30v DC Input to Remotely Variable DC Output 5v to 30v

Found this ...they have the remote controls for up to 50'....

http://www.kbelectronics.com/Variable_Speed_DC_Drives.html

...or are you maybe in this area...?

http://www.hobbytron.com/RCHelicopterParts.html

$20

http://www.hobbytron.com/RadioControlHelicopters.html

It is unefficient (and overheating) to control a motor by varying its voltage, you should seek to do it by modulating the duty cycle.

A voltage regulator won't help too much, and if your fan is brushless type, then it might not work at all, these guys have an internal driver board which produces a revolving magnetic field in the stator coils to rotate the permanent magnet rotor.

Regards

A buck converter is a switch mode supply:-

http://en.wikipedia.org/wiki/Buck_converter

And sounds ideal for the job (excepting your comment).

GA

Google LM317 (LDO version, if you need the max. output really close to 30V).

But with any kind of linear regulator, you'll be wasting a lot of power - at least

(current x (30-Vout) will be lost as heat).

What current is the fan drawing? This will help in determining what to suggest.

As stated in another post the switching power supply is the easiest and probably cheapest way to go. Even a wall wart might be usable if the current is within the range of the motor.

Good Luck, Old Salt

Thanks Old Salt

About 3 amps

Because you are going to use capacitors instead of a battery on the input you need a Buck/Boost switcher.

Go to the Digikey site; do an initial search for PMIC; then select DC DC; then narrow your search: start by selecting all the buck boost switchers <Apply Filters>; next choose all with 3A and above <Apply Filters>; continue to narrow the search input volts→ output volts → etc.

What do you have against S.M.P.S.s? They and their derivatives are simply the best way to go nowadays...Its only highly sensitive electronics that may not play ball, but remember most PCs have such a power supply......

Even if it was a "noisy" SMPS, which it shouldn't be, a motor will hardly notice the difference anyway....

Someone (Yahlasit) else posted correctly, that changing the voltage is a bad way to control a DC fan or motor, he was right!! Modulation is the only way to go with full voltage.....good starting, good speed control and no problems with "sticktion" (spelling may be off!).

Also remember that if you go too low with the power/voltage, the motor may heat up and windings may get damaged. It might even stall.....

I tend to stop at about half the voltage for simple things like chip cooling. I do it simply by having say two identical tiny fans in series, each one capable of using the full available voltage....motors usually start well, but run very quietly and having two gives a good flow of air.

I also have done it in my caravan for oven and fridge cooling, with bigger 12 volt and mains fans, thats right, 4 in all!! Did it 14 years ago....still works well....

I did this to my hard disk Sat receiver a few weeks ago.....now its "cool".....

For you, you do need to identify exactly the motor type as pointed out already, before starting!!

Someone else mentioned RC Heli controllers, thats a great place to start.....if the motor can handle such controllers, also usually efficient and if the voltage "fits"....