solenoid problem

[ritayshida]

I have a naïve question about solenoid, but please someone help me out.

I have a valve 24V DC solenoid. I send a pulse through digital output (5V) to trigger a solenoid, however, solenoid doesn't fire (the valve doesn't open). The voltage I measured was 0.612 V (pulse ON) and 0.0082 V (Pulse OFF). Is this too low?

This is a second solenoid supposedly new. I used the same pulse trigger (voltage I measured was the same) to the first solenoid (24 V DC) and it worked fine. After having used the first one for three years, it had started leaking water even when I didn’t send any pulse to the solenoid. I thought the solenoid was no more usable so that I replaced it to the second one and now it’s not working, either…I do need help.


Thank you in advance,


Rita

 

[stevez]

Many solenoids operate when something close to their rated voltage is applied. They will operate at something slightly less but expecting a 24 vdc solenoid to open with 0.6 volts is expecting too much.

Unless this is some special kind of solenoid valve the valve will only operate in the energized state when 24 vdc (plus or minus some amount, see mfr's specs) is applied.

It sounds like you are trying to drive the solenoid with something that just doesn't have the power to drive it.

 

[panic mode]

stevez is absolutelly correct... you will need 24VDC to drive 24VDC load.

 

[ritayshida]

Thank you so much for your quick replies.

I understood why the current solenoid doesn't work (less voltage to triger 24V DC solenoid). But why did the first solenoid which is also 24V DC solenoid work in the same voltage settings then? It had been perfectly fine for three years.

Another naive qustion is:
Then what could be the best way to get enough voltage in my case? I want to send a trigger pulse though digital I/O.


I would really appreciate your reply. Thank you again!


Rita

 

[panic mode]

ok, i don't think the first one was same voltage. relays sometimes come in same housing and with almost identical part numbers since they belong to same family but have different specs... or...the power supply and/or output driving this relay are toast. did you check the voltages before, while original relay was still working?

 

[hjl4]

I have a valve 24V DC solenoid. I send a pulse through digital output (5V) to trigger a solenoid, however, solenoid doesn't fire (the valve doesn't open). The voltage I measured was 0.612 V (pulse ON) and 0.0082 V (Pulse OFF). Is this too low?

Definitely too low.

You can increase power delivered to solenoid by using a transistor. NPN.(or PNP)
Input the pulse on the base of transistorNPN, and the emiter to the 24V rail, and the colector to solenoid.
Of course have a diode across the solenoid to prevent back EMF damage, or lose transistor.A resistor may be necessary in series to solenoid also.

Just an idea.
Of course, maybe you should first confirm what panicmode is saying

 

[Roff]

Input the pulse on the base of transistorNPN, and the emiter to the 24V rail, and the colector to solenoid.

Hjl4, you really need to post a correction here. This is a recipe for smoke.

 

[ritayshida]

Many many thank to you all!!

The first solenoid I used is “Parker Hannifin Corporation, PIN 003-0111-900” and the second one is “PATENTED, PIN 360 P012-42”. The first one was already in the reward systems built by Crist Instrument Company, Inc (see their website: **broken link removed** ) Mine is Cat# 5-RLD-ES.

did you check the voltages before, while original relay was still working?

No, I didn’t check the voltage first one . I tried to find out the specs for both solenoids, and only found the website just saying “The dispenser unit is gravity fed through a low voltage, quick acting solenoid”, but didn’t say how much. So the possibility would be the old system has something, like Ron H says, to increase power between I/O and solenoid, or this specific solenoid is sensitive enough to be driven by 0.6V?

Rita

 

[ritayshida]

I called them and figured that this first one (see above website) does have IC between solenoid and I/O to increase power to 24V to trigger the second solenoid, which itself is trigged by 24V.

Then, the ways to use the second normal valve 24V DC solenoid triggered by TTL pulse would be
1. to create a relay to increase power between solenoid and DIO as the first one was
or
2. to use 24V DC power supply separately (but how?)

Please bare with me…

Rita

 

[hjl4]

Hjl4, you really need to post a correction here. This is a recipe for smoke.

Yes you are right RonH.

Sorry about that, I was busy and tried to squeeze in a reply.
Definitely NO GOOD.

I was thinking Darlington such as Tip 120 ect....

Input of signal on base is OK,if it is from low power,such as microcontroller, Then emiter to negative side or ground, of 24V supply,
and collector to solenoid (or coil).

Hope this clears it up a bit.

BTW, I really should put a schematic up there.
Anybody know where to get all those symbols that people use to do schematic on MS paint? If I had that, I would show you what I mean.

 

[audioguru]

Hi HJ,
I also use MS Paint for schematics and I just copy and paste transistors, resistors and things from other schematics. Sometimes I use the "Prt Scrn" key with a PDF then paste it into MS Paint.

 

[hjl4]

Great idea audio.

I'll try that.

It just seems to simplify things for me, as I've tried and disliked most Ecad software(Eagle for example).

I only use them to make PCboards and final schematics.

MS Paint would be much faster I think, as you don't have to be searching for specific components.

You just need symbols and traces to explain most circuits.

Thanks for the tip.

 

[hjl4]

Ok Audioguru, This is my first schematic with MS Paint, so don't laugh.

This demonstrates what I was trying to explain to you ritayshida, in a schematic.

 

[audioguru]

Hi HJ,
Nice schematic. Did you know that lines are straight when you hold down the shift Key?
Did you know that JPG files like yours show schematics with fuzz, but saved with GIF or PNG file type are perfect?
JPG is a lossy compression technique for photographs.
GIF and PNG also compress, but without loss for schematics. :lol:

 

[hjl4]

Thanks for the tips Audio, I'll have to remember that.

Getting back to the question ritayshida was asking.

Then, the ways to use the second normal valve 24V DC solenoid triggered by TTL pulse would be
1. to create a relay to increase power between solenoid and DIO as the first one was
or
2. to use 24V DC power supply separately (but how?)

1. The schematic I posted does just that.

2. if the old solenoid used an IC to amplify the DIO signals, then again the schematic I posted does the same thing.The Darlington transistor TIP 120, is very responsive to low power input signals, and can handle 5amps? at 12V. I can't remember exactly, but you can look that up to make sure.

All you would have to do, is calculate the resistor value for the input signal, and also check to see if you would need one in series for the solenoid.

Good Luck!

 

[ritayshida]

Thanks A LOT!! Especially hjl4, I appreciate that you put the effort for me to draw the schematic which really help my understanding. I want to try the circuit you described. I am literally Electronic Newbie so that I drew your schematic by myself just to make me understand what is drawn on that. Is mine right?

PS. I used the PowerPoint since I know they can draw connectors and also found the website (http://www.kpsec.freeuk.com/symbol.htm) which we can download the circuit symbols as gif format and so on.

 

[hjl4]

Your schematic looks fine to me.

Glad I could help you ritayshida!

Good Luck with your project..