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Push Button H2O - Reversing Polarity

mcasey

Jul 9, 2016
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"Yes, I am going by what the link you posted said. Did you try to see if using the same polarity twice also might flip it? Because that is what I read the specs as saying."

Have you tried this as requested by Bob?

Confirm state of valve, ie open or closed.
Connect the black wire to negative.
Briefly touch red wire to positive and then disconnect.
Reconfirm state of valve.

Did the valve change state?


no. i have to touch red to positive and black to negative to open the valve, then i have to touch the red to negative and black to positive to close it. I only have to touch it momentarily because it is a latching valve. Using the same polarity twice does not change the state of the valve.
 

mcasey

Jul 9, 2016
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Don't know what you mean "polarity issue".
Do you have a tx/rx?
Don't know why you need 2 channels but most come with 4 or 5 for about $30 anyhow.
Do you have a receiver controlled switch also or were you referring to the radio when you say you have one.

i have a tx/rx. i tried using it to supply power to the valve remotely, but i can only send the valve into one state. i would need to reverse the polarity to change the state.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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This switch works great. However, what if I wanted to activate the switch wireless? Could I use some sort of relay to achieve the same results?

You could use an H bridge to enable power to be applied in either direction. Presumably the receiver will only apply a momentary pulse.
 

Kiwi

Jan 28, 2013
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Like Bob, I would be rather annoyed if I had purchased that solenoid valve and found that it only works by changing polarity.
That is not how the description reads to me.
I would also not have expected a polarity reversing valve to have a red and black wires.

Another thought.
The valve is rated at 6v.
Is your 9V battery capable of supplying sufficient current at 6V to operate the valve correctly?
It may be that by reversing the polarity from your 9V battery the valve will change state.
I would suggest that you try it on a 6V power source that is able to supply a few amps without the voltage dropping, eg SLA battery.
 

mcasey

Jul 9, 2016
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You could use an H bridge to enable power to be applied in either direction. Presumably the receiver will only apply a momentary pulse.

I've been researching H bridge. The only circuits i find still require two switches. How would i wire in the receiver? Would I need two channels, both momentary, in order to activate either side of the bridge?
 

Kiwi

Jan 28, 2013
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Looks like Bob and I have been led astray by the ambiguous information given by the supplier of your valve.
As you have discovered, your valve probably works by changing polarity.
The wire colours indicate which way to connect power to get a particular operation.

Just found this on another manufacturer's website;
  • Valve opens with quick positive pulse (red wire to "+" & black wire to "-")
  • Valve closes with quick reverse pulse (red wire to "-" & black wire to "+")
  • Valve stays in position with no additional power being applied
Not sure how you can easily get remote operation with a single input.
Possibly you could try a magnetically latching changeover relay?
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Would I need two channels, both momentary, in order to activate either side of the bridge?

That would be simplest. It would also guarantee you know the state after you press the button. If not, all you know is that it has changed.
 

Bluejets

Oct 5, 2014
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Not sure how you can easily get remote operation with a single input.
Possibly you could try a magnetically latching changeover relay?

Easy...if he uses the r/c tx and rx with a servo, traverse to one end closes one of a pair of micro switches, traverse to the other closes the other micro switch. In the centre, neither is operated.

Micro switches set up exactly the same as for reversing a dc motor.
 

mcasey

Jul 9, 2016
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Easy...if he uses the r/c tx and rx with a servo, traverse to one end closes one of a pair of micro switches, traverse to the other closes the other micro switch. In the centre, neither is operated.

Micro switches set up exactly the same as for reversing a dc motor.

Where could i buy one of these?
 

Bluejets

Oct 5, 2014
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BobK

Jan 5, 2010
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I agree with Steve. One of my pet peeves is remotes that have a "power" button. When operating more than one device they will eventually get out of sync and you will turn some on and others off. If they had an "on" button and an "off" button, this would never happen.

Do you have some way of knowing which state the valve is in when you choose to switch it? If not, you will certainly be better off with an "on" button and and "off" button.

Bob
 

(*steve*)

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With more smarts at each end you could encode a single channel to send a start or a stop signal, but effectively boils down to the same thing.
 

mcasey

Jul 9, 2016
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I finally created the circuit to do exactly what I wanted with the exception of one thing, rapid battery drain. I am using a standard 9 volt battery to power the following circuit, and it works great. The problem is, the battery dies after about 24 hours. The L293DNE IC requires 5 volt internal logic. I'm thinking this is the culprit. Can anyone offer a suggestion on how to prevent battery drain? I only use the remote on/off and push buttons on/off a couple times a day for a few seconds, which leads me to believe there's something wrong with the design.


schematic1.png
 
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davenn

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I finally created the circuit to do exactly what I wanted with the exception of one thing, rapid battery drain. I am using a standard 9 volt battery to power the following circuit, and it works great. The problem is, the battery dies after about 24 hours. The L293DNE IC requires 5 volt internal logic. I'm thinking this is the culprit. Can anyone offer a suggestion on how to prevent battery drain? I only use the remote on/off and push buttons on/off a couple times a day for a few seconds, which leads me to believe there's something wrong with the design


Those small pp9 batteries have VERY small capability. you are going to need something with much more capability ... a rechargeable 12V 7.2 Ah gel cell etc
 

Alec_t

Jul 7, 2015
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According to the datasheet the minimum supply current of the L293D is 10mA (with all outputs at high impedance).
What is the standby current of the two voltage regulators?
 

Gryd3

Jun 25, 2014
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Check out the previous answers as well, but if you want longer battery life you need your circuit to me more efficient, or you simply buy a bigger batter or an AC-DC adapter.
Do a quick search for battery capacity too for a cell you want to use.
9V cells typically have 500mAh unless you use rechargeable cells. You can also pay extra for lithium.
In any case, it would seem fair to estimate a constant 20mA draw from your device if it dies in 24 hours.
Confirm the details asked above, and let's see how we can best solve this.
 

mcasey

Jul 9, 2016
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I'm thinking I could add a relay to the L293DNE in order to disconnect pins 1, 8, and 16 until one of the switches is pressed. Thoughts on this?
This still leaves the problem of current drain for the RF part of the circuit. Any way to drop the Receiver/Decoder to a ultra low current state until a button is pressed on the transmitter?
 
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