Sheesh.

How can that work?

Mark

Spehro Pefhany wrote:
> At 12:39 PM 12/03/2010, you wrote:
>   
>> Hi, List.
>>
>> I am working on a mixed signal system and I need to generate a smallish
>> negative voltage, (say -1V or so) for use as a negative op
>> amp/comparator supply to overcome problems like comparators not swinging
>> to ground, etc.
>>
>> In the past, I have used ICL7660's or National LM2687, both work well;
>> solid enough and quiet enough, but they seem like overkill....does
>> anybody have a favorite, simple solution for something like this?
>>     
>
> Not exactly practical in most cases (not much output current available,
> requires high input voltage & power), but there's this simple & cheap one:
>
>
>                +12VDC              eg. 2N4401
>                   +       E    C
>                   |  ___
>                    -|___|- -   -  output (-300 ~ -400mV)
>                             ^ /
>                      1K     ---
>                              |
>                              |
>                             ===
>                             GND
>
>
> Don't bother trying to SPICE it.
>
> Best regards,
>
> Spehro Pefhany --"it's the network..."            "The Journey is the reward"
> speff@interlog.com             Info for manufacturers: http://www.trexon.com
> Embedded software/hardware/analog  Info for designers:  http://www.speff.com
>
>
>
>   
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