Switching 24AVC solenoid

Hemi345

Senior Member
I'm currently using a Crydom LC241 SSR to switch a 24VAC water solenoid (2.3W). It's been running great for a few years now, but I'm redesigning the project to add a lot more functionality and in the process, I need to use 3.3V for all components. The LC241 datasheet doesn't specify Vf of the led, but indicates control voltage is 4-10VDC. Since it's buried in the project and not easily tested it at 3.3V, I'm looking for something else especially considering its EoL anyway.

I can't find any other specs on the solenoid like surge and run current, just 2.3 watts. Would any of the following SSRs be appropriate in this application?

AQY211EH (30V, 1A) or AQY212EH (60V, 550mA)

G3VM-41AY1 (40V, 2A) or G3VM-61AY1 (60V, 500mA)

Thanks!
 

premelec

Senior Member
Not an answer - but a question - where does your 3.3v come from? Having a somewhat higher voltage would help a lot - could be unregulated...
 

Hemi345

Senior Member
Powered will be provided by a 5-9V AC/DC adapter then regulated down to 3.3V with a NCP1117DT33G. I'm limited to the PCB space because of the enclosure it's in, so something DIP-4 or SIP-4 size or smaller would be ideal... I could use the LC241 (there's just enough room) if I use a transistor to switch the LED, but I'd like to keep the component count down to a single IC with Rc, if possible.
 

premelec

Senior Member
@Hemi345 I wonder if you ever tried driving your 24VAC solenoids with lower DC voltage [instead of the 24VAC]. Many AC solenoids could work on DC - with appropriate shunt diode etc... depends some on how fast you want them to work. [and if you enjoy AC buzz... ;-) ]

I did a fast search on this subject: http://ecmweb.com/cee-news-archive/using-ac-coils-dc-power-1 seemed ok and there were lots of other hits...
 
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rq3

Senior Member
@Hemi345 I wonder if you ever tried driving your 24VAC solenoids with lower DC voltage [instead of the 24VAC]. Many AC solenoids could work on DC - with appropriate shunt diode etc... depends some on how fast you want them to work. [and if you enjoy AC buzz... ;-) ]

I did a fast search on this subject: http://ecmweb.com/cee-news-archive/using-ac-coils-dc-power-1 seemed ok and there were lots of other hits...
That article is so wrong in so many ways I don't know where to begin. Please, no one go there!!!
 

lbenson

Senior Member
Just wondering why you picked that part over the G3VM-41AY1 I was looking at. Being cheaper is attractive but is there something else?

VO14642AT: 60V, 0.18Ω @ 1A w/10mA LED drive $2.66
G3VM-41AY1: 40V, 0.09Ω @ 2A w/ 5mA LED drive $5.37
I was looking on page 2 of the datasheet you linked to at IF (LED forward current) of 30mA, but I see on page 3 it says 10mA if I'm reading it correctly.
 

premelec

Senior Member
@rq3 I have used AC relays and solenoids on DC at various times - not by preference so much as available parts - what is your experience with that ?
 

Hemi345

Senior Member
I was looking on page 2 of the datasheet you linked to at IF (LED forward current) of 30mA, but I see on page 3 it says 10mA if I'm reading it correctly.
Ahh okay. Yeah, the test If is different on the Vf than on the Ron so I just went by the Ron test value. I'll order a couple of the Vishay model you found as it's cheaper. Thanks.

@premelec, I haven't tried running the solenoid on DC, but I have AC already available so I'll stick with that. I have a different project that I'm starting to work on that uses sprinkler valves I may experiment with DC on. I've read they can be run on 9-12VDC for short periods of time.
 

premelec

Senior Member
@Hemi345 - main thing AC / DC is ampere turns - i.e. same coil _current_ since DC mainly determined by resistance of winding and AC by impedance of winding [inductance & resistance] your DC voltage level will be well below the AC voltage level... or your coil will overheat - perhaps that's what concerns rq3. Have fun!
 

nekomatic

Member
I can't find any other specs on the solenoid like surge and run current, just 2.3 watts. Would any of the following SSRs be appropriate in this application?

AQY211EH (30V, 1A) or AQY212EH (60V, 550mA)

G3VM-41AY1 (40V, 2A) or G3VM-61AY1 (60V, 500mA)

Thanks!
The peak voltage of 24 V AC is about 34 V, so you can't use the 30 V part. Apart from that I don't see why the others shouldn't work, as long as you can drive the LED with at least the 'minimum' forward current specified.

You probably want some sort of transient protection across the SSR - are you using anything at the moment?
 

nekomatic

Member
I honestly don't know which of those two is most suitable - unless someone else here can help I'd probably ask that somewhere like electronics.stackexchange.com. Unless I've misunderstood the datasheet it looks as if the first one behaves like a zener though, so you'd need two opposed in series, whereas the MOV is non-polarised?
 
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