Well the sort of applications you list are just what variable power supplies are made for. They even have a pot, internal voltage reference, often come with additional features like constant current operation and unflappable output short protection. No need to use an expensive and ill suited audio power amplifier for this task when you can likely buy one or more well suited power supplies for relatively modest money. Topward and several others make good cheap supplies, old HP supplies are often a good bet, rugged and over built, and still working + 20 years on..
Hello guys,
"Take your laptop. Suppose you did set up a 100watt amp that runs on -/+50 volt rails to deliver say 19 volts at 4 amps into a laptop.
Think of the heat the amp will dissipate. It would be around 120 watts. Its just not workable."
Yes, it's 105w rms in 4 ohm, but after rectification the value of wattage will increase enough for powering the laptop, right ?
Those speakers with lights flashing to the sound of the music must be cool !
"Take your laptop. Suppose you did set up a 100watt amp that runs on -/+50 volt rails to deliver say 19 volts at 4 amps into a laptop.
Think of the heat the amp will dissipate. It would be around 120 watts. Its just not workable."
Yes, it's 105w rms in 4 ohm, but after rectification the value of wattage will increase enough for powering the laptop, right ?
Those speakers with lights flashing to the sound of the music must be cool !
Not exactly...
The laptop would draw whatever current it needed, and that assumes the supply feeding it is at least capable of that current requirement.
If you set an amplifier up to deliver a given output voltage then you need to subtract that voltage from the DC supply rail value in order to get the voltage dropped across the output transistors. Multiplying that voltage by the current drawn will give the power dissipated in the amplifier.
That all assumes a normal class AB type design.
The laptop would draw whatever current it needed, and that assumes the supply feeding it is at least capable of that current requirement.
If you set an amplifier up to deliver a given output voltage then you need to subtract that voltage from the DC supply rail value in order to get the voltage dropped across the output transistors. Multiplying that voltage by the current drawn will give the power dissipated in the amplifier.
That all assumes a normal class AB type design.
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