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dotsdan
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Powering a 5v VFD screen

Fri Mar 27, 2015 1:44 am

Will my RPi have enough power to run a bright VFD on the second 5v port? I am not sure if my RPi will have enough power for a screen. I currently power the it with a usb to serial cable. So, look at the display I found and please let me know what I need for it work.

https://learn.adafruit.com/graphic-128x64-vfd

Have an excelent day,
Daniel

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Forgotten01
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Re: Powering a 5v VFD screen

Fri Mar 27, 2015 1:56 am

Depends.... If you have a B+ or newer, then yes, but you will need to have a good power supply, ideally 2 amp, and you will need to allow the pi to supply more power to it's USB ports via config.txt, you can find out how to do that via a forum search
Engineers like to solve problems. If there are no problems handily available, they will create their own problems.
Scott Adams

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dotsdan
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Joined: Thu Feb 21, 2013 2:50 pm

Re: Powering a 5v VFD screen

Fri Mar 27, 2015 12:07 pm

To add some more info, I have the model B Rev. 1. Here is a link https://www.adafruit.com/product/954 to the cable I use to power it. I have it connected to a usb3 port.

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Forgotten01
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Re: Powering a 5v VFD screen

Fri Mar 27, 2015 6:14 pm

okay, well then you need to have a powered hub, because the B can only supply about 140 mah over it's usb ports, and your screen requires up to 500 mah
Engineers like to solve problems. If there are no problems handily available, they will create their own problems.
Scott Adams

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dotsdan
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Re: Powering a 5v VFD screen

Fri Mar 27, 2015 9:47 pm

Alright, I will look into somthing different then. Thanks.

toxibunny
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Joined: Thu Aug 18, 2011 9:21 pm

Re: Powering a 5v VFD screen

Fri Mar 27, 2015 10:00 pm

I didn't even know vfd was still a thing. What's the advantage of these over oled?
note: I may or may not know what I'm talking about...

Oldsmobile
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Joined: Sun Oct 30, 2016 4:36 pm

Re: Powering a 5v VFD screen

Sun Oct 30, 2016 5:00 pm

The main issues are:

☠ The RPi uses 3.3 V signaling, not the 5 V you normally find in peripherals.
☠ VFDs tend to be quite current-consuming.

The solution I implemented looks like this:

☠ DC-DC converters (so-called level shifters) mapping the 3.3 V RPI signals to 5 V and the 5 V signals coming from the display back to 3.3 V
☠ An add-on board for the RPi named StromPi. This is basically a UPS / stabilizer solution, but also features a USB output which can handle up to 1 A.

And about VFDs themselves: Yes, OLED displays offer almost all of the advantages VFDs also have (high contrast, for instance), but OLED matrix displays are still quite small and might get into trouble in harsh environments.

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