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From: John Larkin <jjSNIPlarkin@highNONOlandtechnology.com>
Newsgroups: sci.electronics.design
Subject: Re: Another design
Date: Fri, 10 May 2024 11:35:35 -0700
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On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:

>"Edward Rawde" <invalid@invalid.invalid> 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.