preassembled voltage regulators

[dman762000]

can someone please tell me what kind of preassembled voltage regulatorI need to convert 7.2v (from a tyco TMH flexpack) to 6v, and possibly where I can find one

[tom61]

Err, for that little voltage drop you could just use a resistor. Also, if whatever you need to runs off 6Volts, it would likely run off 7.2Volts anyway.

[dman762000]

I am worried about overvolting my casio tv I am using,,,,,,,those things are expensive and I don't want to blow it up.


Edit: nevermind I didn't want to try it for fear but I did and it seems to work fine with the 7.2 volt makes it a lot easier

Since this is redundant if any mods want to remove it they can

[daguuy]

see if 5v works, it probably will and there's plenty of 5v regulators you could use

[timmeh87]

you couldnt just use a resistor. thats not a good idea.

[Skyone]

A resistor does not actually limit voltage, just current.

Actually, tim, you're smart - maybe you can explain to me this:

Why do you need a resistor when using an LED? I've seen 5v been through a resistor and onto a 3v rated LED, and it ran at 3v, how does this work?

[shmagoogin77]

too much current is the only thing that kills leds

[Skyone]

I thought that components only take as much current as they need?

[SpongeBuell]

hold on peoples, here's how it goes when resistors are givein in series (which you want to do anyway for stuff like this)

First of all, current is drawn, not forced. There is no such thing as too much current, the thing takes what it needs. Current is NOT lost in resistors, it's the same on both ends of the circuit.

Voltage, on the other hand, is forced. Not only that, but you lose voltage when you put electricity through a resistor (the energy is changed into heat) It is entirely possible to fry a component by too much voltage, though it's not as likely if it's only a volt. (but not always the case, especially if whatever it is doesn't go through a regulator)

[timmeh87]

sort of. things take as much current as they 'need' according to the laws of physics, but it is misleading to personify it like that, since things quite often 'need' more than enough power to kill themselves instantly.

take for example a small piece of wire shorting a car battery. it will try to draw something on the order of 100 amps, and almost instantly melt.

leds are the same way.

current is not "lost" in resistors, but resistors do decrease (or 'resist' ) the current. V = IR. assuming voltage is fixed, then current is inversely proportional to the effective resistance, since IR (current multiplied by resistance) has to remain constant (because just now we said that V is constant)

also, LEDs have a fixed voltage drop, and no matter what voltage you hook up to them, you will be able to measure their forward voltage across them (batteries are the same way).

now im not -totally sure- about this, but if its the same as batteries, then the more voltage you give them (even though the forward voltage will remain the same), the more current will try to rush though them. this is a consequsnce of V = IR, but this time R is contant, so its V/I = R; current is proportional to voltage. (if V increases, I must increase to compensate, because it always has to equal R)

so anyways, too much current will kill an LED due to excessive heat buildup (dissiapted heat is propotional to the square of the current), so you want to control that. technically an LED has an 'ideal' current that you can do the calculations for and come up with a resitor value, but realistically anything in the 20-100mA range is ok, and you can just slap a resistor in the 20-100ohm range on there and it should be ok (note: the fact that the range is 20-100 in both cases is just a conincidence, furthermore i just made these numbers up now)

---

yeah sorry that might have been a bit confusing. anyways, one note:

this is all assuming that the LED, wires, and power supply have zero resistance. now, each one of those assumptions is somewhat valid on its own, but put them all together, and use a battery for power (which has high internal resistance), and you are effectively simulating that resistor with the intrinsic resistances of all the components. this is why you can hook up a 3v led to 5v and not have it fry. however, it is 'bad engineering practise' to not use a resistor, and in general you want as little current flowing through your LEDs as possible, because thats part of the mA everyone is so concerned about when talking about battery life.

[codeman]

meh...too lazy to contribute anything more than this:

http://www.benheck.com/phpBB/viewtopic.php?t=12058