thanks,  yes, the wall wart steps down the mains voltage and convert it to a
DC voltage(unregulated). My microcontroller (M16C/62) is powered via a 7805
regulator. I tried swapping the power supply but the problem still persists.
The problem occurs whenever the power supply made "clicking sounds" which is
during power up and when it's voltage is fluctuating.

btw, I have a rather stupid question: why does the AC-DC power made clicking
sound during startup and when I am tuning the voltage/current up to a
certain value(seems to vary according to the load connected).

thanks alot!

MARK

>From: Dal Wheeler <dwheeler@INSIGHTEK.NET>
>Reply-To: pic microcontroller discussion list <PICLIST@MITVMA.MIT.EDU>
>To: PICLIST@MITVMA.MIT.EDU
>Subject: Re: [EE]:What did the DC power supply done to my event counter?
>Date: Thu, 1 May 2003 12:04:56 -0600
>
>you mentioned a wall wart; to you have a regulator on your controller
>board?
>More details on your power supply might help.
>----- Original Message -----
>From: "Lim KK" <mark_limkk@HOTMAIL.COM>
>To: <PICLIST@MITVMA.MIT.EDU>
>Sent: Wednesday, April 30, 2003 9:12 PM
>Subject: [EE]: What did the DC power supply done to my event counter?
>
>
> > Hi everyone, I've got a  rather weird problem here. I  configured my
> > microcontroller to count incoming pulses using a function called event
> > couter mode. This is commonly used to track the position of a motor
> > movement. The pulse generating circuit and my microcontroller shares the
> > same DC power supply(wall wart). The pulses are sent to the
>microcontroller
> > input pin via a schmidt trigger.
>
>--
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