sebastienb
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SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Channel

Mon Feb 11, 2013 5:30 am

Hi guys,
I'm new here, and just getting started with the Raspberry Pi. I've followed a tutorial and was able to trigger some led's with little code. I was looking to purchase a relay board to use with the gpio ports but I need some suggestions as to which one would be best.

Option 1
SainSmart 8-Channel 5V Relay Module for Arduino DSP AVR PIC ARM
http://www.amazon.com/gp/product/B0057OC5WK/ref=ox_sc_act_title_4?ie=UTF8&psc=1&smid=A28PCZ3GGXGBES


Option 2
SainSmart 8-Channel 5V Solid State Relay Module Board for Arduino Uno Duemilanove MEGA2560 MEGA1280 ARM DSP PIC
http://www.amazon.com/gp/product/B006J4G45G/ref=ox_sc_sfl_title_2?ie=UTF8&psc=1&smid=A10EAPE4CAYC9P

From what i've read on the board, option 1 works but requires a little more power to trigger all the relays (using an additional power supply). Since option 2 uses electronic relays instead of mechanical ones would it be simpler to use and able to be powered by just the Raspberry Pi ?

Thanks for the help

pjc123
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Chan

Mon Feb 11, 2013 12:37 pm

sebastienb wrote: From what i've read on the board, option 1 works but requires a little more power to trigger all the relays (using an additional power supply). Since option 2 uses electronic relays instead of mechanical ones would it be simpler to use and able to be powered by just the Raspberry Pi ?
I can speak for option 1 because I am currently using it. The specs on Amazon are incorrect. With the necessary relay card power supply input of 5V (3.3V does not supply enough voltage) the relay card requires only around 1.5ma from each GPIO port to trigger each input circuit, which in turn triggers the relay. However, the coil of each relay requires about 60ma to turn on the relay. Where they got 15 – 20ma driver current I have no idea (Maybe they forgot the decimal point). So, yes, if you turn on a lot of relays simultaneously, you would need an external power supply like I am using, especially if the pi is using power hungry USB devices. Also, a transistor or other similar device is necessary to safely connect the GPIO pins to the relay card input. In addition, the inputs are active low. Also, If you look at the specs of each card, you can also see that the solid state version output is only rated at 0.1 - 2 Amps, while the other one is rated at 10 Amps. I don't know anything about the solid state version of this board, but even if it takes a lower total current (trigger plus coil current), be careful to check the schematics of the card to insure it can safely be connected directly to the pi without additional separation/protection circuitry.
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klricks
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Chan

Mon Feb 11, 2013 1:43 pm

You would need level converters between the GPIO pins and the relay board
Something like this:
http://www.amazon.com/SparkFun-Logic-Le ... +converter

Note if you select each link in your post and then click the URL button your links will be click-able.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Stretch w/ Desktop OS.

pjc123
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Chan

Mon Feb 11, 2013 2:32 pm

klricks wrote:You would need level converters between the GPIO pins and the relay board
Something like this:
http://www.amazon.com/SparkFun-Logic-Le ... +converter

Note if you select each link in your post and then click the URL button your links will be click-able.
Or just a simple 7 cent transistor will suffice as I am using:

http://www.raspberrypi.org/phpBB3/viewtopic.php?t=19222
My Raspberry Pi Project Page:
https://www.flaminghellmet.com/launch/

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abishur
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Chan

Mon Feb 11, 2013 2:56 pm

I'm using the solid state version of their card and like it a lot. For example, the SSR version uses the GPIO as outputs (so you trigger the card by writing a one) whereas the non-SSR version uses them as ground meaning you have to write a zero to them to trigger the relay. Additionally, if you use the non-SSR version you need to make sure that you have things set right so you're not trying to feed 5V into one of the GPIO (yes it goes through an LED first, but it's bad practice to rely on LEDs to provide the necessary voltage drop to make it not damage things ;-) )

All that said, either one *will* work sufficiently. You just need to take a couple extra steps with the non-ssr version :-)
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pjc123
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Chan

Mon Feb 11, 2013 3:15 pm

abishur wrote:I'm using the solid state version of their card and like it a lot. For example, the SSR version uses the GPIO as outputs (so you trigger the card by writing a one) whereas the non-SSR version uses them as ground meaning you have to write a zero to them to trigger the relay. Additionally, if you use the non-SSR version you need to make sure that you have things set right so you're not trying to feed 5V into one of the GPIO (yes it goes through an LED first, but it's bad practice to rely on LEDs to provide the necessary voltage drop to make it not damage things ;-) )

All that said, either one *will* work sufficiently. You just need to take a couple extra steps with the non-ssr version :-)
I was hoping someone would reply about the SSR version; that's good to know for future builds. It was not available at the time I ordered mine, although it would not have worked for my application anyway, as I need between 2 -3 Amps per relay.
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abishur
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Chan

Mon Feb 11, 2013 5:15 pm

pjc123 wrote: I was hoping someone would reply about the SSR version; that's good to know for future builds. It was not available at the time I ordered mine, although it would not have worked for my application anyway, as I need between 2 -3 Amps per relay.
Ah that is an important difference as well. The SSR version has a max load of 2A per relay, whereas the non-SSR version can handle up to 10A!
Dear forum: Play nice ;-)

sebastienb
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Chan

Mon Feb 11, 2013 10:36 pm

Thanks Guys, I went with the non SSR version, getting it on wednesday :D . Going to start setting up the web control part of it today and test with led's

ryanjennings
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Joined: Mon Jul 09, 2012 4:14 pm

Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Chan

Thu Feb 21, 2013 1:11 pm

I haven't used either yet, but have both to try at some point. Just wanted to add to the conversation that the SSR version won't switch DC.

pjc123
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Chan

Thu Feb 21, 2013 2:48 pm

ryanjennings wrote:I haven't used either yet, but have both to try at some point. Just wanted to add to the conversation that the SSR version won't switch DC.
Good point. I had originally looked into using individual SSR's that control high current DC loads (high being around 10 amps), but they were prohibitively expensive, so I settled on the Sainsmart mechanical relay version.
My Raspberry Pi Project Page:
https://www.flaminghellmet.com/launch/

fixedd
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Chan

Wed Mar 27, 2013 4:53 am

Just wanted to put this out there... I laid out a board to drive the non-SSR version using transistors to pull the input pins to ground. The schematic/layout is available at https://github.com/fixedd/RPi_SainSmart_Interface

FunkyE9th
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Chan

Wed Apr 03, 2013 2:41 am

Hi,

Are the relays DPDT? If not, anyone know where I can get an 8-channel DPDT relay boards?

Thanks!

OutsourcedGuru
Posts: 35
Joined: Mon Jun 19, 2017 11:15 pm

Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Chan

Mon Jul 03, 2017 10:30 pm

It helps to know what these things often are inside the little black box: https://en.wikipedia.org/wiki/Solid-state_relay
(It might be a triac, SCR, MOSFET or transistor.)

A typical transistor-based amplifier by its nature reverses the output (low in, high out) so they're sometimes called an inverter or NOT gate. Often, they're implemented by using a quad-NAND gate chip but putting the same input on a single gate's A and B inputs. So some of these "3.3V-5V logic converter chips" (Pi-to-Aruino) might just be an SN 7400N quad-NAND gate in disguise, with a little clever external wiring.
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SteveSpencer
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Chan

Tue Jul 04, 2017 1:56 pm

fixedd wrote:Just wanted to put this out there... I laid out a board to drive the non-SSR version using transistors to pull the input pins to ground. The schematic/layout is available at https://github.com/fixedd/RPi_SainSmart_Interface
I did something similar with Fritzing, and had some made up by Aisler (who do the Fritzing fab) as a pHAT for ZeroW with a web server in Python. In my case I inverted the logic back, so 0 on the GPIO means relay off, 1 means relay on.
Steve S
No, I can't think of anything funny that won't offend someone if they want it to...

freddyja
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Channel

Sun Nov 26, 2017 1:59 am

I decided on option 2, the SainSmart 8-Channel 5V Solid State Relay Module Board. I'm try to use it with my rpi 3, to control my xmas lights. I attached all the gpio to each channel on the relay, the vcc to the 5v pin and the gnd next to vcc to gnd pin on rpi and have not connected anything to the gnd on relay to the bottom of the channels. But it does not turn on, I'm I doing something wrong, is there a test for the relay

pcmanbob
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Channel

Sun Nov 26, 2017 8:31 pm

freddyja wrote:
Sun Nov 26, 2017 1:59 am
I decided on option 2, the SainSmart 8-Channel 5V Solid State Relay Module Board. I'm try to use it with my rpi 3, to control my xmas lights. I attached all the gpio to each channel on the relay, the vcc to the 5v pin and the gnd next to vcc to gnd pin on rpi and have not connected anything to the gnd on relay to the bottom of the channels. But it does not turn on, I'm I doing something wrong, is there a test for the relay
So you have picked a relay board that is designed to be driven by 5v and uses 5v inputs on the control inputs as well, as its designed for the arduino not the pi.

So you are going to need a separate 5v power supply for the relay board and you are going to have to build an interface to go between the pi gpio and the relay board, because the pi only has 3.3v gpio outputs and not the required 5v.

simple way to prove this relay board is working.

connect 5v power supply to the 2 separate terminals marked vcc and ground then connect the ground from this terminal to the ground at the bottom on the control pins connectors.

now if you connect one of the in pins to the 5v you should see the relay turn on.

Image

if you want help with the interface then I can draw you a diagram for that.
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gordon77
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Channel

Sun Nov 26, 2017 9:04 pm

Is this the same board https://www.amazon.co.uk/SainSmart-8-Ch ... 5WMK4YKA7C?
It says it should work with 2.5v input

pcmanbob
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Channel

Sun Nov 26, 2017 9:20 pm

gordon77 wrote:
Sun Nov 26, 2017 9:04 pm
Is this the same board https://www.amazon.co.uk/SainSmart-8-Ch ... 5WMK4YKA7C?
It says it should work with 2.5v input

from the original link
Input control signal voltage: 0V - 0.5V Low stage (SSR is OFF), 0.5V - 2.5V (unknown state), 2.5V - 20V High state (SSR is ON); SSR Output (each channel); Load voltage range: 75 to 264VAC (50/60Hz); Load current: 0.1 to 2 AMP
but freddyja said it did not work, so I suspect that the 2 resistors on the base of the transistor used to drive the LED & SSR as show in the diagram on the original link are spec'ed for 5v input not 3.3v but as you cant read the values I am only guessing

original link https://www.amazon.com/gp/product/B006J ... APE4CAYC9P
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freddyja
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Channel

Sun Nov 26, 2017 11:07 pm

Yes, please cause I saw a youtube were a guy used a rpi to this exact relay but I did not see a interface. He had a rpi and this relay connect to outlets controlling lights. Thanks

freddyja
Posts: 3
Joined: Sun Nov 26, 2017 1:24 am

Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Channel

Sun Nov 26, 2017 11:57 pm

If it helps I also purchased this from Amazon
https://www.amazon.com/gp/product/B073Z ... UTF8&psc=1
If any of these parts would help, Thanks

pcmanbob
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Re: SainSmart 8-Channel 5V Relay Module VS SainSmart 8-Channel

Mon Nov 27, 2017 1:26 am

First have you tried the test I suggested to prove the relay board works the way I suspect ?

You need to do the testing as I don't have access to your relay board.
Please only ask questions in the forum I will not answer questions sent to me directly via PM
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