Linear PC Fan Speed Controller Stripboard Veroboard Layout

Extremely simple fan speed controller.

the input voltage depends on the fan you're using however the fan I used is a 12 volt fan so mine is powered by a 12 volt power supply.

I made this for a soldering iron fume extractor however it will work for your PC fans too and I plan on using it in mine.

here is a good video by fixitdaz on a very similar circuit

Temperature Controlled Fan Controller Stripboard Veroboard Layout

I built this for 2 things - 1. my computer is getting a little hot and I like quiet for as much as is possible so having a little automatic controller turning on a few fans when it gets too hot is ideal for me. and 2. my homemade power supplies could do with fans and again I don't want them running all the time but with this particular temperature sensor LM35DT as it is a TO-220 package you can screw it to the heatsink you have your regulators on (with the usual isolation of course) so the fan only runs when the regulator gets abit hot.

(v)R3 controls at which heat the fan will turn on at however it is a little tricky to calibrate so it will be a case of trial and error unless you have known heat sources.

I also used a TLC071 OP-AMP for a couple of reasons 1st. it is a single supply op-amp so I didn't have to piss about with dual supplies etc. and 2nd I got it free from Texas Instruments excellent sample service

I used a TIP41A because that's what was nearest to my hand. I know the schematic says TIP41C but it doesn't really matter - the letter designations just refer to the voltage the transistor can handle and none of them go below 40 volts so use whichever you can get or even any similar NPN power transistor will be fine.

Stepper Motor Controller Stripboard Veroboard

This weeks entry is a stepper motor driver. you will notice this has 4 LEDs on the board, this is to stop flyback current from damaging the other semi conductors, they are necessary so don't omit them + you could maybe mount them on a control panel cause the flickering looks cool.

when I made this circuit I used a motor I ripped out of an old HP deskjet so I used the colour code on the wires on the board layout so I have included a stepper motor diagram that shows where the wires actually go so you can use any stepper motor

similar NPN transistors can be used - I just have loads of BC549s


NOTE: pin 14 of the CD4013 is connected to the 12v rail

it is moving, it's just kind of hard to capture the act of movement in a still picture, still kudos to my phone camera for not blurring on movement.

Simple Forward/Reverse Motor Controller Stripboard Veroboard

this is a pretty simple build, I needed something to control a motors speed and direction with just one potentiometer so I came up with this - essentially it is 2 555 timers bridged together so that when you turn the pot one way the frequency on the first one increases and the second decreases and vice versa - it outputs a PWM signal so you may need to use a smoothing capacitor on the Motor (non polarized of course)
when the pot reaches the center position it will stop.
I'm sure this will have many more uses too.