- 6-12v Diaphragm Pump
- DC/DC Solid State Relay
- Float Switch
- PWM Voltage Regulator
- 12v 0.5A Power Adaptor
- 2x Panel Mount Female Power Jack
- Male Power Jack
- Project Box
- Nylon Bolts
- Silicone Tubing
- ABS Sheet Plastic - This is best purchased from your local sheet plastic distributor's scrap bin.
- Shrink Tube
- 18 Gauge Wire - Smaller gauge wire could be used but I like to buy 18ga as it's more useful for other projects and this only requires a small amount.
- Drill Bits
- Scoring Knife or Razor Blade
- Metric Tap and Die Set
- Soldering Iron
- Heat Gun
- Wire Cutter/Strippers
Nice to Have:
Drill holes for the inlet and outlet of the pump. When placing these holes remember to leave room for the voltage regulator and relay on one side or the other as seen below.
Then drill holes for the power and switch jacks and mount them into the project box and drill the hole for the voltage regulator. Depending on the project box and voltage regulator you choose you may have to file the PCB a tiny bit to be able to mount it. Again, remember to leave room for your other components. The project box I listed just barely fits these parts.
Next you will solder an extension onto the positive lead of the power jack as well as join the negative side of the power jack to one side of the switch jack and add an extension off of that. I also added some shrink tube to the bases of each jack as the wire connections felt a bit flimsy.
Now you can start hooking up to the relay. The positive lead from the power jack goes straight to the positive terminal of the input side of the relay along with another lead that will be plugged into the voltage regulator later on. Also connect your power jack's ground lead to one side of the output side of the relay (doesn't mater which terminal) and connect a lead to the remaining terminal of the output side of the relay, this lead will connect to the negative side of the voltage regulator later on. And finally connect the remaining lead from your switch jack to the negative terminal of the input side of the relay.
Now you can hook up your voltage regulator.
Solder leads onto the pump and plug them into the power out side of the voltage regulator.
Mount your voltage regulator and slide the pump in and you should have something like this.
Now for the switch! Unscrew the male side of the jack you'll be using for the switch and solder some wire to it. Instead of a positive side and a negative side what we have here is an "in to the switch side" and an "out to the voltage regulator side" that is carrying the negative side of the current going to the pump that is interrupted by the float switches. You can use a tape measure in liew of a third hand.
Now, this would be a good time to check your wiring and also confirm that your float switches are working before soldering everything together. Proper function of the switches can be confirmed by either checking continuity with a multimeter or plugging in the switch and power to the box and listen for the pump to turn on and off while you activate the switches. Great thing about these diaphragm pumps, they're self priming and can run dry all you want. Once you're sure it functions properly solder one side of each of the switches together then the remaining sides of the switch are soldered to your wire you put your male jack onto.
Then I like to cover up the ugly yellow wires with some shrink tube and it will hold the wires at the position they are at when they cool.
I ended up shorting out one of the switches during testing so when I wired a new one in I also added a large piece of shrink over the bolt side of the switch so water is unable to get onto the top side of the switch. When they fail that's how I've always seen it. So doing this will dramatically increase the life of these switches. But also using these longer switches makes it so the water wont even go that high when you turn the return pump off.
And finally the bracket. I happened to have a 1.4" wide strip of ABS for this part of the bracket but if you don't, plot it out on your ABS sheet, score it with your scoring knife and break out your strip. The bend was put into the plastic by heating the area I want to bend with the heat gun then wrapping around the rim of the tank I'm making it for.
Drill and tap.
Drill and tap.
Next plot out an L shape for the next half of the bracket.
Drill the holes for the float switches and create the adjustment slot for mounting to the other half of the bracket. The slot is achieved by drilling two holes and cutting out the slot by scoring and scoring until you can push it out.
Clean it up with your files and deburring pen and you should end up with a part looking something like this.
The hole for the float switch is also slotted so you can fit the wire in when you mount or unmount the switch from the hanger.
Then give it a 90 degree bend.
And another one!
And another one!
And you've just made an ATO!
Probably a good idea to also label the jacks and inlet/outlet of the pump.