Path: ...!Xl.tags.giganews.com!local-2.nntp.ord.giganews.com!nntp.supernews.com!news.supernews.com.POSTED!not-for-mail NNTP-Posting-Date: Fri, 10 May 2024 18:37:23 +0000 From: John Larkin Newsgroups: sci.electronics.design Subject: Re: Another design Date: Fri, 10 May 2024 11:35:35 -0700 Organization: Highland Tech Reply-To: xx@yy.com Message-ID: References: X-Newsreader: Forte Agent 3.1/32.783 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 26 X-Trace: sv3-t3tOID+9PymmBD1yFgaztYZby2EPLHhuZpPFGoPQeI3MStRGOAXeUOO0MLNxfFLa+3EqdOa4imfPhlL!kQw9rI9WXsTXqKKIhGFdNbfzXH7a4Nz3u38sisOLWR95zs1xKey54ZfHtPQ7kIH50tdf9zO5oVmV!mZh9qA== X-Complaints-To: www.supernews.com/docs/abuse.html X-DMCA-Complaints-To: www.supernews.com/docs/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 Bytes: 2089 On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde" wrote: >"Edward Rawde" wrote in message >news:v1ho21$4ps$1@nnrp.usenet.blueworldhosting.com... >> Now with 9V to 15V input range, direct gate drive and 500mA LED current. >> >> Startup behaviour is not ideal but maybe that can be fixed if it needs >> fixing. >> >> What's the cheapest op amp I can use for U2 instead of OP07? >> >> Is there a cheaper comparator instead of LT1719 which will work? >> Also the fet is bigger than it needs to ne. >> >> Is there a better device for D4? Particularly if R4 can be reduced. >> >> Will it work at all? Except in simulation. >> > >I think I've answered my own question for the current controller but I don't >think it's feasible to attempt a discrete comparator on cost grounds. I think the LED constant-current switcher can be done with a pfet and two NPN transistors.