From:
Newsgroups: sci.electronics.design
Subject: Re: 741 question
Date: Sun, 17 Nov 2002 12:24:26 +0000 (UTC)
Message-ID:
References:
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NNTP-Posting-Date: Sun, 17 Nov 2002 12:24:26 +0000 (UTC)
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carltons wrote:
> In article , "Neil"
> wrote:
>
>> What sort of current consumption can I expect from a 741, configured as a
>> differential temperature switch, running off of a 9volt battery.
>> How long will the battery last in both standby, and when energized, if its
>> output is driving a low-power LED flasher.
>> Is there a lower current consuming equivalent to the 741?.
> If you are worried about battery life, look at the consumption by the
> LED. You can always use a low power op amp with almost no current drain
> driving a bipolar switch to light the LED. BTW, 9v batteries vary all
> over the place for capacity. If you go to a real (as in modern) opamp and
> LED combo, you can probably go to a single Lithium battery and get good
> life.
To go even lower, you could use a switching supply for the LED, to drop the
battery voltage, rather than wasting most of it on a dropper resistor.
A big inductor in series with the LED, a catch diode, and a smoothing cap
would work.
--
http://inquisitor.i.am/ | mailto:inquisitor@i.am | Ian Stirling.
---------------------------+-------------------------+--------------------------
Q: What do you call a train that doesn't stop at stations?
A: Thomas the Bastard. -- Ben