Great way to get 3.3v

[nos_slived]

I think he just meant it in the sense that the extra energy is lost as heat.

[timmeh87]

yeah.

im all about the efficiency. at some point ill probably try to repalce all the regs in my 64/screen with dc-dc's. but not for a while. id probably get it all working first, so i can do a battery life comparason.

[MaDnEsS]

yeah it only last like 10 min im gettin a dc-dc then all i need is a case

[Gamelver]

how many diodes did you use? AFAIK, most small ones only can take about 100mA of current through them before they get fried. that would mean you'd need around 80 diodes just to distribute the current evenly....so I hoped you learned your lesson, Madness..diodes suck for voltage regulators !!!

(that is, unless you use 'em with transistors...I've only learned about using them with NPN transistors, though, so I'm definitely no expert on building your own voltage regulator )

[MaDnEsS]

i used 5 parrelel it took it down to 3.5-6 it works for testing

[superdeformed]

If you really want to use diodes for regulating the voltage down to 3.3V, then look for a 3.3V zener diode with a high enough power rating. It should work, although they generally aren't intended for high current loads (mostly they're used to create reference voltages, or voltages used for controlling other things with very little current draw). It also wouldn't be anywhere near as efficient as a switching regulator or DC-DC converter. You can find plenty of info on zener diodes, and how to hook them up, on google.

[MaDnEsS]

i said i decieded to get a dc-dc. i was just testing it with the diodes

[nos_slived]

I may be wrong, but from what I remember about zener diodes, they don't lower the voltage, they just block the current in one direction, until the voltage goes above the marked rating. For example, a 3.3V zener diode will block all the current in one direction, unless there's more that 3.3V pushing on it, in which case the full voltage pushing on it goes through.

[superdeformed]

I may be wrong, but from what I remember about zener diodes, they don't lower the voltage, they just block the current in one direction, until the voltage goes above the marked rating. For example, a 3.3V zener diode will block all the current in one direction, unless there's more that 3.3V pushing on it, in which case the full voltage pushing on it goes through.

That sounds about right except for the full voltage part. When the input voltage is above a specific point (usually about 1V above the zener's specified voltage), current can flow through the diode to the anode (in our case ground/0V). The zener keeps the voltage drop across it exactly (well, pretty darn close) at it's specified voltage, which in this case is 3.3V. Since the anode is at 0V, the cathode has to be 3.3V for the drop across it to be at 3.3V. You use a resistor between the power source and the diode to limit the current through the diode and use the voltage at the cathode to power whatever it is you need powered. Obviously with a high current draw there would still be a fair amount of wasted power at the resistor, so it really only makes sense to use this kind of setup with low current loads.

[SNESguy]

Yeah you wouldn't need 80 diodes, because they make HIGHER current rated diodes at values such as 2-4 amps. Radio Shack has them.

-SNESguy

[MaDnEsS]

dude all you need is 5 parralel to take it down to 3.6

[gannon]

As said before, voltage drop differs with different diode types. Also, if you're using low voltage drop ones, you'd need 5 in series, right?

[someone]

what's wrong with a plain LDO voltage regulator?

[S q u e e !]

You confuse me into making me think that I thought I posted when thinking is making it hard for me to think.

See?! Grrr!

**EDIT**

Evil Post Count!

[*o*]

aaaaaaaahhhhhhhhhhh hes the devil!