Gerymake
Posts: 46
Joined: Sun Jan 06, 2019 11:38 pm

Soldering jumper wires to solenoid valve

Wed May 08, 2019 6:37 pm

Hello,

I have to solder two jumper wires to connect a solenoid valve (https://www.adafruit.com/product/996) to my breadboard. Unfortunately, all the wires I have are thiner than those of the valve. Therefore, I don't know wheter I may have heating problemas...

As far as I know, it shouldn't suppose a problem, I won't be drawing a lot of current (3A at 12V). What do you think, is it a viable option?

Thanks in advance,
Gerard

PD: I know it is a horrible soldering job.
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pcmanbob
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Re: Soldering jumper wires to solenoid valve

Wed May 08, 2019 6:53 pm

Well they look like dupont cables so I would guess 28AWG which will carry about 1.5A , so trying to put 3A through them will result in a big volt drop at best and the cable to get hot if you valve is on for any length of time,
You breadboard will not like it either as they are commonly rated at 5V at 1A or 15V at 0.3A so 12V at 3A might cause it to fail and/or get hot.
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Gerymake
Posts: 46
Joined: Sun Jan 06, 2019 11:38 pm

Re: Soldering jumper wires to solenoid valve

Wed May 08, 2019 8:35 pm

It would be on for very short periods of time. A few times a day maybe, it is just for a garden automation project. Anyway, what would be the better approach to this?

This is the wiring diagram, I am using the breadboard for prototyping, when I have checked everything, I will move it onto a perfboard.
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PhatFil
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Location: Oxford UK

Re: Soldering jumper wires to solenoid valve

Wed May 08, 2019 9:31 pm

Having used a similar valve I think those wires would get hot if carrying a full load for longer than 10 seconds or so?..
My whoe valve starts getting Hot after 2-3 minutes running (via an opto isolator and relay)

perhaps substitute a 12v bulb for breadboard testing if testing 'opening the valve' for any significant length of time..

Gerymake
Posts: 46
Joined: Sun Jan 06, 2019 11:38 pm

Re: Soldering jumper wires to solenoid valve

Thu May 09, 2019 12:41 pm

PhatFil wrote:
Wed May 08, 2019 9:31 pm
Having used a similar valve I think those wires would get hot if carrying a full load for longer than 10 seconds or so?..
My whoe valve starts getting Hot after 2-3 minutes running (via an opto isolator and relay)

perhaps substitute a 12v bulb for breadboard testing if testing 'opening the valve' for any significant length of time..
Let me see if I understood properly. I should test the circuit with a 12V bulb. Afterwards, when I move the circuit to a perfboard, I could install the solenoid valve normally.

PhatFil
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Joined: Thu Apr 13, 2017 3:55 pm
Location: Oxford UK

Re: Soldering jumper wires to solenoid valve

Thu May 09, 2019 2:23 pm

Gerymake wrote:
Thu May 09, 2019 12:41 pm
Let me see if I understood properly. I should test the circuit with a 12V bulb. Afterwards, when I move the circuit to a perfboard, I could install the solenoid valve normally.
Yes, exactly. you can test the valve directly with a suitable 12v dc supply, and use a low power 12v bulb in the breadboard circuit to validate the wiring and system design etc. So you can be confident when 2 x proven aspects are adjoined in a finished solution.

Gerymake
Posts: 46
Joined: Sun Jan 06, 2019 11:38 pm

Re: Soldering jumper wires to solenoid valve

Thu May 09, 2019 7:57 pm

PhatFil wrote:
Thu May 09, 2019 2:23 pm
Gerymake wrote:
Thu May 09, 2019 12:41 pm
Let me see if I understood properly. I should test the circuit with a 12V bulb. Afterwards, when I move the circuit to a perfboard, I could install the solenoid valve normally.
Yes, exactly. you can test the valve directly with a suitable 12v dc supply, and use a low power 12v bulb in the breadboard circuit to validate the wiring and system design etc. So you can be confident when 2 x proven aspects are adjoined in a finished solution.
Thanks for your help!
Gerard

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omegaman477
Posts: 148
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Location: Sydney, Australia

Re: Soldering jumper wires to solenoid valve

Mon May 13, 2019 10:40 pm

Put a decent electrolytic capacitor between the +12VDC power rail and ground, close to the FET (observe polarity) say 50VDC/1000uF. The solenoid will have a huge inrush current which could collapse the power rail enough to spike out the RPI.

Testing with a globe is fine, but remember the solenoid is an inductive load not resistive, but I see a flyback diode in your circuit.
..the only thing worse than a stupid question is a question not asked.

Gerymake
Posts: 46
Joined: Sun Jan 06, 2019 11:38 pm

Re: Soldering jumper wires to solenoid valve

Tue May 14, 2019 2:33 pm

omegaman477 wrote:
Mon May 13, 2019 10:40 pm
Put a decent electrolytic capacitor between the +12VDC power rail and ground, close to the FET (observe polarity) say 50VDC/1000uF. The solenoid will have a huge inrush current which could collapse the power rail enough to spike out the RPI.

Testing with a globe is fine, but remember the solenoid is an inductive load not resistive, but I see a flyback diode in your circuit.
I read about that, or at least I think so. Such devices will experience a high variation of current in a short periode of time, therefore, to prevent spikes I have to install a 1N4001 diode. Is that what you mean?

Video which explains it perfectly: https://www.youtube.com/watch?v=ioSYlxHlYdI (1:19)

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