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Raspberry Power DC Power Supply

gadget.iom

A recent discussion by Robin Gunning (Raspberry pi powersupply change from micro usb to dc power plug) led me to investigate the feasibility of creating a board allowing a DC power jack to be connected to the Raspberry Pi.

 

 

I have created my first ever Eagle Schematic but would appreciate some feedback on the suitability of the design and any comments/suggestions you may have for improvements or potential pitfalls.

 

image

The aim is to have a 26-way extension header so that shields can be added on top of this board. The 26-way header should also be compatible with the 40-way header on the newer plus editions of the Raspberry Pi.

 

Thanks

Paul

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  • Hi Paul,

     

    Your design on its own looks fine (just an EAGLE thing, if you use the 'Net' icon instead of the 'Wire' icon to draw your wires, then it will automatically add blobs at junctions; the 'wire' icon need  never be used in a schematic, although it works electrically just like the Net icon) and will definitely function. But looks like you've got to grips with EAGLE quickly overall.

     

    The only concerns are (1) If you use a (say) 9V DC supply, then around 2W of power is dissipated if the RPI consumes 5V 500mA since (9-5) * 0.5 = 2W (the RPI may use less power, the 500mA was a guess). 2W is a enough to get a small heatsink hot : (

    and (2) lack of schematics for the RPI B+ make me uncomfortable wiring to the pins like this, although in theory it should be fine

    and (3) might be worth double-checking the pinout of the 7805, most models have pin 2 as the ground, not pin 3, but I wasn't sure which package you were using, so it may be fine.

     

    So to summarize, (assuming the pinout of the 7805 is correct) in practice this board would probably be fine, as long as a (say) 7V supply was used (although that may be borderline for a 7805) or with a heatsink.

  • in reply to shabaz

    Thank you for that . I will replace the wires with nets and look into the 7805 heat concerns and pinout.

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