove the VCC and Ground which I currently have connected to my Arduino in the IN1-8 row and use the JD-VCC and ground where the jumper is to power the board from an external source?

CrossRoads:
Connect board's GND to Arduino GND.
Switching DC Wall Power Adapter 5V / 2A - dipmicro electronics

Will this resolve my entire issue? Or will I still need the external PS for the relays.

IMG_4871.JPG
IMG_4871.JPG2448×3264 1.24 MB

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Connect GND from all cards next to In1-2-3-4...to Arduino Gnd.
Connect dipmicro 5V/2A supply to GND/JD-VCC. Remove the yellow (orange) jumper.

External supply is needed. The relay coils need more current than you can get from the Arduino 5V supply.

10

CrossRoads:
Connect GND from all cards next to In1-2-3-4...to Arduino Gnd.
Connect dipmicro 5V/2A supply to GND/JD-VCC. Remove the yellow (orange) jumper.

External supply is needed. The relay coils need more current than you can get from the Arduino 5V supply.

The link you gave me shows a 2.1mm plug, how am I wiring that up to the relay boards to JD-VCC?

11

Plug into something like this, split out to three boards.

12

CrossRoads:
Plug into something like this, split out to three boards.
http://www.pololu.com/product/2449

Thank you for all your help CrossRoads. I wanted to recap and make sure I got everything:

  • Remove jumper and connect external PS to JD-VCC. Nothing connected to GND and VCC. (or do I connect the GND to the PS?)

  • Leave GND on the row of pins with IN1-8 connected to the Arduino.

  • The PS I purchased from Amazon is that good enough to power the Arduino?

I just want to confirm I'm doing it right before I burn my house down XD

13

Connect PS to JD-VCC and GND.
Leave GND connected to Arduino - use a meter and make sure the two GNDs on the relay card are connected.
Amazon supply looks to be 9VDC, 650mA, good for Arduino use.

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