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).
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!
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.
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.
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.
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.
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.
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.
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.
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
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.
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.
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.
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.
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.
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)!
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.
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.
Hi! I've just bought one of this kits from RS Components and have been very impressed with it... However, I need to modify it so that it's switched by grounding an input, rather than adding 3.3 -> 5V onto a pin, as that's the only signal that the kit I've got which will be triggering it can give...
I've modified the circuit diagram (in paint, please forgive me!) to use a PNP transistor instead of an NPN (a pair of 2N3906) and reversed the + and - inputs and the polarity of both the LEDs and the Diodes... (attached to this post)
I know that this will also make pins 5 and 6 (and the mounting points!) be 12V instead of ground, but as long as I don't mind that (it'll be mounted in a box, suspended on plastic mounts) and as long as I connect the return from my switching device straight back to the ground of the power supply, I think I should be OK...
In your opinion, will this work, or am I missing something? (it's been a long while since I did any electronics!)
Anyway, this is a brilliant kit that I just keep coming up with uses for since I bought one...
Comments
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!
Paul
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.
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.
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.
+1, my relay brother!
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.
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.
Will the Dual Relay Board Kits be available for purchase soon?
Thanks,
Kevin
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
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
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.
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.
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.
Jim
Get yours now...the Dual Relay Board Kit for $19.99! Woot!
I've modified the circuit diagram (in paint, please forgive me!) to use a PNP transistor instead of an NPN (a pair of 2N3906) and reversed the + and - inputs and the polarity of both the LEDs and the Diodes... (attached to this post)
I know that this will also make pins 5 and 6 (and the mounting points!) be 12V instead of ground, but as long as I don't mind that (it'll be mounted in a box, suspended on plastic mounts) and as long as I connect the return from my switching device straight back to the ground of the power supply, I think I should be OK...
In your opinion, will this work, or am I missing something? (it's been a long while since I did any electronics!)
Anyway, this is a brilliant kit that I just keep coming up with uses for since I bought one...