Path: csiph.com!weretis.net!feeder6.news.weretis.net!news.glorb.com!peer01.iad!feed-me.highwinds-media.com!news.highwinds-media.com!spln!extra.newsguy.com!newsp.newsguy.com!drn From: Winfield Hill Newsgroups: sci.electronics.design Subject: Re: Simple Low Voltage Shut Down Date: 30 Mar 2017 10:20:54 -0700 Organization: Rowland Institute Lines: 50 Message-ID: References: NNTP-Posting-Host: pccc5f3349686db22b4202ab851a43e10c7111d71da4ceaa6.newsdawg.com User-Agent: Direct Read News 5.60 X-Received-Bytes: 1646 X-Received-Body-CRC: 2962017633 Xref: csiph.com sci.electronics.design:454248 Winfield Hill wrote... > >Robert Miller wrote... >> >> I have a little circuit consisting of an LM358 and >> BC547 emitter follower. It runs off 4 x AAA alkaline >> batteries and consumes about 50mA. >> >> What is the simplest way, without consuming additional >> power, of disabling the output from the LM358 when >> the battery voltage drops below around 4V? > >. >. --+-----E C---- >. | B >. 6.2k | ZTX718 >. | 470 >. | | >. | K >. +-----R TL431 >. | A $0.40 >. 10k | >. | | >. --+-------+------ A little hysteresis would be good. . 4.0-volt low-V shutoff. . . ZTX718 . --+-----E C-----+---- . | B | . 6.8k | 120k . | 470 5% hyst . | | | . +------ | -|<|--' . | K . +-----R TL431 . | A $0.40 . 10k | . | | . --+-------+------ Omit the diode, if a little OFF leakage from 127k of resistance can be tolerated. -- Thanks, - Win