Here is the auto power shutdown IR Board.https://www.amazon.com/gp/product/B06X9 ... UTF8&psc=1Burngate wrote:The Pi 3B requires quite a lot of current, and so does the screen (a real time clock won't want much)
It might help to know which Auto Power shutdown board you have, and also the power adapters you are trying to use.
Before I had the Markefocus board installed the screen and the Pi 3 and screen were powered with the Screen supplied Y splitter. Also what is strange is that the MarkerFocus won't work unless the splitter is installed. Even without it powering both the Pi and the screen. So I guess three power supplies is needed. I am at a loss.Burngate wrote:Well, this might not be much help.
The Pi requires at least 4.65v - below that the red LED goes out and the lightning bolt appears.
I haven't yet got a 7" screen - I'm wanting one but I'm too tight-fisted - so all I can go on is what I've read here.
The USB hub says it only takes a few mA, but will obviously take more depending on what's plugged into it.
If that main PSU is doing what it says it should, 3.5A should be plenty. It should be fully capable of driving both Pi and screen, though there seem to be differing experiences depending on whether the Pi feeds the screen or vice versa.
But having 6.5ft of lead makes me suspicious - it's rather long, given that the resistance of the lead can drop the volts quite drastically if it's thin or long.
What the Makerfocus auto shutdown board does is anyone's guess. Hopefully it doesn't drop the voltage to the Pi etc. too much.
OK yes it is a USB micro cable splitter. Here is the link to the Official case for 7" and cable. https://www.amazon.com/gp/product/B01HK ... UTF8&psc=1Burngate wrote:You've mentioned twice the power splitter that came with the screen. I've looked at the Pimoroni, CPC and RS pages, but none mention a splitter, so I'm at a loss as to what you mean.
I'd assumed it was a short USB to two USB Y cord, so that nothing much could be affected by it, but I must be wrong.
Time, I suppose, to fork out sixty quid and see for myself.
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AWG Ω/km Ω/m Voltage drop @ 2A and 4m 16 13.17 0.01317 0.105 17 16.61 0.01661 0.132 18 20.95 0.02095 0.167 19 26.42 0.02642 0.211 20 33.31 0.03331 0.266 21 42.00 0.042 0.336 22 52.96 0.05296 0.423 23 66.79 0.06679 0.534 24 84.22 0.08422 0.673 25 106.2 0.1062 0.849 26 133.9 0.1339 1.071 27 168.9 0.1689 1.351 28 212.9 0.2129 1.703