Path: ...!news-out.netnews.com!postmaster.netnews.com!us1.netnews.com!not-for-mail X-Trace: DXC=GdnC9B3lG[nXHfk:;Q?DHgU5[F2hIijDo7J470dMQQ7kJ4R`5ADBYnbCODD059b9ooKOZ<7f X-Complaints-To: support@frugalusenet.com Date: Fri, 10 May 2024 18:20:39 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Another design Newsgroups: sci.electronics.design References: Content-Language: en-US From: bitrex In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Lines: 37 Message-ID: <663e9db7$15$1258340$882e4bbb@reader.netnews.com> NNTP-Posting-Host: 127.0.0.1 X-Trace: 1715379639 reader.netnews.com 1258340 127.0.0.1:39120 Bytes: 2580 On 5/10/2024 5:06 PM, John Larkin wrote: > On Fri, 10 May 2024 11:35:35 -0700, John Larkin > wrote: > >> 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. > > That's overkill. A pfet and one NPN might work. > Speaking of overkill, wrt our previous discussion you might be interested in this mixed-signal array that has 8(!) LDOs on board: