the useful gadget thread

crossedwires

Chirping
10 Years
Jan 19, 2010
127
0
99
well maybe useful
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, i have been reading thru the forum with interest and noticed people having a couple of problems with a few things that are fairly simple to solve with a couple of home built gadgets.
for example alot of people seem to have small polybox home made bators with pc fans to move the air. out of those a few people would like to alter the speed of the fans and that got me a thinking
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so if enough people are interested i will show you step by step how you can build fairly simple controllers to accomplish such tasks. first off tho to make it as easy as i can i will stick to readilly availiable components (anologue) so as many people as poss can join in, i did think about making a thread to include microcontroller gadgets because with a microcontroller you can make just about anything, but the down side is you need special hardware to program the chips, you need the abillity to write software and you need a fair amount of electronic knowledge........so lets stick to anologue so anyone can join in.

back to the fan controller....................
you can (and many do) controll the speed of a fan with a simple variable resistor but it has drawbacks, mainly the fact its very inefficient and you loes alot of torque (the fans abillity to turn) also it can get the components very hot etc.
if you were doing a speed controller with a microcontroller you would use a technique called PWM (Pulse Width Modulation) wich in very very simple terms is switching a device on and off at very high speeds, the adavantage of this is you get better controll of speed and you loes virtualy no torque.
after thinking about it for a while it occured to me that anyone who was able to use a soldering iron could make a pwm fan controller with a few simple components. it wont be as great as a microcontroller but you can get very very good results and you end up with a variable speed fan.
there are a alot of gadgets you can build simpley with a few components so if enough people are interested (i dont want to waste my time on something noone wants!) i will do step by step tuts with circuit diagrams etc and verio board layouts and pics etc so people can build a few gadgets, i will build each one myself as well so i can show you how they work.
so what do you all think??? anyone interested or any questions?

i should also point out that i will keep them as cheap as possiable. most should be under £10
 
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ok lets get the weekend out the way and i will start posting mon or tuesday. for the first project i am thinking 2 versions the MK1 and ....er Mk2 MK1 will be just a simple variable controller for a pc type fan that will run continously. the MK2 will be slightly more involved (not much) but will allow you to adjust speed and have the fan pulse on and off at different rates, like i said before i wont use anything like a microcontroller for theese projects that way more people can build them. i will start posting on mon. for this project we will use the tried and trusted 555 timer to alter the duty cycle, the MK2 will use 2 555 timers and probaly something like a 4017 decade counter, all theese parts are very very cheap and easy to get hold of but more on that later. apart from that it will just be a couple of resistors and a few caps ect.
 

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