Is this possible?

[Karaethon]

Heres a question, I know I can use a transformer to alter voltages in an AC line, and I know there are regulators to control DC voltage. One thing I noticed is that the regulators need a higher input voltage than the desired output voltage, so in other words a regulator is a sort of Step Down system. now is it possible to step-up voltage? is ther aregulator out there tat would take, for example 12Vdc input and output 16Vdc?

 

[Styx]

look into DCC converters

what they basically do is take a DC, make it into an AC waveform and then back to DC

 

[chemelec]

Look up an LT1371 or an Lt1372 They Boost and Regulate. Can also invert.
Or an LM7660, a Voltage Doubler and or Inverter.


The LT1372 is on my Website as a Project.
The LT1371 project is coming soon.

 

[Karaethon]

Ok, now my next question, related to this one, If I have a 12V Brushless DC fan, is it safe to run >12V into it to for more speed? I know that in regular electric motors you can go up to 10%(i think it was 10%) overvoltage safely and get a result of greater Torque and RPMs, but since these are not regular motors would over volting them boost their rotational speed or just burn them out?

 

[audioguru]

Why do you think a manufacturer would have a max voltage rating for a product?
Maybe because a higher voltage will burn some of them out?
Maybe because a higher voltage would reduce its life?

I wonder why a user would use a voltage that is higher than a max rating. Mmmmm

 

[Karaethon]

I wonder why a user would use a voltage that is higher than a max rating. Mmmmm

Simple, as I stated inn my post above, standard AC and DC motors, you know the industrial type, can be supplied with a Higher then normal voltage to overdrive them. overdriving them so they will output above 100% normal.This is why I was asking, I was thinking that if, in an emergency situation where, the fan speed is already at 100%, but the device being cooled by the fan is not cooling off, then increase the voltage to 110%-120%. this would of course speed up the fan and, hopefully, cool the device down to a safe range where once we could once again drop the fan speed below 100%.
As stated above, this is possible with a standard motor, and I was wondering if it would be possible with a Brushless DC motor.

 

[audioguru]

It sounds like your motor doesn't have enough power (rating) to safely handle emergency situations.
What would happen to the heating device if the motor burned out or seized?

If the device heats too much which requires more fan power to cool it, then why would the fan power requirement decrease? I think it would just stabilise at running at a power that is higher than normal.

 

[Karaethon]

well I dont have this problem, my cooling system is efficient enough that my fans can cool enough, but I was thinking in a worst case, something drastic failed, type of situation.

 

[DigiTan]

I don't know if this will help, but when I was doing an electric RC project I noticed the motor rpms were actually lowered if I applied voltages more than 0.5V above the rating. This was with a brushed motor, geared down by 3.75.

 

[audioguru]

I was thinking in a worst case, something drastic failed, type of situation.

Most circuits use a circuit breaker, a fuse or a polyswitched fuse. I don't think a fan makes a good fuse.
IC voltage regulators and some audio power amps use protection circuits like themal shutdown and fold-back current limiting.

 

[audioguru]

I don't know if this will help, but when I was doing an electric RC project I noticed the motor rpms were actually lowered if I applied voltages more than 0.5V above the rating. This was with a brushed motor, geared down by 3.75.

Maybe its windings heated which increased their resistance.

 

[Nigel Goodwin]

It's commonplace to overdrive motors for short periods, particularly in fighting robots as used in Robot Wars etc. Often they use 12V motors overdriven by 24V or even 36V - this gives far greater power, at the cost of shortening the life of the motor - but for the short bouts they 'usually' survive.

 

[Karaethon]

... but for the short bouts they 'usually' survive.

Well at least the Winning robot survives. :twisted: