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Subject: Re: why does IR circuit oscillate?
User-Agent: slrn/0.9.7.4 (Linux)
Date: 26 Sep 2002 17:25:15 -0600
In article <3D9369B8.B4361D3C@rica.net>, John Popelish wrote:
>> The open circuit output of the IR receiver has a little noise, about a
>> microsecond pulse ever ms or so, but when I connect it to the transistor
>> buffer, it oscillates nonstop. The power to the IR receiver is clean, I don't
>> see any noise on it at all. 'scope was connected with the IR receiver's ground
>> as it's reference.
>The 555 is connected as an oscillator (output fed back to threshold
>and trigger through a resistor to a grounded capacitor). Any time
>reset is not pulled up, the oscillator will run.
I meant at the IR receiver's output. It should be the IR signal with the 40khz
signal removed. When there's an actual IR signal then it looks ok. But when
there's no IR, the receiver's output is noisy as hell, like it is in oscilation.
It's mostly clean when the IR receiver's output is isolated.
>The 10k resistor connected to discharge is also pointless.
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