Can someone confirm my circuit makes sense?

I'm hoping to make a shield using one of these boards - Cytron Arduino Proto Shield - RobotShop

Just want to make sure everything is where it's supposed to be, and any suggestions for changes or added components for protection/improved signal would be appreciated!

I'm new to fritzing so please be gentle, hopefully it's somewhat coherent.

Couple points to note - the temperature sensor is actually a DS18B20 and the "pressure sensor" is a 4-20ma type. I couldn't find those on the component list so just used something with the same outputs.

What is the reason for using a 24v battery..?

bluejets:
What is the reason for using a 24v battery..?

It's a PSU I'm using to run my pump and arduino

The fuse is overkill, the 7805 has an overheat-shut down, mind you with such a big stepdown you are going to need a heatsink even if the current you are drawing is going to be small. I am assuming that you will use a 7805, though a buck converter would be a much better choice. If you are going to use a pump on the 24v rail, i suggest a choking coil on the GND line to the electronics, and between the 24v power supply and the regulator a diode, and a capacitor of at least 10uF, and beyond the regulator another 1uF one (although the Arduino has one on the board)

Deva_Rishi:
The fuse is overkill, the 7805 has an overheat-shut down, mind you with such a big stepdown you are going to need a heatsink even if the current you are drawing is going to be small. I am assuming that you will use a 7805, though a buck converter would be a much better choice. If you are going to use a pump on the 24v rail, i suggest a choking coil on the GND line to the electronics, and between the 24v power supply and the regulator a diode, and a capacitor of at least 10uF, and beyond the regulator another 1uF one (although the Arduino has one on the board)

Hi Deva, thanks for the reply. I should have specified, I am in fact using a buck converter, here's the datasheet - OKI78SR

Can you explain where I should put my diode and why? Will have a google of choking coils

Can you explain where I should put my diode and why? Will have a google of choking coils

Both are meant to steady the power supply, the choking coil to remove any unwanted ac- spikes that the pump may put out, the diode and the capacitor behind, to have an energy storage that can not be drained by the pump, but is available to the converter (if you say regulator, i assume lineair)

Deva_Rishi:
Both are meant to steady the power supply, the choking coil to remove any unwanted ac- spikes that the pump may put out, the diode and the capacitor behind, to have an energy storage that can not be drained by the pump, but is available to the converter (if you say regulator, i assume lineair)

How do I go about speccing a choke? I tested the windings of the pump at 21 ohms recently so max current should be around 1.2 A, I don't have a scope to verify though. Other than current rating is there anything I should be looking for?

E2A: Also, I assume the choke just goes in series with the earth before it gets bonded?

E2A: Also, I assume the choke just goes in series with the earth before it gets bonded?

The choke may not be required, but i would put it between the GND and GND of all electronic parts with the exception of the pump. he idea is to filter any noise that the pump may put out onto the GND line. Let's not worry about the choke but put a Fly-back diode across the pump instead, that will probably suffice.

Deva_Rishi:
The choke may not be required, but i would put it between the GND and GND of all electronic parts with the exception of the pump. he idea is to filter any noise that the pump may put out onto the GND line. Let's not worry about the choke but put a Fly-back diode across the pump instead, that will probably suffice.

I was just reading about these actually, is this the same as a TVS diode? I read that suppression devices should be as close as physically possible to the load although I don't entirely understand why - in the pumps case will the end of my leads suffice? (probably about 200mm)

trojanhawrs:
I was just reading about these actually, is this the same as a TVS diode? I read that suppression devices should be as close as physically possible to the load although I don't entirely understand why - in the pumps case will the end of my leads suffice? (probably about 200mm)

Recently watched a video on freewheeling diodes and in that, at least, an ordinary 1N4001 ( if I remember correctly) worked much better than a TVS diode.

bluejets:
Recently watched a video on freewheeling diodes and in that, at least, an ordinary 1N4001 ( if I remember correctly) worked much better than a TVS diode.

Flyback Diode to Protect Relay - YouTube

The ones that came with my arduino pack appear to be 1N4007s surprisingly, which look to be rated for a fair old draw.

The ones that came with my arduino pack appear to be 1N4007s surprisingly, which look to be rated for a fair old draw.

Those 'll do, yeah no big surprise that those came with the pack, they are very multi-purpose, and can be used to build rectifier bridges (even on mains power) and take up to 1A.

in the pumps case will the end of my leads suffice? (probably about 200mm)

should be OOk, the idea is that any device that is coil driven (like a motor or a relay) can cause a short burst of voltage in reverse direction, which then can be drained back by the diode before it damages (or just interferes with) any of the other electronic parts.