Hi Eric,
Hope you don't mind me placing a message on this thread.
Firstly I wanted to say fantastic work on your proton pack build and the gubbins that go inside it. It's admirable to see how you help so many fellow enthusiasts and certainly a lot of the posts have helped me. I've read through all of this thread after having come across your post initially on thingiverse and then GitHub.
![Image](https://i.imgur.com/dN6KXpk.jpg)
![Image](https://i.imgur.com/650vjGD.jpg)
![Image](https://i.imgur.com/IIzn8PK.jpg)
![Image](https://i.imgur.com/zT7NQjG.jpg)
In time I will post further pictures of where I am with my build. In short I've performed the following so far.....
1. 3D printed, prepped, painted and weathered both the proton pack and wand and mounted the pack to motherboard.
2. Got most of the electrics mounted and running on breadboards with 12v 3a mains power for now. Will be eventually going to a 11.1v 3S high mah lipo.
I've made some modifications to the 3D prints to allow for metric parts in the UK (i.e. pvc tube adapter, cable connectors between wand and pack) and some custom brackets to hold the single LEDs and jewels. Also improved on the design of the Legris elbows and straight couplers to be more bold and less delicate.
I've also introduced a new button at the end of the wand to change the colour of the wand firing and changed the flashing sequence when the wand jewel is firing. Also where there is a lens on top of the wand (but no LED) next to the vent I've introduced a green LED to show when the proton pack is powered up and the slo-blo is steady on. All mods I've done not for authenticity but to give my build a personal touch.
The last bit of electronics to be sorted is related to hooking up a relay to power both the air pump and vape pen atomiser.....and I'm stuck.
![Sad :-(](./images/smilies/icon_sad.gif)
I've added the code for the relay and using an LED at the moment to simulate the relay off pin 13 and am satisfied all is ok code wise.
My problem......
I have sub-ohm vape atomiser (Smok vape 22 pen). Upon reading up the required voltage is 4.2v and the resistance is 0.25ohm.
Based on my calculation that is a possible 16.8amps that can be drawn. I=V/R. (4.2/.25)
The air pump is 4.5v. I'm thinking I could run both via a buck converter through a relay.
(I bought a pack of x3 buck convertors - One for the (Arduino nano + sound fx) and the other for the amplifier with one spare.
I need a relay that has a high amperage rating at 5v (say 20a+) and not sure on the schematics for wiring up both the air pump and atomiser.
Do I need to drop in a resistor or two to protect each item?
Would I wire up the pump and atomiser in series or parallel?
What is the best to use a relay or MOSFET?
If so could you point me in the direction of what would be suitable please and advise on the schematic required.
Andy