A power circuit for my first project


hi everyone, my name is Marcos.

I have some programming skills, but I am just starting with electronic circuits.
It’s my first IoT project and I would like to build (one more) automatic watering system for my plants.

I decided to use a Photon and to write a webapp to monitorize and control the system.

I need to power a 12v/9v water pump and the photon itself.

I have been reading many tutorials but I have not found much information about power circuits.

My idea is to connect the power source to the pumb through a relay, convert the power with a power converter and connect with 5v to a particle power shield and to plug the photon and a battery to that shield.

I whould like to power off the whole system (disconnecting the battery) with a switch because I want It to be portable.

I whould like to start/stop the battery charge with a switch, so I need to install a switch to disconnect the power of the battery shield too.

So please can anybody tell me if that is correct? and ¿What kind of switches and where should I put them?


The Particle Power Shield is rated for 7-20VDC input and is already meant to connect and charge a LiPo battery.
What do you mean with “power converter”? If your 12V supply is AC, you will need an AC/DC converter plus filtering, but if you already have (acceptable) 12VDC, you won’t need the extra bit.
Also why a “battery shield” when the PPS already is such a thing?

To disconnect the battery from the shield, you’d splice in the switch into the red wire of the battery - or I’d rather make a “adapter” wire with the switch that goes between the two JST connectors on the shield and the battery.



first of all, thanks a lot for your response. The power converter that I was talking about is:

But I didn’ know that the PPS was rated for 7-20VDC. Sorry.

When I say battery shield, I really meant PPS. Sorry again.

So I don’t need the power converter and :

I should splice a switch in the red wire of the battery to power off the system.

I should splice a switch (red wire too) between the 12v DC power source and the PPS to start/stop the battery charge.

Is it right?

Thanks again. Regards¡¡


Here is some info about the Particle Power Shield

If you want more detail, you can look at the open source hardware repo


Breaking the wire between battery and PPS alone will prevent battery charging but allows the rest of the system to still run off of 12VDC.
Breaking the 12VDC power line only will also prevent charging but keep the system running off of LiPo.
Breaking both will power down the system (and of course also not charge the battery :wink: )


Thanks a lot.

Now I have to buy the components and start playing with them.

I will use GROVE sensors from seeedstudio: as I told, I have no skills soldering or mounting electronic components.

I am very interested in Particle’s hardware because of their cloud services.

I really want to write a nice web-app to control the hardware, store data and visualize every thing with nice graphs.

Best regards.


@Marcos, you may want to start by drawing a circuit diagram to be clear on how and what you will be wiring up. I would suggest using a proto-board for as much as possible and keep soldering to a minimum until you have proven your design. If you share your circuit diagram we can tell you if everything looks good before you start building it. :wink:


I know I have to draw my design. Please be patient with me, cause I have no much time. I will do it and I will share It here.
Thanks alot for your support.


Hi everyone,

I have had a busy week, so I have just finished my drawing. My idea is not to use a proto-board but using a Photon baseboard from seeedstudio. The GROVE sensors will be connected without soldering.

It’s my first drawing and I hope It represents my idea.

Thanks for your suggestions¡


@peekay123, finally I could draw my circuit. I would appreciate any suggestions.

Thanks a lot¡¡