Uno PWM controler question.

First off im new to the site so sorry if this is a noob question. Here is what im trying to build basicly. Id like to use the uno to program a pwm. The system will ran at 12v-14.7v (Backhoe) It will be controling a water pump that draws around 15 amps at max load. Is there an addon that i can use or build to do this? Im aiming for multi function and inputs to control it and finetune its pressure.

You can use something like this schematics with some corrections

Power it with 12-14,7V rather than 24V.
1n4744A replaced by 1n4740A 10V Zener
Use a good sink to protect IRFZ44 from heat.

Thank you very much ill give it a shot.

What is that called?

Low side motor drive, as the transistor connects the '-' of the motor to Gnd.

Copy that CR thank you

Do circuits like this have a name?

Kickergt:
Do circuits like this have a name?

CrossRoads:
Low side motor drive

just wondering… would this schematic be better with changing the buz73 to something that can handle more power?

The diagram that was posted was attached to a post where the poster was having heating issues and a few others as well that i didnt care to read. I finally got my uno and im starting to build my project on the hardware end while i try to learn the programing end as fast as i can without pestering anyone on the board. I dont want to be a pest with my noob questions but i do want to make this project work.

There are lots of parts with very low Rds that would be better:
http://www.digikey.com/product-search/en/discrete-semiconductor-products/transistors-fets-mosfets-single/1376381?FV=1140050%2Cefc0005%2Cfff40015%2Cfff8007d%2C40203a&mnonly=0&newproducts=0&ColumnSort=612&page=1&stock=1&pbfree=0&rohs=0&k=n-channel++mosfet&quantity=&ptm=0&fid=0&pageSize=25&pkeyword=n-channel++mosfet
Such as IRL40B209

so with changing it out with irl40b209 or something like it would the one i posted be a better diagram to fallow vs the first one posted?

I would simplify it even more.

CrossRoads... Thank you so much for your input. Iv learned quite a bit from what you have posted. The damn near infinite way of making electronics do what one wants to do is just mind blowing. So again thank you for all your input and sorry for my EXTREMELY noob questions haha.

For the circuit im attemptnig to build and maybe even someday program im limited on what i have available to me and even more limited on patience haha. It seems like i have enough stuff to make a functional adruino powered PMW that should support the output that im looking for. so here is a small inventory list. If you or anyone could find the time to let me know if im missing something thats a necessity to the project that would be fantastic.

4n35,
TIP3055 and other lower amp units,
1n4007,
Resistors: 1/4watt 100,330,470,1k,4.k,22k,1m and a few others iv been too lazy to ID lol,
Capacitors: .1uf, 10uf, 1.0uf,100uf

A buddy of mine that tried to dabble in this stuff some time ago gave me a box of stuff that he never figured out how to use so i havent ID'd it yet but thats the gist of it. From what i gather from all the different diagrams iv seen over the past week or so i have enough "junk" to take a few steps forward with this.

Thanks again to everyone that helps all of us noobs. I have to say that iv been on and read through alot of different sites on this stuff and many others, and you all here are the best. So from one noob to all you ElectroBadAsses..... Thanks a ton.

Forgot one HAHA should have been by the 4n35

add L293D

mostly basic arduino kit stuff but so far all seems functional for what im attempting to build.

TIP3055 like this?

I'd say you're out of luck. That part is not going to handle 15A for very long.
To get that much current you're going to need 2nd one to supply a huge amount of base current (Ib) and the parts are going to run VERY hot, so big heatsinking will be needed as well. See Darlington configuration

Very hot - power dissipated by the transistor = IV, so 15A x 3V (or more) = 45W.

Is the water pump running in an only on, only off kind of situation? If so, I think you'd be better off with some automotive relays, the 20A kind used for headlights for example.

If you're intending to PWM the pump, then you need to get your hands on some good MOSFETs.
Power dissipated by a MOSFET = Rds * I * I, with a 5mOhm Rds part that's .005 ohm * 15A * 15A = 1 1/8W. Way more manageable. Use a MOSFET driver to really snap the Gate High & Low to turn it On & Off very quick.

Im overbuilding it to an extent for the start. The pump at MAX amp pull so far hasnt gone over 14.7a and on avg after startup is about 6.6amps at continuous load. So i know im at the limits of this unit for now. Once it gets to max pressure the draw goes down.

basicly in the end ill be using a 5v ref to control it and change the on/off points and chose what voltage triggers the max output. I hope that makes sense.

went digging through this box and found a 2n3055 transistor.