I made bad experience with 5V POE splitter. Most of them I tested have far below 5V output.
My conclusion is, that I use splitter with 12V output and place a variable 5V step-down after it.
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tnx for the tip, I was also wondering ’ how come that the advised RPI power supplies are 2A and these POE splitters a lot less, doesn’t that give problems ?
Impressive tool at a bargain - but of course still high - price
Battery powered Spectrum Analyzer, VNA, Power meter, Cable Analyzer, Signal generator and very complex LTE over the air analysis 100 kHz to 4Ghz
They also stock much cheaper ones but with accuracy or other problems (they do describe the problem) e.g. https://www.ebay.co.uk/itm/JDSU-Gencomm-GC747A-LTE-Spectrum-Cable-Antenna-Analyzer-Signal-Gen-S332D/263677568409?hash=item3d64686599:g:e9EAAOSw8nxa9P3
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Regarding the “active” PoE stuff - its all crap in my opinion. The “real” PoE equipment is not that much more expensive, you get real PoE Splitter for 15 Euros (like the TP-Link TL-PoE10R Splitter) and they are IEEE 802.3af compatible, so you can use them with a wide range of PoE Injectors or Switches compatible with IEEE 802.3af or 3at. I got several of the TP-Link ones running in TTN/LoRaWAN Gateways based on RasPis without any problems (for month on cable length >30m).
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Nordic nRF51822 Multi-protocol Bluetooth® 4.0 low energy/2.4GHz RF SoC
32-bit ARM Cortex M0 processor (16MHz)
16kB RAM
256kB Flash
Bluetooth Low Energy
5x5 LED Matrix Bildschirm
Beschleunigungssensor,Gyroskop, Magnetometer (Bosch BMX055)
MEMS Mikrofon
DC Motortreiber (TI DRV8837)
Piezo-Lautsprecher
Programmierbare RGB LED (WS2812b)
2 programmierbare Taster
Serielle Schnittstelle (USB + konfigurierbare Anschlüsse)
PWM Ausgabe
4 Bananenstecker/Krokodilklemmen-Anschlüsse
4 Analoge Eingänge
8-11 Ein-/Ausgangsanschlüsse (je nach Softwarekonfiguration)
SPI + I 2 C
USB Micro B Anschluss (Programmierung und Stromversorgung)
JST Batterieanschluss (3.3V)
Bananen/Krokodilklemmen-Anschluss für 3.3V (Ausgang)
2 Grove Steckverbinder (I 2 C + Seriell/Analog)
Flash-Programmspeicher (optional)
US $3.18 incl. shipping
US $3.30 incl. shipping
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US $4.99 incl.shipping
US $1.58 + $0.39
That was the luxury version I think!. Mine was without text on the red switches. It was “recycled” and bits and pieces of it are still floating around on the attic. But you sure learned how to write efficient assembly code and the processor manuals are still on my bookshelfs. Anything after that was spoiling memory, speed, battery, etc. Moore’s law could only barely compensate for the experience of having soldered that one together and got some lights flashing 
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Yeah, it was a great (and disciplined) learning experience. Making a mistake could often result in having to enter major part or all of your code again (tens or hundreds of instructions in hex).
And each program had to be manually entered. Only 1 kB ram and no external storage. No SSD, no flash drives, no harddisks, no floppies, no NAS, no network, no internet, zilch. I did build the cassette tape recorder interface that was published in Elektor but never got it to work successfully.
It was unique that we programmed directly in binary code, manually! 
No programming language, no compilers, not even assembly language. Assembly instructions, but we had to lookup their hex code in the processor manual and then enter the binary (hex) code.
The photo above is not from my own Junior. I haven’t taken any photos from my own unfortunately (in those days with film based cameras it was not common to make photos of your electronics).
I had built mine into a nice enclosure and had made an extension PCB with 16 LED’s (2 8-bit PIO ports). I made those LED’s light up in every thinkable (programmable!) pattern an sequence.
I sold my Junior long ago, to buy my first computer with an ASCII keyboard: the Acorn Atom.
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0.45€ delivered. Beat that ! 
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