3.3V on a 3V device?
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From: David Nebenzahl on 8 Mar 2010 18:20 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. What say the experts here? (I also thought about bringing the voltage down to 3 volts with a 0.36 ohm resistor, or maybe a couple diodes in parallel: need to drop 0.3 volts, and the camera draws 2.5 watts [0.86A), so 0.3/0.86 = 0.36 ohms. Maybe 3 1N4001s in parallel?) -- You were wrong, and I'm man enough to admit it. - a Usenet "apology"
From: David Nebenzahl on 8 Mar 2010 18:23 On 3/8/2010 3:20 PM David Nebenzahl spake thus: > (I also thought about bringing the voltage down to 3 volts with a 0.36 > ohm resistor, or maybe a couple diodes in parallel: need to drop 0.3 > volts, and the camera draws 2.5 watts [0.86A), so 0.3/0.86 = 0.36 ohms. > Maybe 3 1N4001s in parallel?) Scratch that business about using diodes. Dunno what I was thinking there (or not thinking) ... -- You were wrong, and I'm man enough to admit it. - a Usenet "apology"
From: Sjouke Burry on 8 Mar 2010 18:30 David Nebenzahl wrote: > On 3/8/2010 3:20 PM David Nebenzahl spake thus: > >> (I also thought about bringing the voltage down to 3 volts with a 0.36 >> ohm resistor, or maybe a couple diodes in parallel: need to drop 0.3 >> volts, and the camera draws 2.5 watts [0.86A), so 0.3/0.86 = 0.36 ohms. >> Maybe 3 1N4001s in parallel?) > > Scratch that business about using diodes. Dunno what I was thinking > there (or not thinking) ... > > carefully check (with noload and full load) the voltage of the wart. You might be lucky and use it, as long as it stays between ~2.7 and ~3.4 volts, but most warts surprise you in a rather unwanted way, and you better stay away from them....
From: Samuel M. Goldwasser on 8 Mar 2010 19:17 Sjouke Burry <burrynulnulfour(a)ppllaanneett.nnll> writes: > David Nebenzahl wrote: > > On 3/8/2010 3:20 PM David Nebenzahl spake thus: > > > >> (I also thought about bringing the voltage down to 3 volts with a > >> 0.36 ohm resistor, or maybe a couple diodes in parallel: need to > >> drop 0.3 volts, and the camera draws 2.5 watts [0.86A), so 0.3/0.86 > >> = 0.36 ohms. Maybe 3 1N4001s in parallel?) Parallel diodes don't reduce the voltage drop significantly. There are diodes that have a much lower voltage drop so one of those might be acceptable. > > Scratch that business about using diodes. Dunno what I was thinking > > there (or not thinking) ... > > > carefully check (with noload and full load) the voltage of the > wart. > You might be lucky and use it, as long as it stays between ~2.7 and > ~3.4 volts, > but most warts surprise you in a rather unwanted way, and you better > stay away from them.... If it's a switchmode adapter - light as a feather - then it's probably regulated at the nameplate voltage which I assume to be 3.3 V from the subject line. But if you know or can measure the current and its reasonably constant, the resistor will work. -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs.
From: William Sommerwerck on 8 Mar 2010 19:26
If you're using a regulator, there shouldn't be a problem. And you can always stick a silicon power diode in series with the /regulated/ output to drop the voltage 0.6V or so. |