Hi,
I've set out to complete a garden automation project with the aim of improving my overall electronics knowledge (and I'm learing the hard way, more than I thought 
). I'd like to ask several questions, one by one:
1st. I'll be controlling a 12V solenoid valve (Brass Liquid Solenoid Valve - 12V - 1/2 NPS : ID 996 : $24.95 : Adafruit Industries, Unique & fun DIY electronics and kits). At 12V it draws 3A, and here it comes the problem: I can't test it with a breadboard (1A max.). Therefore, I did some research and discovered the perfboard (https://thepihut.com/products/adafruit-bakelite-universal-perfboard-plates-pack-of-10), which can certainly handle this current. But... the solenoid wires won't fit in the holes, they are too thick. What should I do? (I guess reducing the gauge is a horrible idea)
2nd. I'd rather have a power and ground rail, such as a breadboard. Again, I have gone through several sites which provide a wide variety of approaches, which should I chose?
3rd. I may well install a capacitive soil moisture sensor outdoors. I have been recommended to use either conformal coating or silicione to protect the electronics. What silicone type is the most suitable? Should it be a thin cape? Should I take any precautions/any advice? Is the process to be repeated regularly? Can it affect the sensor's performance (Adafruit STEMMA Soil Sensor - I2C Capacitive Moisture Sensor [JST PH 2mm] : ID 4026 : $7.50 : Adafruit Industries, Unique & fun DIY electronics and kits)? All in all, which method would you opt for?
4th. I will have to keep the Arduino board outside. I've come across the idea of building a case (plastic or wood) and sealing it with silicone. The problem is, if there is no air flowing through the case, with the temperature inside, can I have moisture problems which damage the electronics inside?
Aaaaand... that's all. I will make sure to send you some pictures when I get everything ready but, don't you dare ask for my tomatoes! 8)
Thanks in advance,
Gerard
PD: Get back to me if you need further information. Pardon me if there are any mistakes, I'm not a native speaker.
Just put the number of wire strands that will fit into the hole.Wire current carrying rating is based on the melting point of the insulation.
Paul
Or put the wire end flat on top of the perfboard and solder like that. Will do fine as well.
To save the coil from heating you can consider a PWM driven output. Set the thing at 100% at the start, 10-100 ms later (try this) reduce this current. The solenoid will remain open. Find out how much reduction is acceptable before it closes, stay well above that point.
For a constantly powered project (producing heat all the time simply by being on) I prefer the inverted bucket style container - partly open to the atmosphere on the bottom. The heat prevents condensation and the holes stop moisture from building up. A cheap and very efficient solution, I have projects running like that for a long time through typhoons, rainstorms, and periods of 99-100% humidity. No issues. Add conformal coating to stop the last bits of corrosion.
wvmarle:
Or put the wire end flat on top of the perfboard and solder like that. Will do fine as well.
To save the coil from heating you can consider a PWM driven output. Set the thing at 100% at the start, 10-100 ms later (try this) reduce this current. The solenoid will remain open. Find out how much reduction is acceptable before it closes, stay well above that point.
For a constantly powered project (producing heat all the time simply by being on) I prefer the inverted bucket style container - partly open to the atmosphere on the bottom. The heat prevents condensation and the holes stop moisture from building up. A cheap and very efficient solution, I have projects running like that for a long time through typhoons, rainstorms, and periods of 99-100% humidity. No issues. Add conformal coating to stop the last bits of corrosion.
Thanks!
What you mean is, placing the wire flat without inserting it into the hole, and then adding the solder from the bottom? A picture would help (couldn't find anything, I am a newbie to perfboards and soldering).
As for the PWM, is it absolutely necessary? The solenoid will remain open twice a day, during 20-30 minutes non-stop each time, to water the plants. I'd like to keep the budgest as low as possible.
The bucket approach looks perfect! I hand't thought about it, I will definitely give it a try asap and let you know. Lastly, about the power and ground rail, I have read this somewhere else in this forum "Use a bit of stripped cat-5 cable (solid conductor) and lay it along an entire row. When the rest of the component wires are in position then solder the conductor at all the needed holes and a few more if needed to prevent wire bending into adjacent pins on other rows.". I guess I know what he means, but do you have any picture of it, I'm not sure how to search it at Google.
Gerymake:
What you mean is, placing the wire flat without inserting it into the hole, and then adding the solder from the bottom? A picture would help (couldn't find anything, I am a newbie to perfboards and soldering).
Like this. But then maybe with a hole under it, which will quickly fill with solder and cease being a hole.
As for the PWM, is it absolutely necessary? The solenoid will remain open twice a day, during 20-30 minutes non-stop each time, to water the plants. I'd like to keep the budgest as low as possible.
PWM is free - just choose the correct pin of the Arduino, six pins of the Uno/Nano have PWM available. You need a MOSFET driver anyway for that solenoid. Or were you planning to use a (probably more expensive) relay?
My 12V solenoids get really hot after 20 minutes at full power. Untouchable kind of hot. Make sure there's adequate ventilation to get rid of that heat. Throttling power can seriously reduce this.
wvmarle:
Like this. But then maybe with a hole under it, which will quickly fill with solder and cease being a hole.
PWM is free - just choose the correct pin of the Arduino, six pins of the Uno/Nano have PWM available. You need a MOSFET driver anyway for that solenoid. Or were you planning to use a (probably more expensive) relay?
My 12V solenoids get really hot after 20 minutes at full power. Untouchable kind of hot. Make sure there's adequate ventilation to get rid of that heat. Throttling power can seriously reduce this.
Ohhh! I thought it was a module or something like that, sorry. Yes, I was already planning on using a MOSFET. That's all, I'll take it up from here. If I need any further assistance, I won't doubt to come back.
Thanks again!
Gerard
