On 02/01/2020 16:57, Toby Newman wrote:
> On 2019-12-20, nev young  wrote:
>> On 19/12/2019 13:02, Toby Newman wrote:
>>
>>
>>> This is a good present idea for my mum or sister.
>> Hi Toby.
>>
>>> How do you power it?
>> I power mine from an old (ie redundant) laptop power supply to deliver
>> ~ 19volts down a length of 10A two core cable. The sort used for hedge
>> trimmers or lawn mowers. I use such a high voltage and thick cable to
>> compensate for the voltage drop of the longish runs to the garden.
>>
>> At the camera end, this (highish) voltage is fed in to a buck dc-dc
>> converter eg. https://tinyurl.com/vbbbv8f  This delivers a good steady
>> supply of 5volts to the pi Zero W, camera and LEDs.
>> ( nb. DO NOT USE A 7805 voltage regulator. It'll get way too hot! )
>
>
> Cool, so do I have this right:
> Connect the 19V across the inputs, then a large
> resistor across the outputs, and use a multimeter to watch the voltage
> drop across the large resistor while twisting the potentiometer with a
> screwdriver until it matches 5V, then replace the resistor with the
> Raspberry Pi?
>
staggeringly bad way to do it

read what he said.
"this (highish) voltage is fed in to a buck dc-dc converter eg.
https://tinyurl.com/vbbbv8f  This delivers a good steady
supply of 5volts to the pi Zero W, camera and LEDs."



--
“Ideas are inherently conservative. They yield not to the attack of
other ideas but to the massive onslaught of circumstance"

    -  John K Galbraith

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