4,5 volt regulator

[zapped]

Is there any way to build or purchase a 4.5 volt regulator?

[Th232]

Going to need more information here before I can suggest anything.

1) Input voltage range?
2) Crrent draw?
3) Are you fine with a linear regulator, or do you want a switching regulator? The former will only step down the voltage and will lower the voltage by dissipating the extra power as heat, while the latter is generally larger and uses more components but more efficient.
4) Size constraints?

Oh, and welcome to CPF!

[Norm]

Is there any way to build or purchase a 4.5 volt regulator?

LM317
3-Terminal Adjustable Regulator
Norm

[zapped]

well basically will be using this with two cr123 protected batteries so 7.2v's and need it to be small as possible....using it for an e-cigarette mod.

[Th232]

Without knowing anything about e-cigarettes, I take it that the device won't be drawing a lot of current? In that case I'd second Norm's suggestion of the LM317 or a similar regulator. Nice and compact, especially if you're happy working with SMD components.

That said if it is drawing a lot of current I suppose I should let you know that it could get quite hot, which I suspect is one part of a normal cigarette you don't want to duplicate.

[zapped]

Thanks, am attempting to construct a commercial mod that's durable, not overpriced and small in size.Am more than a little electronically retarded so I might have to bother you guys for more technical help as I go about putting this together.

[JHM]

Simple low power regulation can be achived with a single NPN transistor and a voltage reference, referred to as an emitter follower circuit.

The voltage at the emitter of the transistor will be the same as the voltage applied to the base (minus about 0.7V)

The wikipedia entry for "Linear regulator" has a good example (scroll down to "simple series regulator") where R2 is your load, you can also replace the zener diode with another resistor if your precision does not need to be high.

I have built similar circuits, and have had good results up to a couple hundred miliamps, after that the regulation deteriorates, the transistor starts to complain,and it would be better to use a LM317 or other more complex (reliable) circuit

[COAST]

Just go on radioshack.com and search "7805" That's a 5 volt regulator thats pretty small.

[Illum]

4.5 is not a common voltage for logic chips, its directly in the middle of 3.3/5
A super simple way is to use 4.7V zeners you can pair with a LM7805....or use a high powered diode to drop 0.6V off of 5...that makes 4.4 but make sure the LM7805 is heatsinked. also, Linear regulators have a output-input differential of about 1.25V, meaning you cannot use the LM7805 to provide 5V if your input voltage is 6.3V or less
besides, why 4.5V? if your thinking of 3AAA than I can tell you that under load those cells are probably around 3.5V

Simple low power regulation can be achived with a single NPN transistor and a voltage reference, referred to as an emitter follower circuit.

Heres a good read on emitter follower circuits, while its zener controlled series regulator but the concept is the same
http://www.circuitstoday.com/zener-c...age-regulators
I've built similar circuits for low current switches...should higher current applications be necessary one could always use it to switch a bigger transistor