Arduino to controll serveral motors or PC Fans

mem: really thanks alot i will be back when i get a fan working i wont bother you no more. thanks for keeping it simply. hugs

No bother at all. Please do post the progress with your project.

FYI, Futurlec sells the 2n7000 for .09 each in quantities of 25: And they have the 74HC595 for .50 each.
Shipping is reasonably priced but it takes a least a week so if you are in a rush you may want to get parts locally.

mem: will do but what happens to the power supply ground and negative pole? hugs bern

The FET source legs are all connected together and go to the power supply ground. The power supply ground is also connected to the Arduino ground.

And of course, the positive lead from all the fans are connected together to the +12v output of the power supply.

hi mem is this ok to be made as an extender for arduino?

Yes, the FET power connections look correct

thankyou very much mem but do you think i could make it with 32 connections?

I haven't built something like that so I can't speak from experience but unless someone else sees something that standing in the way, wire up the first block of 8 and give it a go. When you have that working you can wire up the rest.

Have fun!

ok mem i'll have the first board made for 33 euros and i'll post the results

I like to hand wire a prototype before committing to making a PCB. I often find something that I didn't spot on the circuit diagram. It may be worth spending an hour with a soldering iron and some proto board just to make sure.

ok i was thinking about it too bern

hey mem can you help me with the arduino program i hooked up for fans to differents aouputs of the sifhtregister and uploaded to the board the code here. but nothing happens can anyon help

Hi bern,

It's really hard to debug something like this from a distance. But first you should make sure that the wiring to the arduino and 595 matches the code that you are running. If all the wiring is ok (including the power supply and ground lines) then you may want to run a test using a few LEDs on some of the 595 outputs to see if they are being turned on and off. The best advice I can give is to try and devise a tests and measurement for each part of the circuit, starting with the power supply, then the arduino outputs (which are the 595 inputs).

The more you can say about what is and is not working the easier it will be to provide further guidance

hi mem thanks for the reply i am tring to debug but the schematics is like this and the code is in here: as is but i don´t know anyhing about the language tha arduino uses.

can anyone help?

bern, there are a few approaches you can take:

  1. You can test your circuit to see if it is being given the correct signals from the arduino and that the 595 is responding correctly.
  2. You can simplify your circuit to make it easier to see what is happening, perhaps just using a few LEDs to see if things are responding as expected.
  3. You can simplify the code to make it easier to test elements of the circuit.

If you are not yet familiar with writing code for the arduino, this may be a good time to run through some tutorials that start with something simple like turning on and off LEDs and then moving on to driving a few LEDs connected to a 595 shift register.

But if you feel more comfortable looking into the electronics side first, you may want to lay your hands on some tools. If you don't have a logic probe or oscilloscope, you can build them for next to no cost using information on the internet. I think there were some links here a few weeks ago about using a PC sound card a software freely available on the internet for making a low cost oscilloscope. I realize that may seem like a lot of effort before any real progress gets made debugging your project, but I think it was Abe Lincoln that said “If I had eight hours to chop down a tree, I'd spend six sharpening my axe!".

Whatever approach you take, you will need to find some way to verify that the 595 inputs are being driven correctly and determine if the 595 outputs are changing in response to these inputs. If you are not sure what the correct inputs and outputs should be, investing some time reading about the 595 shift register will be worthwhile.

I’ve got a similar set up shown in the picture below. The board in the foreground is a custom job that has 2 595’s and 2 4021’s.

To drive the relays, the ShiftOut code can be used.

Is this what your trying to do?

I’m intrigued by this project, Bern. Are you trying to build something like this (but with fans instead of motors):


mem: as usual you´ve been a great help it seems as if the fan side isn´t working. i replaced a the fans by a led in every output of the 595 and its working.

john_Ryan: yes it something like that i guess

mikal: es its somthing like that but not so limited i guess the main diffence is that the image will be placed in a space like a ceiling or an entire room. I really like daniel rozin work but its not what i want to build. but i guess the system will be similar.


bern, do the fans work if you wire one up directly to the 12 volt power supply? If so, try wiring up a single fan through an FET and see if you can switch it on and off by connecting the FET gate to +5v or ground.

mem: yes do work all by hem selfs. Its ok. but now when i connect the circuit i can hear a slow down on the fans when the siftregister uses passes power but the fans won´t stop. as for the switch on and off by connecting it to the +5V i won´t work the fan will allways stay on. :P