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Topic: How to power 16 channel relay (Read 12312 times) previous topic - next topic

scubieman

I want to buy a 16 channel relay. According to specs it says it needs 12v for the relay to energize. I noticed the arduino uno I am using has max output of 5v. How do I power this so the relays work?

Here is the link..... http://www.amazon.com/SainSmart-16-CH-16-Channel-Relay-Module/dp/B0057OC66U/ref=sr_1_1?ie=UTF8&qid=1403101563&sr=8-1&keywords=16+channel+relay

MarkT

That's not the datasheet...

It looks like it has 16 opto isolators so it takes 16 signals plus ground from the
microcontroller and a 12V supply (several amps probably) to power the relays.

http://www.sainsmart.com/arduino-compatibles-1/relay/16-channel-relay/16-channel-12v-relay-module-for-pic-arm-avr-dsp-arduino-msp430-ttl-logic.html
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johnwasser

Looking up the relay model number: "SRD-12VDC-SL-C" it turns out the the 'L' in 'SL' means the coil draws 0.36 W.  If that 'L' were a 'D' it would mean 0.45 W.

0.36 W at 12 V is 0.030 A (30 mA). 30 * 16 = 480 mA so your 12 V supply should provide at least 500 mA just for the relays.

The LEDs are powered by a 5V regulator running off the 12V supply so you probably need to add at least another 160 mA for those.

12 V 750 mA would probably be sufficient but  12 V 1 A would have more margin.
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jackrae

The unit signal inputs drive directly from the arduino 5 volt signals (your linked web blurb says so).  Power for the relays and onboard components comes from your external 12 volt supply unit.

scubieman

so where do I get the 12v from? If I power board using a 12v 1  amp power supply will that work?

johnwasser


so where do I get the 12v from? If I power board using a 12v 1  amp power supply will that work?


Yes.
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willytwo

I just bought the 16 channel relay board too.
I see there are 5v and ground pins next to the 16 channel pins.
I'm assuming that I should plug the 5v and ground from my Arduino into these terminals as well.
Am I correct?
Or are they power out to the Arduino board?
It sucks that there is no documentation for this board.

willytwo

I just bought the 16 channel relay board too.
I see there are 5v and ground pins next to the 16 channel pins.
I'm assuming that I should plug the 5v and ground from my Arduino into these terminals as well.
Am I correct?
Or are they power out to the Arduino board?
It sucks that there is no documentation for this board.

woodygb

#8
Dec 19, 2014, 07:42 pm Last Edit: Dec 19, 2014, 07:44 pm by woodygb
I just bought the 16 channel relay board too.
I see there are 5v and ground pins next to the 16 channel pins.
I'm assuming that I should plug the 5v and ground from my Arduino into these terminals as well.
Am I correct?
Or are they power out to the Arduino board?
It sucks that there is no documentation for this board.
http://www.sainsmart.com/arduino-compatibles-1/relay/16-channel-relay/16-channel-12v-relay-module-for-pic-arm-avr-dsp-arduino-msp430-ttl-logic.html

Scroll down to where it says....

Quote
Click to Download the Manual

michinyon

It appears from the schematic that the device creates its own 5V supply from the 12V supply.

If this is so, it's not obvious why you would be connecting the 5V connection to the Arduino.

Maybe you can use it to power the Arduino.

And as for "click to download the manual",   if you actually do this,  there is no manual.

Some sort of PCB track image,   and a schematic,  which is rather confusing.   The  control inputs seem to be active low,   which is not what you would expect from the description.

cppdanny

You could resolve the problem by buying a 5v version of the board like
i did. The 1/2/4/6/8 Channel 5V Relay Board Module Optocoupler LED for Arduino PiC ARM AVR
There is also a 16 channel selectable there too. The link follows.

http://www.ebay.com/itm/1-2-4-6-8-Channel-5V-Relay-Board-Module-Optocoupler-LED-for-Arduino-PiC-ARM-AVR/172433598201?_trksid=p5713.c100041.m2061&_trkparms=aid%3D333008%26algo%3DRIC.MBE%26ao%3D1%26asc%3D20140109102600%26meid%3Dbf31768fe3f144469dc93004ea41281a%26pid%3D100041%26rk%3D2%26rkt%3D35%26sd%3D191990594110

756E6C

#11
Mar 01, 2017, 08:56 am Last Edit: Mar 01, 2017, 09:02 am by 756E6C
I would first try connecting only 5V and 1 IN pin to Arduino and see if that works, you may only need GND if you want to power Arduino from the relay board.
NOTE: You need to pull the OUTPUT pin LOW to energize the relay.

rudy_albachten

#12
Jun 16, 2019, 06:18 pm Last Edit: Jun 16, 2019, 06:23 pm by rudy_albachten
This is really old but still shows up when searching the topic.

The relay board requires 12V for the relays and generates it's own 5V for the control logic.

The 12V supply needs to be at least 640mA for the relay board if all relays can be on at the same time (plus the current used any external circuitry powered by the 5V regulator on the relay board).

The +5V terminals on the relay board are outputs - never connect 2 regulated power supplies together.

The inputs have pullup resistors to the on-board 5V and are activated by pulling them down to ground.

There are 2 ways to use this board depending on whether you want to power the arduino from the relay board's 5V 3A regulator.

Option 1:

   The simplest way to connect this board to an already powered arduino is to ignore the 5V connection.

   Only connect Ground and the relay inputs to the arduino.

   The arduino and the relay will have independent 5V supplies and the difference will cause a micro current through the pullup resistor when the arduino drives a high value to the relay input.

   When the arduino pulls down the input, it will sink a small ~4mA current to activate the optoisolator input stage and activate the relay.

   If using a 3.3V controller, you can use a 1n914 (1n4148 is the same) diode between the controller and the relay input (the cathode end is marked with a band and goes on side toward the arduino)

Option 2:

   Power the arduino from the 5V output on the relay board.

   Connect +5V GND and the logic level inputs.

   Don't connect any other power source to the 5V arduino.

   The arduino can use almost all of the 3A rated output of the regulator.

Wawa

Pin current is AFAIK 2mA (5volt, 1.2volt opto LED, 1.8volt indicator LED, 1k resistor).
The diode for 3.3volt logic is not needed, because of the ~3volt threshold of the two LEDs in series.
16-channel boards have a design fault. Optos, but no opto isolation.
Leo..
 

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