Groups > sci.electronics.design > #429948

Re: Input (protection) FET or npn

From	John S <Sophi.2@invalid.org>
Newsgroups	sci.electronics.design
Subject	Re: Input (protection) FET or npn
Date	2016-09-30 12:19 -0500
Organization	A noiseless patient Spider
Message-ID	<nsm6pg$jvp$1@dont-email.me> (permalink)
References	<2ab9c28c-9be2-4569-bf51-56ba6febd9a7@googlegroups.com>

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On 9/30/2016 9:52 AM, George Herold wrote:
> Hi all a simple input circuit take a input pulse. And stretches it a bit.
> (from previous post on pulse stretching.)
> The input looks like this.. (bad asci art)
>
>                  +5V
>                   +--------+
>                   |       R(1M)
>                   _     ---+
>                   ^     |  |
>                   |   |/c  +--->'HC14
> pulse in---R(100)-+---|    |
>                   |   |\e  C(.1u)
>                   _     |  |
>                   ^     GND+
>                   |
>                  GND
>
> 100 ohms in series and diodes to the rails.
> I can then either drive a FET (2n7000) or npn (2n4401)
> both work fine.
> The exact width of the output pulse is not critical.
> Which is more robust?
>
> George H.

What is the nature of the input pulse? 5V, 50V, 500V, etc? Energy 
capability? 1us, 10us, 1000us, etc?

Caution: If the input pulse is very energetic and of sufficient 
voltage/energy, it could raise your 5V rail to device destruction.

Thread

Input (protection) FET or npn George Herold <gherold@teachspin.com> - 2016-09-30 07:52 -0700
  Re: Input (protection) FET or npn George Herold <gherold@teachspin.com> - 2016-09-30 08:05 -0700
    Re: Input (protection) FET or npn Frank Miles <fpm@u.washington.edu> - 2016-09-30 15:28 +0000
      Re: Input (protection) FET or npn George Herold <gherold@teachspin.com> - 2016-09-30 08:52 -0700
  Re: Input (protection) FET or npn John Larkin <jjlarkin@highlandtechnology.com> - 2016-09-30 08:35 -0700
    Re: Input (protection) FET or npn George Herold <gherold@teachspin.com> - 2016-09-30 08:54 -0700
  Re: Input (protection) FET or npn Joerg <news@analogconsultants.com> - 2016-09-30 08:47 -0700
    Re: Input (protection) FET or npn George Herold <gherold@teachspin.com> - 2016-09-30 09:14 -0700
      Re: Input (protection) FET or npn Joerg <news@analogconsultants.com> - 2016-09-30 09:50 -0700
  Re: Input (protection) FET or npn John S <Sophi.2@invalid.org> - 2016-09-30 12:19 -0500
    Re: Input (protection) FET or npn George Herold <gherold@teachspin.com> - 2016-09-30 11:40 -0700
      Re: Input (protection) FET or npn Joerg <news@analogconsultants.com> - 2016-09-30 12:38 -0700
      Re: Input (protection) FET or npn John Larkin <jjlarkin@highlandtechnology.com> - 2016-09-30 13:15 -0700

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