relay modules

[salomonander]

hey
i need to fit 5v controlled relays into my mixing desk channels. they will be controlled via a arduino system.
i have found a few products with vastly different price tags.
there are the expensive modules made by a company called pedalsync:
http://www.kaom.com/MV_57_Logic_Controlled_Relay_Bypass_Module_p/module_001.htm

im sure they are great. but not cheap at all. im wondering if a product like this would be any worse:
http://www.ebay.com/itm/New-1-Channel-5V-Relay-Module-Shield-for-Arduino-ARM-PIC-AVR-DSP-SRD-05VDC-SL-C-/280890946801?pt=LH_DefaultDomain_0&hash=item416667b4f1

..costs a fraction and does everything i need it to (i just need one pole). im just wondering if i have to watch out because of clicks or any audible downsides of the cheap modules. if there are none it would be a no-brainer and id go for the cheap versions.

thanks a lot

 

[salomonander]

..or better even these boards for non smd:
http://www.ebay.com/itm/1-channel-Relay-module-5V-relay-extension-board-for-MCU-development-1pcs-/160863276260?pt=LH_DefaultDomain_0&hash=item257432cce4

 

[salomonander]

PS: can i  get replacement relays in this format? never seen this relay size before

 

[Brian Roth]

Do you REALLY need to be switching 10 Amps of current?  Power relays have totally different contacts compared to low-level signal relays.

Bri

 

[salomonander]

no. these will basically be audio mute switches. i dont know too much about the different forms of relays ...not really a tech. but i do need a low profile relay board that is triggered by 5v

 

[salomonander]

i guess  this would be a better onet then (relay looks standard to me at least

http://www.ebay.co.uk/itm/DPDT-Signal-Relay-Module-24Vdc-TAKAMISAWA-RY24W-K-Relay-Has-Assembled-/130666441398?_trksid=p5197.m1992&_trkparms=aid%3D111000%26algo%3DREC.CURRENT%26ao%3D1%26asc%3D14%26meid%3D1281835936345345612%26pid%3D100015%26prg%3D1006%26rk%3D1%26

just dont know if it will fit in the modules. if anyone knows of anything smaller and affordable please let me know

 

[Brian Roth]

After taking a quick look at one of the Arduino spec sheets, It looks like the digital outputs are rated for 40 mA, and thus can directly drive one of these:

http://www.mouser.com/ProductDetail/Panasonic-Electric-Works/TQ2-5V/?qs=sGAEpiMZZMs3UE%252bXNiFaVCLW1ZA8WQBLGF3Vwl4YaEE%3d

If the 40 mA drive spec is correct, all you'll need is to add a snubber diode across the relay coil, and then mount those two components onto a small piece of perf board.

Bri

 

[salomonander]

thanks
yes. thats a good idea. problem is i need to mount the relay somehow. id need like a tiny relay breakout pcb (is there such a thing) with mounting holes or maybe i should look into relay sockets?

 

[Brian Roth]

(Note:  the photo of the relay shown in the Mouser link I posted is apparently for a 4P relay.) 

The 2 pole Panasonic relays are on standard DIP spacing, although a 10-pin DIP socket is not ultra-common, like an 8 or 14 pin.

Bri

 

[sahib]

Jacob,

Those boards are not really suitable. Check your PM.


Brian,

I would not dare to try to teach you how to suck eggs but driving relays directly from the output of a micro is not really a good idea.

However, Jacob has 24 to 32 channels of relay drive and it would not be practicle to drive them all directly.

 

[Brian Roth]

I had noticed that the output port specs for several of the Arduino boards I glanced at claim they can source/sink 40 mA, while the little 5V panasonic relay is spec'ed for 28 mA current draw.  Perhaps if every output port was sourcing/sinking at once, the MPU chip will run too hot?  I dunno...never worked with an Arduino and ASSumed the output pins had some sort of internal buffering in order to meet the 40 mA spec.

Bri

 

[Rochey]

We have basic relay pcb's at expat audio.


I normally use 3.3v to switch 12v omron relays.


/R

 

[Rochey]

I had noticed that the output port specs for several of the Arduino boards I glanced at claim they can source/sink 40 mA, while the little 5V panasonic relay is spec'ed for 28 mA current draw.  Perhaps if every output port was sourcing/sinking at once, the MPU chip will run too hot?  I dunno...never worked with an Arduino and ASSumed the output pins had some sort of internal buffering in order to meet the 40 mA spec.

Bri

Hello Brian,

Logic chips or basic transistors that can source relay-level current are typically made in a silicon geometry that's much larger than whats used for micro controllers.
Microcontroller, and other processors typically have their IO focussed on switching speed, rather than bulk current delivery.
In additional, microcontrollers don't normally take very well to the back EMF created by relays when they switch off.

I'm sure you could run the relay direct for a prototype, but I would be concerned with the reliability.

In addition, most micro's are moving to a 3v3 IO rail. I don't know of too many relays that take 3V3 as their switching voltage.

Cheers

Rochey

 

[audiomixer]

Hi salomonander,

I use an arduino to control audio in my mixer project using fets and an optocoupler arrangement. have a look here if you are interested.

http://audiomixer.wordpress.com/2012/04/19/control

this post shows the control voltages for the mute switch, I have the mute switch arrangement somewhere..... just can't find it right now, based on a douglas self design....
basically its a click free mute / selection, no relays, dedicated control power supply....


cheers,

Michael

 

[Brian Roth]

I did make several comments re. a "snubber" diode across the relay coil......that seems typical for any type of circuitry requiring a relay.

Perhaps I need to read a bit more about the chip used for the Arduino, since 40 mA source/sink current per pin does indeed seem FAR more than what a typical uP can provide.

The boards I was looking at are 5VDC powered, vs 3.whatever used in "modern" uP's.

Bri

 

[Rochey]

Great stuff Brian!

share what you learn, and let me know if there's anything I can help with.

Cheers

Rochey

 

[Brian Roth]

I did some digging, and found this spec sheet from Atmel, the maker of various chips used for Arduino gizmos.

http://www.atmel.com/Images/doc2545.pdf

Goto (lol...Olde BASIC instruction code)  page 303 of the PDF, where I see the (in)famous 40 mA/pin  AND 200 mA for the entire package.  I ASSume the other uP chips used in Arduino apps have similar specs.

Sooooooooooooo.....even those little Panasonic relays that I mentioned will draw too much current if every one was sourcing/sinking current at the same time.

My goal/objective was to try to assist the OP in his quest for a KISS solution, and alas...some sort of buffer will be required to drive the relays.  I guess the relay buffers could be built onto a "shield card" (using the Arduino terminology), and then the spaghetti of wiring would go from there to the individual relays (with snubber diodes across the coils, close by each relay) within the audio device.

Bri

 

[salomonander]

hey guys

thanks for all your replies. i think ill just breadboard a liitle transistor driven board.

 

[APEX JR.]

Salomonader...

If you haven't already found the relays I have these in stock at $1.50ea
http://www.omron.com/ecb/products/pry/111/g5v_2.html

Steve @ Apex Jr.

 

[Rochey]

Steve,

I looked at those ones for my modules... At 500mW they are power hungry little puppies!

I used the omron g6k-2p, which are lower power (but more $$$).

I'm about to redesign the modules and wondered which you think I should choose?