Geekzone: technology news, blogs, forums
Guest
Welcome Guest.
You haven't logged in yet. If you don't have an account you can register now.




429 posts

Ultimate Geek
+1 received by user: 37


Topic # 147084 8-Jun-2014 17:38
Send private message

looks interesting

http://www.ebay.com/itm/281205997347

View this topic in a long page with up to 500 replies per page Create new topic
 1 | 2
2284 posts

Uber Geek
+1 received by user: 651

Trusted
Subscriber

  Reply # 1061393 8-Jun-2014 18:24
Send private message

I bought a Raspberry Pi with the PiFace board to do something similar but with fewer I/O ports (more can be added).

The relays on this are rated at 250v as are the ones on the PiFace board.  The PiFace PCB itself however is not rated at 250v and I think the documentation says stick to 12v (from memory).  There is no indication that this equipment is rated for 250v.

^^^  CAUTION ^^^




"4 wheels move the body.  2 wheels move the soul."

“Don't believe anything you read on the net. Except this. Well, including this, I suppose.” Douglas Adams



429 posts

Ultimate Geek
+1 received by user: 37


  Reply # 1061398 8-Jun-2014 18:36
Send private message

the relay board on the oeezee says its rated at 250V. looks ike the control board is 5v. you can buy the relay boards seperatly for $19 USD for an 8 way board. the ralys are only 10A so youd have to watch what you switched with them otherwise use contactors for the heavier loads.

 
 
 
 


3267 posts

Uber Geek
+1 received by user: 77

Trusted

  Reply # 1061578 9-Jun-2014 00:35
Send private message

Unless all the low voltage circuitry is isolated inside the enclosure with no external connections, you cannot safely use these relays for mains.  For the form-C contacts the common pin is between the coil pins with about 5-6mm clearance, not the 3cm required for appliances.

The relay is rated only 3A for inductive loads, specs printed on it is for resistive loads: http://www.sanyourelay.ca/public/products/product_list_new.php?series=43&listby=0

Note that (other) relays that can handle large inductive loads are not suitable for switching signals (or LEDs etc.), because they need a high current in order to keep the contacts clean - it is a requirement of the contact plating.




You can never have enough Volvos!


2089 posts

Uber Geek
+1 received by user: 1000


  Reply # 1061601 9-Jun-2014 06:50
Send private message

Pity they didn't build it with SSRs instead of mechanical relays



429 posts

Ultimate Geek
+1 received by user: 37


  Reply # 1061978 9-Jun-2014 17:24
Send private message

SSRs have thier issues too. i prefer relays for this sort of thing.

The 3cm rule is stupid because every relay out there has less than 3cm clearance internally, (and  anything it mounts to.) also as its not an appliance but mounted in a sub board type enclosure the rules may be different anyway, just like wire sizing inside a SW board..
another option is to desolder the relay and break it out to an LY2N type relay for instance.

3267 posts

Uber Geek
+1 received by user: 77

Trusted

  Reply # 1062290 10-Jun-2014 06:20
Send private message

The 3cm clearance rule is for surface contamination.  A physical barrier or a sealed enclosure is also good.  On a PCB if you have slots routed in the board then the path is measured around the slot, not through the air.  Or a double insulated product also works.  It is about preventing high voltage breakdown to the user.




You can never have enough Volvos!


1572 posts

Uber Geek
+1 received by user: 175

Subscriber

  Reply # 1062341 10-Jun-2014 08:22
Send private message

I have just been playing around with an Arduino + 4xrelay board (looks very similar to these relay boards). With an ethernet shield and using MQTT I have a very reliable way of switching the relays, and monitoring digital input pins. Plan to put one inside my alarm panel to give me IP monitoring of alarm state and triggers (panel only has a dialler, no IP module). Also going to hack a spare RF dongle and use the relays to allow me to arm/disarm via my home automation system. Will also allow me to open/close the garage door.

That is all low voltage so no issues switching, and I can even power the Arduino from the alarm 12V supply. 

Not bad for a $US8 Arduino + $US8 ethernet shield + $US5 relay board!


20373 posts

Uber Geek
+1 received by user: 3880

Trusted
Subscriber

  Reply # 1062774 10-Jun-2014 17:39
Send private message

Ive had nothing but issues with ethernet shields stopping arping and dropping off the lan.




Richard rich.ms

3267 posts

Uber Geek
+1 received by user: 77

Trusted

  Reply # 1062821 10-Jun-2014 19:39
Send private message

richms: Ive had nothing but issues with ethernet shields stopping arping and dropping off the lan.

I am not surprised after looking at EMC/EMI issues from Beagle Bone which claims to meet compliance, but then discovering it was done by overdamping the DDR bus out of spec, and running the memory interface at it's slowest which is not what the released firmware does.  "Experimental" boards do not have to meet any form of compliance as long as they have a disclaimer that it is for lab use only, despite selling thousands/millions.




You can never have enough Volvos!


1572 posts

Uber Geek
+1 received by user: 175

Subscriber

  Reply # 1063255 11-Jun-2014 11:03
Send private message

Richms - how often does this happen for you? I have just setup an Arduino + Ethernet shield in a test config running an MQTT client. I will be notified if the device loses connection with the MQTT broker so will leave this running for a few days and see how it fares.

20373 posts

Uber Geek
+1 received by user: 3880

Trusted
Subscriber

  Reply # 1063256 11-Jun-2014 11:06
Send private message

20-30 mins with 4 phones hitting it regularly. Few days with a single pc hitting it.





Richard rich.ms

1572 posts

Uber Geek
+1 received by user: 175

Subscriber

  Reply # 1063264 11-Jun-2014 11:18
Send private message

What are you using these for?

20373 posts

Uber Geek
+1 received by user: 3880

Trusted
Subscriber

  Reply # 1063342 11-Jun-2014 13:14
Send private message

Just serving a page with a temperature from a couple of 1 wire sensors in aquariums.




Richard rich.ms

3267 posts

Uber Geek
+1 received by user: 77

Trusted

  Reply # 1063685 11-Jun-2014 22:04
Send private message

Try a different power supply, it might be too noisy.  Or run the power supply close to rated load, EMC compliance is done only at no-load and at full load so manufacturers don;t care what comes out of them at part load.




You can never have enough Volvos!




429 posts

Ultimate Geek
+1 received by user: 37


  Reply # 1064355 12-Jun-2014 19:43
Send private message

running power supplies at very low load is flakey. you get all sorts of harmonics int the supply that seems to get dampened at closer to spec loads.

 1 | 2
View this topic in a long page with up to 500 replies per page Create new topic



Twitter »

Follow us to receive Twitter updates when new discussions are posted in our forums:



Follow us to receive Twitter updates when news items and blogs are posted in our frontpage:



Follow us to receive Twitter updates when tech item prices are listed in our price comparison site:





News »

Phone prices rising as users move upmarket
Posted 24-Nov-2017 17:16


Talking net neutrality on RNZ Nine-to-Noon
Posted 24-Nov-2017 12:11


Air New Zealand experiments with blockchain technology
Posted 23-Nov-2017 15:39


Symantec selects Amazon Web Services to deliver cloud security
Posted 23-Nov-2017 10:40


New Zealand Ministry of Education chooses Unisys for cloud-based education resourcing management system
Posted 22-Nov-2017 22:00


Business analytics software powers profits for NZ wine producers
Posted 22-Nov-2017 21:52


Pyrios strikes up alliance with Microsoft integrator UC Logiq
Posted 22-Nov-2017 21:51


The New Zealand IT services ecosystem - it's all digital down here
Posted 22-Nov-2017 21:49


Volvo to supply tens of thousands of autonomous drive compatible cars to Uber
Posted 22-Nov-2017 21:46


From small to medium and beyond: Navigating the ERP battlefield
Posted 21-Nov-2017 21:12


Business owners: ERP software selection starts (and finishes) with you
Posted 21-Nov-2017 21:11


Why I'm not an early adopter
Posted 21-Nov-2017 10:39


Netatmo launches smart home products in New Zealand
Posted 20-Nov-2017 20:06


Huawei Mate 10: Punchy, long battery life, artificial intelligence
Posted 20-Nov-2017 16:30


Propel launch Disney Star Wars Laser Battle Drones
Posted 19-Nov-2017 21:26



Geekzone Live »

Try automatic live updates from Geekzone directly in your browser, without refreshing the page, with Geekzone Live now.



Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly to your computer or smartphone by using a feed reader.

Alternatively, you can receive a daily email with Geekzone updates.