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Old 27-12-2014, 08:44 AM
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pmrid (Peter)
Ageing badly.

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Join Date: May 2008
Location: Cloudy, light-polluted Bribie Is.
Posts: 3,760
Quote:
Originally Posted by big-blue View Post
Hi Peter
re your questions
Since power = volts x amps, you would appear to need around 48Watts to start and 36watts to run in terms of power requirements.
Firstly a 2Amp rated supply will not attain the required power level. You may also find a significant voltage drop if the supply attempts to exceed its rated current level. You may even over-heat and fry the under-rated supply.
The alternative 10Amp supply should be capable of meeting the required power and running with stable volts and amps. Basically, the load resistance will limit the supply current to 3A when running. In a short circuit situation, however, which is abnormal, the power supply might attempt to deliver its full 10 amps or more and fry itself and/or the short-circuited load. In which case, accidental short circuit represents a risk, and should be protected via (say) a 5A fuse. Short circuits can sometimes arise from (eg) cables that fray over time, or a component which becomes faulty over time. A fuse is the simplest way to protect a (more expensive) load (or supply) from over-current situations however they might arise.
I trust this helps
That is exactly what I needed. Many thanks.
Peter
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