Yeah, theres worse places; try going into abduls and asking for a high power TIP NPN silicone transistor of 121 or above rating. great kebabs tho
LOL! i prefer kebab king across the road for me 'babs personally (oh no - its a vimto/bina thread again )
if u can im moving uni. a kebab shop that sells electronic components and stays open until yer on the way back from the pub
That circuit won't drive a fan. You've got the motor connected as an emitter-follower after a 555 on a 5v supply, so at best the pulses will only be 4.3v peak. You could move the motor to the top side of the transistor, but it's still a simple 555 astable, so don't expect great results. You need at least a dual-555 or add a comparator for proper PWM. If you want a single 555 circuit, use Nomad's.
kk. i didnt get nomads before i started this and still dont, but ive more confidence to try the circuit now
WHy not use this circuit instead? It uses a pot to control a fan, and cuts out the Grrrr Grrrr Grrrrrrr noises you can get with PWM controlers: VR1=4k7
Cant i just use a 5v LED? itll be easier? although im not sure of that lighty transistor thingy :S looks simple though Dunno, might have a go at nomads although im sure to get that wrong too Thx for all the help btw.
Correct. Its like a variable relay. The brighter the LED, the more voltage is let through the PhotoTransistor. So basically it does the exact same as the 555 PWM circuits without the pulsing and growling and complexity MMM-HEY.
But with the very high gain of your darlington TIP122 you'll not get any sensitivity of control, and it will vary with the rating of the fan on the end. Simplest possible fan controller:
might have a crack at: seems easy enough ill need to rig up 5 within the same box so a phototransistor thingy wont work i think. I dont mind heat output - ive got 20odd Xeon heatsinks here doing FA so they can be cut up and places in a row along the trannies only question now is - can i cut the length of the rod on the pot down to fit a knob on it??
cool Cpemma - reading ur site you say this: What about putting a 100uF cap in between 12v and ground to stabilise the input?
You can never have too much ram or too much smoothing Certainly won't hurt on any add-on electronic gizmo.
i made it and it works although: the fan slows down waaaay too quickly on the rheo anyway to graduate it further? change the resistor?
Not really thats the disadvantage, its becasue of the transistor, i'm workign on a way to correct it, but its gonna be a while (If at all)
nm m8, ill try other things i think btw - caps dont half go pop!! It was only 100uF and i stuck it in backwards by mistake it kinda expanded... then POP! i need a new pair of trowsers - i dont think brown suits me
LMAO, i've done that so many times. Remember kids, allways be careful when inserting Electrolytic Capacitors into your circuits
