Alternate Power DC-IN on the Euler Bus also with PI filter for batt operation
#11
   

In this post I have remade the PI low-pass filter so that it can be replicated more easily;  I'm using the Sparkfun solderable mini breadboard and the same components from my previous board-- I've just moved them over to the new board which mimics physically (more precisely) the schematic in the pic above;  the left hand cap is the storage cap, and the right hand cap is the smoothing cap.  The inductor is in the positive feed;  while it does not matter which end of the board is input and output the larger of the two caps would typically be the output end;  in my version the caps are both the same. 

   

The mini solderable breadboard is similar to the plastic pluggable ones; the five vertical pins in each column on the top are connected together; similarly , the five vertical pins in each column on the bottom are connected together.  The components will be moved so that the positive rail is at the top and the negative rail (ground) is at the bottom.

         

The pics above are the new board; top and verso.  The black edge of the board is negative, and the red edge of the board is positive;  it is very important that the electrolytic capacitors are connected to the positive and negative rails in the right orientation (the neg lead has the silver band) or else they will explode when the power is connected !

   

The pic above is the finished PI filter connected for use with the Rock64 board, or the Pinebook.  Remember check twice, plug once;  reversing the polarity of the wiring is disastrous for the capacitors !
marcushh777    Cool

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#12
         


The pics above are a rework of the PI filter on my PineA64 desk board.  In this case the schematic has been modified to have two caps in parallel on either side of the inductor, which on this board was wound by hand.


         


The pics above are the final mod including bleed resistor and indicator LED.  These are the larger 5mm LED(s) with ballast for 18ma.

   


The last pic above is the PI filter installed and running on the PineA64 desk board, showing the proper connection to the euler bus pin(4  +5v) and pin(6  ground).
marcushh777    Cool

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#13
(08-10-2016, 03:09 AM)MarkHaysHarris777 Wrote: In the pic above we are looking at an alternate method of powering the PineA64 with DC-IN on the Euler Bus; +5v on pin(4), and ground ( - ) on pin(6).  

In this pic above white is common (ground) and black is 5v ( + ) the 'hot' wire.  Electrically, pin(2) and pin(4) on the Euler bus are connected to DC-IN on the micro usb power jack (see schematic pp6 of (19));  if a person is careful, either method may be used to provide 5v power to the PineA64 board.  WARNING:  do not do this if you are not sure of your skills, nor if you are unsure of the theory. Check with someone skilled before proceeding.

There are a couple of reasons why you might want to connect DC-IN with this alternate method:  1) you may want to provide your Play Box with a 5v barrel connector for charging,  2) your power supply is only rated at 2.0A (5v) and you want to shorten the supply line and bypass the weaker micro usb connector,  3) you want to make a more solid power connection perhaps with a [ toroid | cap ]  low pass filter for use in an auto  or with other dc-dc converter. 



Normally I do not recommend this method; because it has the potential for making mistakes;  only connect 5v on DC-IN, never reverse the polarity of the wiring (always check, never guess);  that said, this method does provide an alternative for routing DC-IN for those who have the skills and know what they are doing. 

WARNING:  If you're looking at the schematic(s) pp12 of (19) the 5v on pin(8) is NOT a DC-IN pin;  pin(8) is a 5v output pin only.  The only DC-IN pins are pin(2) and pin(4).  Any ground pin may be used for ground; however, pin(6) is convenient for the purpose.

Do you know if this also works on the Rock64?
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#14
(07-29-2017, 05:44 PM)MarkHaysHarris777 Wrote:  


The pics above are a rework of the PI filter on my PineA64 desk board.  In this case the schematic has been modified to have two caps in parallel on either side of the inductor, which on this board was wound by hand.

The only change I would recommend is adding a couple "faster" ceramic capacitors given that electrolytic caps have high internal resistance (ESR value) and are considered "slow".

Also a flyback diode on the coil to protect against voltage spikes when unplugged.
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