This page (revision-18) was last changed on 2019-12-23 11:17 by Murray Altheim

This page was created on 2019-12-23 04:14 by Murray Altheim

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Power Supplies...nobody
PowerSupplies

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At line 20 added 4 lines
Shown below is a portion of the table from the [Raspberry Pi FAQ|https://www.raspberrypi.org/documentation/faqs/#pi-power]. There's also a table showing typical power usage "during standard processes" (which doesn't include driving your robot up a steep incline). They define a "stressed" Raspberry Pi 3B as using 1.34 amps. Stall current on a robot motor can be 5 amps. Most robots have at least two motors.
Hmm. Clearly we need to think about this a bit more.
At line 28 removed 4 lines
The above is a portion of the table from the [Raspberry Pi FAQ|https://www.raspberrypi.org/documentation/faqs/#pi-power]. There's also a table showing typical power usage "during standard processes" (which doesn't include driving your robot up a steep incline). They define a "stressed" Raspberry Pi 3B as using 1.34 amps. Stall current on a robot motor can be 5 amps. Most robots have at least two motors.
Hmm. Clearly we need to think about this a bit more.
At line 72 changed one line
products. Apple seems to be the worst: they sell two adapters (listed as the ''Apple 87W USB-C Power Adapter'' and the ''96W USB-C Power Adapter'') that are likely the most expensive on the market and are not showing their output ratings in watts but seemingly their power ''requirements'', i.e, not what they __deliver__ but what they __use__. Of course it says nothing about this on the box. It's 87 watts, right? [{Image src='PowerSupplies/5w-adapter-thumb.png' link='https://support.apple.com/library/content/dam/edam/applecare/images/en_US/accessories/Adapters/5w-adapter-tech-spec.png' caption='Apple 5 watt USB adapter' alt='Apple 5 watt USB adapter' align='right' class='imgFloatRight'}]
products. Apple seems to be the worst: they sell two adapters (listed as the ''Apple 87W USB-C Power Adapter'' and the ''96W USB-C Power Adapter'') that are likely the most expensive on the market and are not showing their output ratings in watts but seemingly their power ''requirements'', i.e, not what they __deliver__ but what they __use__. Of course it says nothing about this on the box. It's 87 watts, right?
At line 78 changed one line
[{Image src='PowerSupplies/12w-adapter-thumb.png' link='https://support.apple.com/library/content/dam/edam/applecare/images/en_US/accessories/Adapters/12w-adapter-tech-spec.png' caption='Apple 12 watt USB adapter' alt='Apple 12 watt USB adapter' align='left' class='imgFloatLeft'}] To give you an idea of how far this is off from that advertised 87 watt promise, delivering 87 watts at 5 volts it should be delivering __17.4 amps__. Apple's unit is clearly using 87 watts to deliver 15 watts (3 amps at 5 volts) of power. You can check this yourself by using an online [Watts to Amps Calculator|https://www.rapidtables.com/calc/electric/Watt_to_Amp_Calculator.html] or [Amps to Watts Calculator|https://www.rapidtables.com/calc/electric/Amp_to_Watt_Calculator.html].
To give you an idea of how far this is off from that advertised 87 watt promise, delivering 87 watts at 5 volts it should be delivering __17.4 amps__. Apple's unit is clearly using 87 watts to deliver 15 watts (3 amps at 5 volts) of power. You can check this yourself by using an online [Watts to Amps Calculator|https://www.rapidtables.com/calc/electric/Watt_to_Amp_Calculator.html] or [Amps to Watts Calculator|https://www.rapidtables.com/calc/electric/Amp_to_Watt_Calculator.html].
At line 80 removed 2 lines
What's strange is that Apple has delivered honest reporting on its other units. Their tiny 5 watt unit delivers 5 volts at 1 amp. Their 12 watt unit delivers 5.2 volts at 2.4 amps. They provide technical specification for these smaller models, but the "Tech Specs" for the 96 watt model just says "USB C". What gives?
At line 85 added 3 lines
[{Image src='PowerSupplies/5w-adapter-thumb.png' link='https://support.apple.com/library/content/dam/edam/applecare/images/en_US/accessories/Adapters/5w-adapter-tech-spec.png' caption='Apple 5 watt USB adapter' alt='Apple 5 watt USB adapter' align='left' class='imgFloatLeft' style='margin-right:2em'}] What's strange is that Apple has delivered honest reporting on its other units. Their tiny 5 watt unit delivers 5 volts at 1 amp. Their 12 watt unit delivers 5.2 volts at 2.4 amps. They provide technical specification for these smaller models, but the "Tech Specs" for the 96 watt model just says "USB C". What gives?
At line 96 added one line
[{Image src='PowerSupplies/12w-adapter-thumb.png' link='https://support.apple.com/library/content/dam/edam/applecare/images/en_US/accessories/Adapters/12w-adapter-tech-spec.png' caption='Apple 12 watt USB adapter' alt='Apple 12 watt USB adapter' align='right' class='imgFloatRight'}]
This page (revision-18) was last changed on 2019-12-23 11:17 by Murray AltheimTop