Using usual diodes instead of Zeners

General discussions about V-USB, our firmware-only implementation of a low speed USB device on Atmel's AVR microcontrollers
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BarsMonster
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Joined: Wed Mar 03, 2010 9:30 pm

Using usual diodes instead of Zeners

Post by BarsMonster » Wed Mar 03, 2010 10:34 pm

Is that possible to use couple of 1N4148 diodes(3.3/0.7 = 4-5 ones) instead of 3.3/3.6V Zener ones?

And sorry for terrible question, can I just feed 5v on a USB as a temporary solution? (I'll have Zeners in about 2 weeks, too slow....)
Will it immidiately burn PC's controller (provided that's a spare PC, and I can sacrafice it :-) )

ulao
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Re: Using usual diodes instead of Zeners

Post by ulao » Thu Mar 04, 2010 12:01 am

I have seen people using 1N4148, and I have powered many projects on another +5 power source.

Grendel
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Re: Using usual diodes instead of Zeners

Post by Grendel » Fri Mar 05, 2010 1:46 am

I would try it without diodes 1st. Supposedly 80% of USB hosts will tolerate it and the ones that don't will just refuse service to the device, not burn up ;)

BarsMonster
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Re: Using usual diodes instead of Zeners

Post by BarsMonster » Fri Mar 05, 2010 1:50 am

Grendel wrote:I would try it without diodes 1st. Supposedly 80% of USB hosts will tolerate it and the ones that don't will just refuse service to the device, not burn up ;)


Thanks for reply.
I think I'll just leave placeholder for zener on PCB, and will just work without them until I would get one :-)
I'll let you know results...

BarsMonster
Posts: 9
Joined: Wed Mar 03, 2010 9:30 pm

Re: Using usual diodes instead of Zeners

Post by BarsMonster » Wed Mar 24, 2010 7:53 am

Ok, finally device works.
It works fine without zenerz and without usual diodes for both 3.3(kinda expected) and 5v supply on both my PCs.

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