Operating 24Vdc 0.3A solenoid valves.

[fuzzybear]

Hi All,

New here and new to electronics so please excuse any stupid questions.

I am planning on implementing an opensprinkler to replace a very old sprinkler system in my greenhouses. The current system operates 20 zones with solenoid operated diaphragm valves. These 20 valves are 24Vdc 0.3 Amp.
My question is basically if I use a supply voltage of 24Vdc 0.3Amp to the opensprinkler circuitry will it suffice to replace the triacs with MPSA14 transistors or do I need something more or different?

As I am quite new to this I am looking for the simplist option.

Bren

[Ray]

The current system operates 20 zones with solenoid operated diaphragm valves. These 20 valves are 24Vdc 0.3 Amp.

do you know the model number / link to the valve? The first thing is to make sure these are indeed DC valves. Also, whether it’s latching or non-latching. If you can tell me more about the specifications of the valves, I can give you better advice.

[fuzzybear]

@ray wrote:

The current system operates 20 zones with solenoid operated diaphragm valves. These 20 valves are 24Vdc 0.3 Amp.

do you know the model number / link to the valve? The first thing is to make sure these are indeed DC valves. Also, whether it’s latching or non-latching. If you can tell me more about the specifications of the valves, I can give you better advice.

This is a link to the solenoid. http://www.brinkman.com/component/virtuemart/onderd/onderd-kranen/onderd-kranen-bluera/brain-solenoid-24v-dc-coil-ring-detail?Itemid=0

I have found a bit more detail in this pdf http://www.tasseron.nl/sites/default/files/product_groups/downloads/BR.pdf but unfortunately it is Dutch. I will continue to search to see if I can find some more information.

Here is a link with general information for the valve http://www.brinkman.com/catalogue/onderd/onderd-kranen/onderd-kranen-bluera

Bren

[fuzzybear]

Hi I have tried searching for more information. But above is all I can find for these valves. They are more then twenty years old. The solenoid is definitely 24vdc 0.3 Amp and is a plunger type solenoid that uses a spring return. I can make some tests directly on the solenoid if this would help. This type of solenoid is sold as a dc or ac variant but costs approx 30 Euros each which would be quite an investment for 20 zones. There are also two types of diaphragm valves that I know of using these solenoids. That is the Elmeco and the Rain Bird 11/2″ valves.

Please let me know if there are any checks I can make to clarify any necessary details.

Bren

[Ray]

OK, interesting, I think this is the first time I see 24V DC non-latching valves. The user manual seems to refer to both 24V DC and 24V AC coil voltage, I assume this means two different types of solenoid?

Anyways, if you’ve already invested in the DC valves, you can modify the OpenSprinkler circuit by replacing the triacs with transistors like MPSA14. You won’t need the flyback diode any more because all current versions of OpenSprinkler have per-channel transient voltage suppressor (TVS) or MOV (these serve as surge voltage protectors). You can also use a relay board in conjunction with OpenSprinkler, but it will be much more bulky.

[fuzzybear]

@ray wrote:

OK, interesting, I think this is the first time I see 24V DC non-latching valves. The user manual seems to refer to both 24V DC and 24V AC coil voltage, I assume this means two different types of solenoid?

Yes you can purchase an ac or dc version of the valve or just exchange the solenoid to change the type. Unfortunately I did not purchase these valves or sprinkler system they came with the property. The old controller is completely dead and more then 30 years old.

@ray wrote:

Anyways, if you’ve already invested in the DC valves, you can modify the OpenSprinkler circuit by replacing the triacs with transistors like MPSA14. You won’t need the flyback diode any more because all current versions of OpenSprinkler have per-channel transient voltage suppressor (TVS) or MOV (these serve as surge voltage protectors). You can also use a relay board in conjunction with OpenSprinkler, but it will be much more bulky.

I was also taking a look at your blog about the relay board but if I understand correctly I would still have to replace the Triacs anyway, Is this correct?

It is also a little unclear for me how the relay board works as there seems to be more outputs then inputs. The old controller also has some kind of relay board with 8 inputs that control 20 outputs(zones).
Is it not necessary to reprogram the opensprinkler for this case?

Thanks for your help

Bren

[Ray]

I was also taking a look at your blog about the relay board but if I understand correctly I would still have to replace the Triacs anyway, Is this correct?

Not necessarily. If the relay board is of ‘active high’ type, you just need to solder a wire from the gate of the triac (basically the shift register output) of each channel to the relay’s data pin. The blog post shows replacing triacs by transistors because the relay board I was using is of ‘active low’ type. So the transistors serve as inverters to reverse the logic.

It is also a little unclear for me how the relay board works as there seems to be more outputs then inputs.

Typically each relay channel has three pins on the input side: VCC (e.g. 5V), GND, and data pin (connected to microcontroller, or in this case, a shift register output pin); and three pins on the output side: NO (normally open), CO (change over), NC (normally closed). At resting position, CO and NC are connected; when relay is activated, CO and NO are connected. To put everything together: first, one wire from each solenoid should come together and go to the COM (common) terminal; then, the other wire of each solenoid can go into the relay NO pin. Finally, the CO pin of each relay is connected to GND. This way, when the relay is activated, it completes the circuit from 24V AC common wire -> solenoid -> ground (which is tired to the other wire of 24V AC). Hope this makes sense.

[fuzzybear]

Ray,

Thanks for the reply, with this explanation this is now clear for me. I think I will go for the option of replacing the triacs as this seems to be the simplest option. I have found a supplier where I can buy the MPSA13, as the 14 does not seem to be stocked so much here in the Netherlands. I did find one supplier but he only supplies to registered company’s or professionals as with a lot of the electronic suppliers in the Netherlands these days.

Bren

[Ray]

Sure, sounds good. MPSA13 and A14 are interchangeable, so either should be fine.

[Author]

Posts