Power Supply for the Raspberry Pi

[error0x6d]

I have a RPi Model B. On the board is printed "(c)2011.12". I assume this is the first revision.

I want to use:
- Tontec 3.5 Zoll Raspberry Pi Touch Screen Display Monitor 480x320 LCD Touchscreen Kit (to be bought)
- EDIMAX EW-7811UN Wireless USB Adapter
- Samson Meteorite USB Microphone (to be bought)
- GENIUS SP-HF150 Speakers (to be bought)

and Raspbian. Currently I have a 1.2A PSU. Is this enough, do I have to upgrade or is it not possible?

I am not sure about:
- the max Current on the Micro-USB port
- backfeed powering support on my Pi
- how serious the impact of a usb-charger is (I know that there can be unstable voltages when using a USB-Charger which leads to freezes/shutdowns, but I don´t know if this is a theoretical or a frequently occouring problem or if it depends on the actual used charger)

I need at least 3 USB Powering Ports (for the Pi, the Speakers and a Phone), therefore I would like to have a USB-Wallcharger with multiple Ports (like the "Anker 20W 4-Port USB") as a PSU but I have doubts about the stability of the Pi. Does someone has experience with using such a Supply?

Thank you in advance for your time

[drgeoff]

I would not recommend trying to power all of that from a PSU that is labelled as 1.2 amp. Even if it actually delivers what it claims.

If your RPi is one of the first revisions of Model B with polyfuses in the USB power lines you will need a powered hub for certain for the WiFi dongle.

Are the speakers USB powered? And do they incorporate a USB sound card or do they just have an analogue audio input?

[error0x6d]

Pi + WiFi works fine with the mentioned 1.2A PSU (this is my current setup), but I doubt this is the case if I throw a touchscreen and a mic into the game.

The speakers use the Pi´s audiojack for the signal and are powered seperately by a USB-cable. One of the reasons I tend towards a Multiport USB charging device as PSU

[FTrevorGowen]

I have a RPi Model B. On the board is printed "(c)2011.12". I assume this is the first revision.
...

That's probably a "B2" and therefore should not have the (extra) two USB (140mA) polyfuses, but should have two "mounting" holes and, probably, 512MB of memory (some exist with 256Mb).

Although I have used and tested some multi-output USB power supplies/chargers (not the one you refer to) eg:
http://www.cpmspectrepi.webspace.virgin ... 9202-MICRO
http://www.cpmspectrepi.webspace.virgin ... rt_USB_PSU
if, by "usb-charger" you were thinking of "power-bank-like" chargers, whilst, in my experience, they can be more stable than the equivalent "wall-wart" devices, the only device I've used and tested showed no observable difference in the loading of its "1A" and "2A" outputs:
http://www.cpmspectrepi.webspace.virgin ... ttery.html

Trev.

[error0x6d]

Ah, ok. I have 512MB RAM and 2 Mounting holes. It looks exactly like this: viewtopic.php?p=209674#p209674

[csagan]

Hello all,
I am attempting something similar to the original poster, I am trying to hook up a Tontec 3.5 inch touch screen and Pi camera module to my RPi2, and was wondering what minimum amps would be suitable for this setup. Have you had any luck with the suggestions given to you thus far? I was looking around different forums finding it difficult to get concrete answers, but it seemed as though 2A was enough for most peoples setups. Thanks!

[kusti8]

Hello all,
I am attempting something similar to the original poster, I am trying to hook up a Tontec 3.5 inch touch screen and Pi camera module to my RPi2, and was wondering what minimum amps would be suitable for this setup. Have you had any luck with the suggestions given to you thus far? I was looking around different forums finding it difficult to get concrete answers, but it seemed as though 2A was enough for most peoples setups. Thanks!

No idea how much current a touchscreen takes, but it shouldn't matter. The Pi takes as much current as it needs, so a 2A power supply, giving some headroom, will be perfect.

[klricks]

Hello all,
I am attempting something similar to the original poster, I am trying to hook up a Tontec 3.5 inch touch screen and Pi camera module to my RPi2, and was wondering what minimum amps would be suitable for this setup. Have you had any luck with the suggestions given to you thus far? I was looking around different forums finding it difficult to get concrete answers, but it seemed as though 2A was enough for most peoples setups. Thanks!

The current into the RPi via the micro USB is limited to 2A by the polyfuse (B+ and 2B models). If you allow the RPi to draw more than that by connecting too many devices, then the RPi will become unstable. So using a 2A supply will assure that the maximum power is available. Using a supply larger than 2A is OK as well but you will gain no advantage. IOW if a 2A supply is not enough for your RPi setup, then you will have to find other ways to power some of the connected devices such as a powered HUB.

[InsideJob]

I use the same Edimax WiFi and a Panda Bluetooth. One amp is almost enough but sadly the red power light flickers when actually using WiFi. So I ended up getting a Tzumi Minimax battery from Walmart for US$20. 1 amp in for charging, 2.1 amps out for my Pi. What's the point of a 3.5" screen if you have to plug into an outlet? I can now stay unplugged for several HOURS while streaming Internet music over WiFi to my Bluetooth headphones.