LDO Regulators: Good Supplier

Hello all,

Making first posts in an introduction forum is lame so I'll get straight to business.

I'm came across a schematic for a 90W 7.5A fan controller on this forum here and I am going to buying parts to make probably 10-20 of these to use, give to friends, sell, etc.

All of the components I have little trouble acquiring except for the LDO that is being used for the 7.5A version. I normally buy my parts on mouser.com but they didn't have this particular IC (LT1083CP). In fact, the only place I could find with a quick Google search is the Linear Technology (I assume the manufacturer of this IC) website, but they are 8.83$ each for under 100 of them.

Does anyone know of any other electronics suppliers other than mouser.com that might have this IC?

Much appreciated.

umm if your going to go to market, using a Linear regulator is a waste of power, and a heat sync problem, you can PWM now with Mosfets and even clean up the PWM with chokes and Capacitors and you dont need PWM fans to do so, ANY fan can have its power line be PWMed , 2 pin 3 pin or 4 pin. (this has nothing to do with 4pin fans that accept a signal to do PWM internally, they too can be controlled via just the 2 wires)

Plus there is way less dropout voltage (inefficency), so the fans can achieve 98% speed instead of 90%. plus it could handle 30+ amps WHEN switched very very sharply.

you can even do such simple curcuits with parts from radioshack, but it wouldnt be great.
http://www.discovercircuits.com/DJ-Circuits/simplepwm2.htm <--just example of the Many places on the web to get ideas from.

Stage 1: go to any ol electronics store, and get a 555 timer of any sort, and quickly figure out how to get it pulsing and change the duty cycle. have the output go to a cute little LED or something. curcuits for this are all over the web, would take the average person less than a day to get one going. the parts can be all wrong even, and just close enough and you will still get it working, is very forgiving. they put a simple connection schematic on the back of RS packages even, to get you going. and the voltage to run it can vary by quite a bit. a cheap radioshack one can run on the 12v.

Stage 2: then get a cheap mosfet of any kind, and take a few hours figuring out how they work. its just a transister with some different properties. on off on off, pull the gate down pull the gate up, realise what it takes to switch it. you can even put a 12V fan on when on the bench , and see how this all would work. Use any power supply or wall wart, and something that runs on that power. have a few clip leads , and know 3 things. What the In and Out connection points are, and which one is the "gate" that you switch it with.

now you have the basic concept of what the parts do to create pulses and switch power with them.

Stage 3: next combine the output of the 555 to the gate of the mosfet , ok so this isnt so easy to do without tuning the parts (not forgiving) , but now you know what the other parts do, and how they do it. even guessing you could get this worked out in less than one day. and think of the fun you will have

then go buy some very very low resistance mosfets that close with less then .01ohms but avoid the teeney ones if you have the space for them, that way the thing will be more "unbreakable". they go overboard with specs on that stuff, the main thing you need to know is getting a PNP to control the power of the positive line, and that the close resistance is very very low. the power ratings look very high on them, but are only valid with very fast switching (this is important but you will see)

Stage 4: to do an easy cleanup, put a big Fat 16V electrolytic capacitor on the input , then put a big ol fat 16V capacitor on each output, you save power, its still cleaner even. this will address the noise and allow the 3rd pin to read on the motherboard still (at most speeds). add 20 minutes to the project. if you still get noise tune in some ceramic caps on the output , for higher frequencies, but keep the fat electrolytic ones.

Its now usable, and simple

Stage 5: then learn how to use chokes to do a cleanup and eventually reduce the size of at least the output caps.

stage6 : end up with some microcontroller and complicate it 500% and have to debug it for the next 6 months, add in LCD display, 12k of code lines etc etc.
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