Author Topic: Opensprinkler boards Round 2 Q & A  (Read 11110 times)

Offline tangmonster

Re: Opensprinkler boards Round 2 Q & A
« Reply #120 on: July 26, 2018, 11:10:09 AM »
Please remember that the raspberry pi board is powered from the AC with a switch mode supply that regulates the 5.1V for the raspberry pi.

Do NOT power the raspberry pi with 5V also. only 24V ac is needed.

Even a pi 3 under normal use with wifi should stay under 1 amps 99% of the time.

Remember the 25VA transformer can roughly supply 1 amps at 24Vac.

This gets regulated to 5V with an onboard switch mode regulator.

So you can get much more than 1 amp of the 5V.

Switch mode regulators are not as inefficient as linear regulator.

So if you are drawing 5V and 1 amps ( 5W) from the output of the regulator , and the regulator is roughly 80% efficient you will be drawing little bit over 200mA from the 24Vac transformer for the pi. Leaving further 800ma headroom for your solenoids and relays etc.

But a pi in idle like we are using it with wifi enabled really should average around 300-500mA  (thumbsuck)


Here is some text on current draw:

https://raspi.tv/2016/how-much-power-does-raspberry-pi3b-use-how-fast-is-it-compared-to-pi2b


Offline RVZ

Re: Opensprinkler boards Round 2 Q & A
« Reply #121 on: November 26, 2018, 11:40:18 AM »
I pm'd Tangmonster to get some info, but maybe someone else can also assist. 

I bought one of the OpenIrrigation boards from Smartkit last week.  Apparantly you can control a water pump through this as well?  Anyone know what I will need to do this?

I bought this for the transformer:  https://www.acdc.co.za/pages/product-individual?25VAP-24-T

I have one of these water pumps:  https://www.brights.co.za/product/dab-jet-102-wellpoint-pump/

Xrapidx on MYBB did this with a relay, but I'm not quite sure about the details of what I need, and don't want to blow up the board / pump / Pi...  ;-)

Offline mygoggie

Re: Opensprinkler boards Round 2 Q & A
« Reply #122 on: November 26, 2018, 03:21:29 PM »
You will need a non-latching relay to start the pump. The relay to be switched by one of the output channels.

Your pump will draw in the order of 1kW at 220VAC which is approx 5A. Make that 10A that the relay will have to handle for safety and durability.

The coil of the relay will have to handle 24VAC as this is the voltage of your output channel.

I would use one such as this https://za.rs-online.com/web/p/non-latching-relays/0353843/ that plugs into a base such as this https://za.rs-online.com/web/p/relay-sockets/0353944/ mounted on a standard piece of DIN rail.

Read howto - https://rayshobby.net/wordpress/using-24v-ac-relays-with-opensprinkler/
Herman

~ To heal the soul is to embark on a new journey. ~

Offline RVZ

Re: Opensprinkler boards Round 2 Q & A
« Reply #123 on: November 26, 2018, 03:28:09 PM »
Thanks for the info, especially the howto, I'm still a bit unsure of how it will all connect.  It will probably make more sense once I get the parts and start putting it all together.

Tangmonster suggested these, which I ordered today.

relay: http://www.mantech.co.za/ProductInfo.aspx?Item=14M2219
socket: http://www.mantech.co.za/productinfo.aspx?item=14MA203


Offline mygoggie

Re: Opensprinkler boards Round 2 Q & A
« Reply #124 on: November 27, 2018, 10:18:09 AM »
The wiring itself is a simple exercise if you know what to do. You will need a 2 pole 10A circuit breaker to protect the relay and cable to the pump as well. This will clip into the same DIN rail as the relay base.

Use something like this - https://za.rs-online.com/web/p/mcbs/8473125/

You may argue you do not need to isolate the Neutral line to the pump, but I prefer doing that as you might want to work on the pump and a local complete isolation is much more secure IMHO.

The wiring diagram is fairly simple. I will see if I can rustle something up.
Herman

~ To heal the soul is to embark on a new journey. ~

Offline RVZ

Re: Opensprinkler boards Round 2 Q & A
« Reply #125 on: November 29, 2018, 01:54:07 PM »
The wiring diagram is fairly simple. I will see if I can rustle something up.

Thank you, will really appreciate it.  :)

Offline mygoggie

Re: Opensprinkler boards Round 2 Q & A
« Reply #126 on: December 01, 2018, 09:25:55 AM »
Thank you, will really appreciate it.  :)

Here you go. All equipment to be mounted in a IP65 rated enclosure. The isolator, two circuit breakers and the relay to be mounted on a DIN rail. Supply cable to be 2,5mm2, connecting wires to be 2,5mm2.


« Last Edit: December 01, 2018, 09:30:57 AM by mygoggie »
Herman

~ To heal the soul is to embark on a new journey. ~

Offline rodga

Re: Opensprinkler boards Round 2 Q & A
« Reply #127 on: December 04, 2018, 10:05:22 AM »
So I think this load shedding must have got the better of my opensprinkler setup.
I cant seem to detect the opensprinkler when opening the app and then the pi itself is also not connected when looking at the device list.

When powering on the pi green led will flash twice, then once more and nothing after that.
Can anyone confirm what the green led on the pi is supposed to do? Is on, off or flashing in normal operation?
Hopefully im lucky and only my sdcard has gone or something?

Offline mygoggie

Re: Opensprinkler boards Round 2 Q & A
« Reply #128 on: December 04, 2018, 11:19:43 AM »
Two greens flashing means it is alive and will look at the SD card. Third flash AFAIK means it is reading the SD Card.

So your SD card is shot is my first instinct. Of course you have made a DD image of the SD card and stored this offline so that you can simply rewrite a new SD card ...  :whistler:
Herman

~ To heal the soul is to embark on a new journey. ~

Offline rodga

Re: Opensprinkler boards Round 2 Q & A
« Reply #129 on: December 04, 2018, 12:04:04 PM »
Two greens flashing means it is alive and will look at the SD card. Third flash AFAIK means it is reading the SD Card.

So your SD card is shot is my first instinct. Of course you have made a DD image of the SD card and stored this offline so that you can simply rewrite a new SD card ...  :whistler:
yeah ofcourse I have  :whistler:
Will check it out this evening when I get home