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From: "petrus bitbyter"
Subject: Re: How do I feed 0v/1v logic levels to CMOS?
X-Newsreader: Microsoft Outlook Express 5.50.4807.1700
Date: Sun, 13 Oct 2002 11:33:17 GMT
NNTP-Posting-Date: Sun, 13 Oct 2002 13:33:17 MET DST
Organization: chello broadband
I don't know what current your temperature monitor needs. But the transistor
solution takes 10-20uA from the battery when the output of your device is in
the high state. The input current of a LM339 is in the nA range. When low,
the output current is neglectible for both solutions.
Keep in mind that only a fresh battery delivers 1.5V. Over time this voltage
lowers and the output voltage will lower accordingly.
"Miles" schreef in bericht
> Thanks everyone for your advice, it gets me off to a great start!
> One point I was wondering about is battery power conservation. The temp
> is permanently supplied by a single AA 1.5v battery but draws an
> current. If I feed the 2 outputs (temp too high signal & temp too low
> one of which will probably be high, thru my circuit I don't want to drain
> much current which will reduce battery life. That's why I was considering
> input op-amp like the CA3130E instead of discrete components like
> etc, am I on the right with this assumption?
> Also the circuit am I building will only the on while the PC is on, whilst
> temp monitor will always be on. I read somewhere that's it's not a good
> feed a signal to CMOS without a power supply. Would this be a problem or
> relevant for such a low voltage?
> If anyone is interested I'm building a circuit to control the PC cooling
> monitoring the temp inside the case.
> Thanks again, people.
> On Sat, 12 Oct 2002 12:53:44 +0100, Miles wrote:
> >Can anyone please help me with (I hope) a simple problem.
> >I have a temperature monitoring device with 1.5v battery supply. It
> >logic levels of 0v (low) and 1.5v (high).
> >I want to connect this to a CMOS circuit I'm constructing running of
> >supply (on a PC). The CMOS circuit is a simple logic one using 4001 type
> >transistors etc.
> >I know I need some kind of voltage shifter to up the high level to at
> >or so. I'm considering using single-supply op-amp as a voltage
> >Can anyone suggest a simple way of doing this? Any help, references,
> >would be very much appreciated.
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