3.3V on a 3V device?
in [Repair]
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From: Arfa Daily on 10 Mar 2010 21:20 "David Nebenzahl" <nobody(a)but.us.chickens> wrote in message news:4b97e503$0$2357$822641b3(a)news.adtechcomputers.com... > On 3/10/2010 9:48 AM Arfa Daily spake thus: > >>>> On 9 Mar, 00:20, David Nebenzahl <nob...(a)but.us.chickens> wrote: >>>> >>>>> I'm wondering if running a 3-volt device (cheap digital camera) on 3.3 >>>>> volts will hurt it. Yeah, I coulda gotten a 3-volt wall wart to run >>>>> it, >>>>> but it was expen$ive. The 3.3V regulator I got was a little more than >>>>> a >>>>> buck. Haven't tried it yet. >> >> There's nothing wrong with the diode route to drop the voltage by a >> (reasonably) constant amount, but just use a Schottky type, which will >> have a forward voltage drop of around 0.3 to 0.4v - or just about what >> you're looking for ... > > Can they handle the current (~ 1A)? Of course they can. All switchmode power supplies, including those that provide many amps of output, use such diodes as their secondary-side rectifiers ... Arfa
From: Franc Zabkar on 10 Mar 2010 22:45 On Mon, 08 Mar 2010 15:20:07 -0800, David Nebenzahl <nobody(a)but.us.chickens> put finger to keyboard and composed: >I'm wondering if running a 3-volt device (cheap digital camera) on 3.3 >volts will hurt it. Yeah, I coulda gotten a 3-volt wall wart to run it, >but it was expen$ive. The 3.3V regulator I got was a little more than a >buck. Haven't tried it yet. Unless the 3.3V regulator is a fixed type, it may be possible to bring it down to 3.0V by changing a feedback resistor. Can we see a photo of the PCB? - Franc Zabkar -- Please remove one 'i' from my address when replying by email.
From: David Nebenzahl on 11 Mar 2010 00:38 On 3/10/2010 7:45 PM Franc Zabkar spake thus: > On Mon, 08 Mar 2010 15:20:07 -0800, David Nebenzahl > <nobody(a)but.us.chickens> put finger to keyboard and composed: > >>I'm wondering if running a 3-volt device (cheap digital camera) on 3.3 >>volts will hurt it. Yeah, I coulda gotten a 3-volt wall wart to run it, >>but it was expen$ive. The 3.3V regulator I got was a little more than a >>buck. Haven't tried it yet. > > Unless the 3.3V regulator is a fixed type, it may be possible to bring > it down to 3.0V by changing a feedback resistor. Can we see a photo of > the PCB? It's just a TO-220 regulator, for chrissakes. An NTE something something .... don't have it here at the moment, but it's just a fixed 3.3V regulator. So no, not possible to rejigger it w/a resistor. I'm just going to use it as-is. I don't think 10% overvoltage will hurt the cam. -- You were wrong, and I'm man enough to admit it. - a Usenet "apology"
From: William Sommerwerck on 11 Mar 2010 08:10 > Unless the 3.3V regulator is a fixed type, it may be possible > to bring it down to 3.0V by changing a feedback resistor. One assumes that a 3.3V regulator is a fixed regulator (or otherwise the OP would not be having a problem). Fixed regulators' outputs can be changed, too, but only raised. This is usually done by inserting a Zener diode in the ground-reference line. (CMIIW.)
From: Franc Zabkar on 14 Mar 2010 17:20
On Wed, 10 Mar 2010 21:38:23 -0800, David Nebenzahl <nobody(a)but.us.chickens> put finger to keyboard and composed: >On 3/10/2010 7:45 PM Franc Zabkar spake thus: > >> On Mon, 08 Mar 2010 15:20:07 -0800, David Nebenzahl >> <nobody(a)but.us.chickens> put finger to keyboard and composed: >> >>>I'm wondering if running a 3-volt device (cheap digital camera) on 3.3 >>>volts will hurt it. Yeah, I coulda gotten a 3-volt wall wart to run it, >>>but it was expen$ive. The 3.3V regulator I got was a little more than a >>>buck. Haven't tried it yet. >> >> Unless the 3.3V regulator is a fixed type, it may be possible to bring >> it down to 3.0V by changing a feedback resistor. Can we see a photo of >> the PCB? > >It's just a TO-220 regulator, for chrissakes. An NTE something something >... don't have it here at the moment, but it's just a fixed 3.3V >regulator. So no, not possible to rejigger it w/a resistor. > >I'm just going to use it as-is. I don't think 10% overvoltage will hurt >the cam. I thought that a standard 3-terminal regulator with a 1A current limit may not be appropriate for the task. That's why I assumed you had something more sophisticated. After all, you did get the camera for $1. :-) - Franc Zabkar -- Please remove one 'i' from my address when replying by email. |