Coming Soon: Dual Relay Board Kit

[Chris Savage]

Parallax has a new product coming out based on feedback and requests from our customers. If you ever hada need to control 1 or 2 devices where a relay was required, the Dual Relay Board Kit is just what you need. The kit comes complete with the hardware shown below. Soldering required, but all through hole parts are used.

90154

Once assembled the Dual Relay Board requires a 12V power supply for the relays and a signal and common ground to your BASIC Stamp Module, Propeller chip or other microcontroller output pin for each relay.

90155

12V power for the relays is provided via the terminal block on the top of the board in the above photo. The LEDs indicate a relay is active (ON). The 2x3 header on the left provides ground and signal access to trigger each relay and can accept a standard servo cable such as those commonly used with many of our other accessories. The terminal block at the bottom provides COM, NO and NC connections to each Omron relay, capable of switching 12A @ 250VAC.

The drivers for the relays are simple 2N3904 transistors and can be activated by 3.3V and 5V. Diodes protect the transistors from back-emf and the board includes mounting holes. The dual relay board can also be controlled directly from the output of many sensors, such as our PIR sensor (#910-28027) or (#555-28027). If you have any questions, please reply. These should be available in mid-March.

[davejames]

Mr. Savage - is that 12A really switching current or is it carry current?

[Chris Savage]

Dave,

The datasheet (http://www.parallax.com/Portals/0/Downloads/docs/prod/compshop/400-00052Datasheet.pdf) for the 12A Omron Relay (http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/relay/List/0/SortField/4/ProductID/656/Default.aspx) can be found on the product page on our website. See the section under contact ratings. Of course, when switching high-currect devices the power source should be fused before the relay board. =)

[davejames]

...well, I'll be.

The spec sheet strongly implies that, under certain conditions, the relay can switch 12A. And it's not even a mercury-wetted type.

Impressive.

[erco]

RELAYS?

Kinda old school,huh?

I'm diggin' it! :)

[Ttailspin]

...The 2x3 header on the left provides ground and signal access to trigger each relay and can accept a standard servo cable such as those commonly used with many of our other accessories.

What happens if I plug this 2X3 header into the servo header on the Prop Proto board or the PPDB?.
What happens to the five volts? or V_ext if I have that hooked up?.


-Tommy

[Ken Gracey]

Chris, excellent work. I've got one of these kits in hand and hope to build it this weekend. For many years customers have asked us for a simple solution so they can turn a light bulb on or off from their microcontroller. Instead of giving them what they want, we gave them all kinds of complex, expensive and sometimes co-processor solutions.

Finally, Chris delivers a simple DIY solution. Thank you Chris! If I had time I'd be replacing the darned Tekmar control system in my home's boiler.

Ken Gracey

[Roy Eltham]

Nice little handy board.

[ajward]

RELAYS?

Kinda old school,huh?

I'm diggin' it! :)

Erco... now =this= is old school!

90169

I've always wanted one of these for some project.
(Yeah... probably watched too many old time monster movies.)

[PJ Allen]

I know that I've recommended similar kits/boards but such a thing was always just a bridge too far ("it costs too much", "I can't solder", "I need one, not two... I need two, not one... Those are spdt, I need spst..."

[Martin_H]

Amanda, hook a servo up to that knife switch and you'll have something.

[bill190]

I like mechanical relays for their ability to totally isolate electrical circuits.

For example all the wiring in a home or business for a security system can act as an antenna. Or a nearby lightning strike can induce a high voltage in that wiring. If you have a transistor on the end of that wiring, Zappp! But if you isolate the wiring from the transistor using a good old fashioned mechanical relay, it becomes a tough reliable system.

The most "cool" relay I have ever seen is a stepper relay...

90171

[Chris Savage]

What happens if I plug this 2X3 header into the servo header on the Prop Proto board or the PPDB?.
What happens to the five volts? or V_ext if I have that hooked up?.
-Tommy

Tommy,

Since the relays require 12V to power them and that comes from the terminal block, the center pin on the servo headers is not connected. This frees you to connect the board to a BoE, PDB, PPDB, or any board that has a servo header and connects the ground and signal. This is the same way our HB-25 works, not connecting the servo voltage pin, since it isn't needed by the host controller.

The 12V relays do work with a little less voltage (see the datasheet on our website), and in a demo here on my bench I have provided power from the BoE VIN to the terminal block on the Relay Board. I also connected two servo conection cables from the BoE servo headers to the headers on the relay board (see red arrows in picture). You might notice I didn't connected the ground wire for power in this case since it is common with the BoE and the servo cables are already connecting ground.

90172

The resistor chosen on the input of the driver transistors was chosen to provide enough base drive current from 3.3V or 5V systems based on the gain of the transistor and the current required to engage the relay. As Ken said, this is an easy solution to turn on a 120VAC lamp, motor, pump, etc. And of course you have two relays, so you can control two different devices while providing isolation. I hope this helps.

[Chris Savage]

I know that I've recommended similar kits/boards but such a thing was always just a bridge too far ("it costs too much", "I can't solder", "I need one, not two... I need two, not one... Those are spdt, I need spst..."

As a kit we'll keep the cost on this as low as we can.

[Ttailspin]

Since the relays require 12V to power them and that comes from the terminal block, the center pin on the servo headers is not connected. This frees you to connect the board to a BoE, PDB, PPDB, or any board that has a servo header and connects the ground and signal. This is the same way our HB-25 works, not connecting the servo voltage pin, since it isn't needed by the host controller.

I figured it was as simple as that, but I just wanted to be sure,
I almost had some trouble with the QTI sensor wiring harness. Good thing I double check my wiring...:)


-Tommy

[Chris Savage]

Tommy,

Everyone should always feel free to ask question on products, especially when, as in this situation, the only information is available right here in the thread about the coming product. We will sometimes use feedback given at this stage to make minor changes to a product, however in this case I have sent a few samples out for direct feedback because it is such a simple product. All questions and feedback are appreciated.

[Shawn Lowe]

Looks good! Gonna have to get me one or two!

[PJ Allen]

The picture in #13 puts it in perspective - it's a big ol' honker.

PV Jr. - I love mine, indispensable. Definitely get a base mount (a 308 or 312) for it.

[davejames]

The picture in #13 puts it in perspective - it's a big ol' honker.

Holy moly!!! I didn't read through the dimension info and missed the physical size.

Now I get why it's spec'ed for mulitple amps switching current...

[jlumens]

This might be a dumb question because I am really new to all this. Also, I have never posted to the forums before so forgive me if this question is inappropriate.
How will this compare to the EFX-TEK RC-4 Relay Control Board?

[Chris Savage]

Julia,

Your question is completely welcome and valid. The RC-4 uses Solid State Relays, whereas the Dual Relay Board Kit uses mechanical relays. Solid State Relays are great for switching AC loads especially when you want to minimize noise in the system. Some SSRs such as the Crydom relays used with the RC-4 have zero-crossing detectors to make this possible. However SSR relays are either AC or DC in their configuration and cannot switch both AC/DC circuits whereas a mechanical relay can. I'm not sure if there are SSRs for the RC-4 which can handle DC, but I doubt it. I believe the SSR current rating is also lower than the mechanical relays used on the Dual Relay Board Kit. If you have any additional questions, feel free to ask.

[xanadu]

Mechanical relays are irreplaceable. I have been scouting premade relay boards and this one looks great put me down for three.

[xanadu]

Could you tell me the mounting hole dimensions for the board?

[doggiedoc]

@Chris - very nice. Did I over look the release date or was it not mentioned? I'm going to need a few of those.

P

[jlumens]

9018490185I went to the EFX-TEK web site and downloaded cut sheets for both the AC and the DC relays that they recommend. The AC relays are rated at 240 VAC at 3A and the DC relays are rated at 60 VDC at 3A. If I can figure out how to attach the cut sheets to this response I will. I marked the specific model of each that is recommended.

[Chris Savage]

Could you tell me the mounting hole dimensions for the board?

The mounting hole centers are 1.5" x 2.0"

[Circuitsoft]

For people who want a smaller automotive-environment version, is there any chance of making a relay board with a Panasonic CT512 relay?

[Chris Savage]

@Chris - very nice. Did I over look the release date or was it not mentioned? I'm going to need a few of those.

P

Doc, very first post. Should be middle to end of this month. I think it mainly depends on how long to get the boards.

[john_s]

I hope there's some space left to consider rev.b with some smart interfacing as in Communication Module (http://www.youtube.com/watch?v=zOLoL7W5F_M&NR=1&feature=endscreen)

[Chris Savage]

PV Jr. - I love mine, indispensable. Definitely get a base mount (a 308 or 312) for it.

PJ,

I do have a base for it...sort of...I have the 335 Magnetic Base which I was going to use to attach it to my metal bench in the garage, but this unit is so handy for smaller, lighter work that I prefer to keep it inside, so I haven't even taken the 335 out of the packaging. And the PV Jr. hasn't yet needed a base for what I use it for.

90194

When I need something bigger I use the Model 315 PCB Holder (http://www.savagecircuits.com/forums/content.php?283-PanaVise®-Model-315-PCB-Holder), equipped with a custom base by Matt Gilliland (http://www.flickr.com/photos/savagecircuits/6242110919/).

And speaking of the PV Jr. Ken Gracey has assembled 18 soldering stations for the Parallax Expo (http://www.parallax.com/expo). Each station includes a PV Jr. I'll leave it to Ken to post the pictures of the kits since I do not have them. =)

UPDATE: Ken sent me the pictures of the PV Jr./Hakko Soldering Stations that will be set up for use at the Parallax Expo.
9021090211

[xanadu]

Thanks for that info, I have a project using relays that will be done around the same time so I hope to use yours.

Is there going to be an optocoupler board?

[John R.]

I was fortunate enough to be sent an evaluation kit on the Dual Relay Board Kit. The documentation was very clear on assembly instruction, and included a good description on the theory of operation, and how to calculate the resistor values for the transistor.

The board is very compact, and if the suggested order of assembly is not followed, it will be a challenge to place the smaller components.

I will be putting the relay board inside an outlet box, and using to control a heater and pump for an aquarium, or using it to turn on a shop vac, either via I/R or R/F control (and/or current draw of a sander).

Very nice kit!

[doggiedoc]

John - I too was fortunate enough to receive an evaluation sample of the kit. I will assemble it as soon as time allows, but I can see that the board is well made and and the components are top quality. I have several uses in mind - and will report back on my progress after assembly!

Paul

[tonyp12]

I'm more in to solid state.
Would there be a demand for this $9 (populated) board?
Dual 8Amp continues.

With a rather low Vds-max of 20V would be good for automotive mostly or other 12v systems.

Vgs is extremely low and mosfet will be fully on at 3v for direct Prop pin drive.
But don't need a MCU to work, you can use the pull up/down pads for phototransistor etc.

[bsnut]

Welcome to the forums Julia.

That's ok. The difference between EFX-TEK's RC-4 and the Parallax relay kit is, that the RC-4 is controlled by serial commands from the host controller and the relay kit isn't. Another difference with the RC-4 is, that it uses 4 Crydom Solidstate relays and the Parallax kit uses two mechanical relays that have Normally Open and Normally Close contacts to connect to and are controlled by High or Low (PBasic) commands from your controller.

BTW, the RC-4 used to be a product that was sold by Parallax about 6yrs ago and now is sold by EFX-TEK.

[Chris Savage]

We have not ruled out releasing a Dual SSR Relay Board, however the focus is currently on the mechanical unit as it serves an educational role and is generally more flexible in application.

[Loopy Byteloose]

After going back and forth, I have come to prefer the mechanical relays over solid-state. The primary advantage of solid-state is that they may offer direct connection from 3v or more - where as mechanical relays often require a boost to 12VDC in order to work.

That boost implies a more complex power supply for mechanical, but there are a lot of dual switcher power supplies available with +5 and +12. And many of the Propeller Boards with accept a +12VDC as raw power, then step it down as required.

There are great advantages in the mechanical relay in terms of adaptiblity. Both AC and DC can be used. And most relays are DPDT; whereas solid-state are often SPST.

Eventually, one has to become knowledgible of both - but the mechanical is a better item for the rank beginner as a first buy.

BTW, it used to be that the solid-state relays actually took up more space than the mechanical and often ran hotter - but they were silent. Currently, everything is changing - so it is hard to generalize. I still have several 'hockey puck' solid-state relay, but there is NO REASON that you much buy such big clunkers if space is short.

Furthermore, I generally run 12amp relays eventhough I might be using only 3 or 4 amps. That headroom just means that the relays last longer and less problems arrise.

[erco]

the focus is currently on the mechanical unit as it serves an educational role and is generally more flexible in application.

+1, my relay brother!

[Chris Savage]

Appeciated. If it weren't for the educational theme I would have used a FET and SMD components to switch the relay.

[tonyp12]

Relays with DPDT,high-side, A/C etc. a good thing.
But not being able to do PWM to dim a light etc., only a mosfet can do that.

[Chris Savage]

Relays with DPDT,high-side, A/C etc. a good thing.
But not being able to do PWM to dim a light etc., only a mosfet can do that.

A MOSFET will only work on a DC light. For AC you would need a TRIAC-based circuit with a delay and zero-crossing detection. Still, compared with simply turning high-power devices on/off, PWM control of such devices is less common.

[tonyp12]

Two MOSFETs with their source pins connected together as in the Phidgets SSR module with the NEC/CEL SSR IC will also drive AC loads
This works since all MOSFETs have a substrate diode that always conducts current in the reverse direction
And that is what I will do with the second version of my relay board.

[mojorizing]

Hello Chris,

Will the Dual Relay Board Kits be available for purchase soon?

Thanks,
Kevin

[Chris Savage]

They should be available some time in April.

[doggiedoc]

Chris -
Thanks for letting me evaluate a kit. I've just finished assembling the kit and it was a very strait forward process. The silkscreening on the board is very clear and I had no trouble with parts placement at all. Soldering skill is above beginner but I would think the most could handle it fine. Board quality is fantastic. Exactly what I've come to expect from Parallax.

I look forward to hooking it up and testing it now. More comments will follow.

Paul

[vanmunch]

Keeping my eye out for these to be on the new products page...

[Chris Savage]

We should have these on our website Monday or Tuesday.

[RS_Jim]

Chris,
Did they make it up to .com yet? I could not find it this am. Would like to pair this with a spinnernet to provide remote power control for a pair of wireless printers.
Jim

[Chris Savage]

Jim,

Had to retake the photos for the documentation. I am sending everything in today (again). I have the same camera (Nikon D80) but fail to take the same level of quality pictures, so yesterday while in the office I decided to get a crash course in D80 product photography. Once I send everthing in it should be up in a day or so. Sorry for failing to deliver on my original date. I took pictures with two different cameras and they were too dark and grainy.

[Leon]

I have a Nikon D80, as well. I'm ashamed of some of the photos I take with it, mainly because I can't be bothered to set up the tripod and get the lighting correct.

[Chris Savage]

Well I never got good photos from my Cell Phone camera. But it is a little embarassing when pictures from my Sony Hanycam HD Video Camera come out better than the Nikon D80, which cost three times as much. It seems I was not properly setting up several settings and of course, Auto Mode can't fix everything. Oh, and I have a Tripod, but I still have to use a remote because it is not real high quality, so pushing the button causes it to shake too long for the picture to come out. Maybe sharing this information will help others in this situation. I sought help from someone who did know what they were doing.

[Leon]

What I really need for photographing my electronic creations is a light tent (cheap) and a couple of suitable lamps (quite expensive). I have a home-made IR remote using a little PIC, but I usually use the self-timer if I have the camera on a tripod, to avoid camera shake. My tripod is a very good Manfrotto one, anyway.

[RobotWorkshop]

Trying to get the lighting just right can be a pain. If the item is small you can get great results by using something like this:

http://www.ebay.com/itm/Elmo-EV-400AF-Color-Video-Presenter-Document-Camera-/200749958487

You can often pickup used units pretty cheap. I don't use the built-in camera but have found that it is often worth using just for the controlled lighting. This model also can light from underneath as well.

[Chris Savage]

I definitely need something like that. I also saw a kind of product tent camera setup at ThinkGeek.com. Anyway, the new photos are done and I have sent the docs to our Tech Support Dept. for review. As soon as they approve them they go to our editor and we can then put them up on the web with the product. Trying for Friday on this. I will keep you updated. Thanks for the feedback everyone (and the patience)!

[RS_Jim]

Any word on when this will hit?

[Chris Savage]

Jim,

I was in Rocklin yesterday and talked to out Tech Support Dept. who still has the product in review. As soon as they're done we'll be about 2 days from selling them. I apologize for the delay.

[RS_Jim]

Thanks Chris.
Jim

[Chris Savage]

Okay, the kit has been through all the hoops and should be online for sale by this afternoon or tomorrow morning at the latest. Our WebDev team is getting things up as quickly as possible. As for the previous delays, we're working on improving our process to avoid hang-ups in the future.

[Vern]

Thanks! As soon as they hit I'll be ordering one.

[Chris Savage]

And...they're up! :thumb:

Get yours now...the Dual Relay Board Kit (http://www.parallax.com/tabid/768/ProductID/843/Default.aspx)for $19.99! Woot!