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Author Topic: Arduino Ferrite Bead?  (Read 2443 times)
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Hi,
I'm approaching my dream: to assemble DIY Arduino wow!

I'm working on Arduino Duemilanove information here:
http://arduino.cc/en/Main/ArduinoBoardDuemilanove

Some questions remain I hope somebody point me to right tutorial/information:



1. For the FT232RL, a Ferrite Bead is used on schematic, which is marked F1 and valued: 500mA. I want to order it from local electronic component store, but they need more parameters. On the datasheet of FT232RL I also failed to find complete parameters (may be for this is a known filter everybody other than me knows about!). Also, I checked on my original Arduino board, and I see a golden part on which it is written "507S" (if my eyes are not tricking me). Could anyone please let me know what exactly I have to tell to the local seller so in response to receive this 507S Ferrite Bead please? smiley

2. There is an electronic symbol new to me on the schematic. I guess it is a jumper place which is simply left as two unconnected wholes on the board. Am I right please? I provided its image in this post called "what_is_this.TIF" as i didn't know how to call it at all!

3. Locally, I can't find the part "NDT2955" which switches between power sources, is there any alternative part(s) I can choose from?

Thanks in advance for help!
 smiley


* what_is_this.TIF (5.47 KB, 189x161 - viewed 122 times.)
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I can't help you with 1 and 3, but for 2:
http://www.rapidtables.com/electric/Solder_Bridge.htm

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That item is not "Ferrite Bead", is SMD Poly Fuse.
http://en.wikipedia.org/wiki/Resettable_fuse
http://parts.digikey.com/1/parts-kws/smd-poly-fuse
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I can't help you with 1 and 3, but for 2:
http://www.rapidtables.com/electric/Solder_Bridge.htm



Thanks Carmatic, question cleared smiley
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Thanks BillHo, I'm still confused, please see the attachments, I can't know understand:
1. on schematic I (think) I see the Ferrite bead of 500mA because the same thing is on datasheet of FT232RL,
2. on board as you pointed, there is a fuse,

What is it going on there? the fuse is working as a filter?! where gone the inductor then?

Thanks


* is_this_inductor_or_fuse.TIF (111.68 KB, 570x229 - viewed 100 times.)
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A ferrite bead is a good idea but not absolutely necessary. A fuse is also optional but will protect your computer's USB port. I think this is just a design decision that the designer made.
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A ferrite bead is a good idea but not absolutely necessary. A fuse is also optional but will protect your computer's USB port. I think this is just a design decision that the designer made.

you mean to use a fuse and not to use the ferrite bead right? so as an option one can choose between them?
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Yes, use both if you want.
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The FTDI specs recommend the ferrite bead, but none of the Arduinos has ever included it.
The part labeled F1 in the schematic is indeed a fuse (self-resetting polyfuse.)

The NTC and Solarbotics "Freeduino" board designs got a bit more paranoid about following the FTDI recommendations, and include both the fuse AND the ferrite bead.

The fuse and the ferrite bead preform different functions; the ferrite bead is for noise suppression on the USB cable (which you might not notice, even if it happens), while the fuse prevents dangerous currents from flowing in the event that an Arduino user accidentally shorts the power rails while the Arduino is connected to a PC with a big power supply and not enough protection on the USB port (this SHOULDN'T happen; the PC side is supposed to be protected as well, and many PCs have a very similar fuse on the other side of the cable.  But there were actual reports of users managing to reset their PCs with a badly placed wire on their arduino setup.)

Neither is required all the time.  I built my freeduino prototypes with pieces of wire where both the fuse and the ferrite bead were supposed to go, and I'll probably continue to do so.

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The FTDI specs recommend the ferrite bead, but none of the Arduinos has ever included it.
The part labeled F1 in the schematic is indeed a fuse (self-resetting polyfuse.)
........

Thanks a lot all !

I've got answer more than complete smiley-grin
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I have two NDT2955 and i can send to you if you paid the shipping ,i live in spain
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I have two NDT2955 and i can send to you if you paid the shipping ,i live in spain

Many thanks for the offer! could you plz private message me your email so I contact you?
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