By: Tillmann (IP: 146.140.7.*)
Written on: 25-07-2005 17:37
I have a hard time believing n-channel MOSFETs are hard to get / that expensive in Australia; it's really a common part.
For example, check out RS Components (international company, they're popular here in Germany, too); they have an Australian online shop:
NPN and PNP transistors are BJTs (Bipolar Junction Transistors) which are technically much different and will definitely NOT work as an alternative.
A J-FET _might_ work, it's theoretically possible, but I've never tried it. If those are cheap, why not get one and give it a try, if they are available at a local shop (not sure what you mean by "local" - one near your house where you can just walk in and buy the transistor, or one that is at least located on the same continent ). But, you must make sure that you get an n-Channel J-FET as well. I also have some doubts as far as the capability to supply enough power to the fan is concerned (read: the J-FET might burn out).
J-FETs have source, gate, drain too, so just wire it up like you would wire the MOSFET.
Any opinions from other readers here?
By: ben (IP: 211.28.95.*)
Written on: 26-07-2005 17:00
I also live in Australia.
Did you find a 10k ntc? dse.com.au only lists 100k. Does this make a difference to the circuit since it is adjustable?
By: Xenendith (IP: 220.253.92.*)
Written on: 28-07-2005 15:52
I've found another Electronics store that sells a more than adequate Mosfet for about AU$2.00 which is annoying but acceptable i suppose. (seeing as I want to controll around 4 - 5 fans... better than buying an already made one, and not nearly as fun)...
As for the NTC... A website called jaycar.com.au sells them for about a Buck each wich is good.. and they've got a dealership nearby so i should be able pick all that I need from there (saves me having to post it here )... For all the Aussies out there I'm about 1 hr's drive north of brisbane.. on the sunshine coast...)
I'll give you what I've found,
MTP3055E 12A 60V Power Mosfet --- AU$2.00 each X 5 (CAT. NO. RN3440)
(Would this one work?)
Thermistor NTC 5MMDIA 10KR --- AU$0.95 each X 5 (CAT. NO. RN3432)
10K 16MM POTENTIOMETER LINEAR SINGLE GANG --- AU$1.75 each X5 (CAT. NO. RP7510)
And LED's/PCB/Switches etc etc.
Just one more thing.. I want to try to incorporate some sort of indication of how fast the fan is spinning... my first thought was a tri coloured (2 pin) LED I know they exist and I can find them.. I've just got no idea how they work... If anyone knows then I'd love to know... So I was thinking that I could setup a group of 3 led's WIth different Ohm resistors so they light up at different voltages???
I'm no electrician (done a bit of electronics) but I'm not sure if my idea is even possible... Alternately I could use an orange lamp and just use the intensity to guage how fast they're spinning but leds are Better