I’ll preface this with a warning. I’m not a qualified electrician, nor do I claim to have any remote understanding of electricity, life, the universe or anything else for that matter. If you choose to copy me, you do so at your own peril! Now that’s out of the way. Here is the kit you’ll need to build this project!
- 240v to 24v Transformer
- 5mm x 2.1mm Barrel Jacks (Male)
- Heat Shrink Tubes
- Tri-Core Cable
- UK Plug
- Electrical Terminals
- Ultrasonic Mister Heads
- Multi Meter
You’ll also need odd’s and sod’s like screwdrivers, strippers/plyers and crimpers! Have a rummage in your toolbox!
When using multiple ultrasonic mister heads, you’ll find it becomes a pain in the bum. You have to have a transformer for each head, they’re hot and bulky and you don’t feel safe leaving them on overnight. I had this problem too and decided to alleviate it by combining the transformers into one big one.
You can buy multi headed ultrasonic misters, ranging from 3 – 24 heads from places like House of Hydro, eBay, Ali Express etc.. but these always struck me as big investments. These range from £100+ for the smaller models and if one goes wrong, your whole mister operation goes down.
This is a good example of the reviews these products have https://www.amazon.co.uk/FORAVER-Ultrasonic-Humidifier-Transformer-Gardening/dp/B07G85GRTR
I prefer to ‘spread my eggs’ as well as pay less. If you’re careful with your budget, this can be cheaper and better than anything you can buy on eBay because this is modular. If one head goes wrong you can replace it instantly vs the whole unit going down.
In this guide we’ll be making a 4 head transformer, though I run 6 comfortable and I suspect 10 wouldn’t be an issue. Just make sure your transformer can handle the load. Most mister heads are around 12 – 25watts so make sure you figure out if the number of heads + wiggle room is suited with the appropriate transformer.
Start by attaching your plug to your tri core wire. Then strip back the 3 ends of the same wire to plug into the transformer.
Once stripped, crimp on some terminals. I’m using 14 – 16 AWG terminals but you can choose the ones that work best for you! You should really be using rings to prevent them pulling out but I didn’t have any so fork it is!
You’ll see on the front of the transformer or even on the plastic lid that there are markings. From left to right we have the resistor adjustment, V+ which is 24v DC + output, V- which is 24v DC-, 240v earth, 240v neutral, 240v live.
Secure the brown to live, blue to neutral and green and yellow to earth. Make sure that this is correctly wired. Make sure it is secure. I am not an electrician – do this at your own risk, make sure you understand what you’re doing before you do it.
Ensure the screws are tightly screwed down.
Once you’re happy that everything is correct. Stand back and plug it in to make sure it works! Make sure the little plastic cover is down.
Next, strip back about 1cm of wire on each of the male barrel jacks.
Split the two wire sleeves apart from each other about 1/3rd of the way up.
Twist together the tips of the wires, make sure you’re twisting together the corresponding wires i.e. solid red with solid red and black and red with black and red.
Crimp on a terminal to the two twisted wires. Again, use rings if you have them.
Sleeve over some heat shrink tubing to protect the connection further. This is because it’s a high stress point, it’s where it will receive the most flex. I’m doing these in banks of 2 jacks but you could get away with banks of 3 or more, just remember to do your maths and not overload your transformer, as well as this, avoid any sharp bends/pinches in your cabling as this is where hot spots form.
Attach the red cables to the V+ on the output and the black and red cable to the V- on the output. Make sure the transformer is disconnected before attempting any electrical work and that the current has dissipated.
Sleeve a bigger heat shrink tube over all the cables to keep them tidy.
With a multi meter, test the output of the unit is around 24v. Any higher, it will kill the ultrasonic mister heads, any lower they won’t work at peak efficiency. Adjust the voltage with the resistor by using a screwdriver and twisting it up or down
Using a homemade float, made from plant pots and children’s play-mat foam, test your unit to make sure everything is working properly with your mister heads. Just make sure your misters are covered with the right layer of water, you can fine tune this by adding or taking away weight to the float or raising/lowering the mister inside the pots until you find the sweet spot.
Success! You did it. Good job. I keep my misters in a self contained/sealed box with a fan blowing in and a pipe leading out. This way it doesn’t splash everywhere and my mist is contained into a stream where I can duct it to where I need it to go. Be sure to isolate the transformer, put it inside another plastic box and keep it safe, just make sure it has holes so it can cool itself! Have a look through the photos below. Thanks for reading!