> -----Original Message-----
> From: Jan-Erik Soderholm [SMTP:jan-erik.soderholm@telia.com]
> Sent: Sunday, November 17, 2002 11:29 PM
> To:   PICLIST@mitvma.mit.edu
> Subject:      [EE]: PSU, 9805 and a diod.
>
> Only resent with a correct subject...
> Sorry, Jan-Erik.
>
>
> Hi.
> A simple question...
>
> I have an old PSU (have been feeding a Intermec barcode scanner) with
> +5, +12 and -12 volts.
>
> Now, I noted that the +5 volt actualy is closer to +5.8 volts.
>
> I opened the box and it's a simple 9805 (well two in paralell actualy)
> that have the "central" pin connected to ground via a simple 4148 diod
> with the cathod to ground. Would this give the extra 0.8 volts on the
> output ?
>
> Can I simply short the diod to lower it to aprox 5 volts ?
> Or could this have something to do with the fact that there is
> *two* 9805 connected together (pin 1-1, 2-2 and 3-3) ?
>
Putting diodes in the common leg is a popular way to increase the voltage of
these fixed voltage regulators, and this would explain the voltage increase.
The two parallel devices is no doubt an attempt to double the output current
capability, although it's not really the recomended technique.

Mike

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