diy psu ising a 723 replacement. - Page 1
Forum section: electronics / projects

author: m3vuv
author_rank: Super Contributor
timestamp: August 14, 2021, 11:23:38 am
content: Hi all,i have built variations of this in the past,see attachments,that was with an lm 723,i now have a infinion sg3532 ic to replace it with,i chose it as the cs threshold is 80mv as oposed to 600 with the 723,i plan to use 10x 2n3773 pass transistors driven by a tip 122,also have a range of 50w current sense resistors that i can switch for different ranges,i have a 50v 120.000uf filter cap and a 150amp bridge,can i use the 723 shematic attached to do this,with mods for higher power?,ie sub the 723 with the sg?,just pulling the sd pin low?,cheers in advance.

author: PKTKS
author_rank: Super Contributor
timestamp: August 14, 2021, 11:30:55 am
content: As far as I am aware this is a "clone" of the memorable 723..Itshouldreplace the 723 fine.. although I have ordered not so long ago (circa 6m) a dozen pieces of 723 SMD from AliExpress. They arrived fine working fine...I have I couple of gizmos with 723 since 80s.. remake some in SMD planar format..It should be the same but nothing prevents you from ordering thereal723 ..At least as of today they are still available..There is no replacement for such a master piece..Paul

author: Kleinstein
author_rank: Super Contributor
timestamp: August 14, 2021, 11:41:24 am
content: It is not so much a clone, but an improved version. So it should work in most circuits.The main difference is the current limiting part using a lower voltage and less temperature dependence there. There may be more bias on the surrent sense part. The lower threshold for the current limit can be very convenient at higher currents, using a smaller shunt.

author: m3vuv
author_rank: Super Contributor
timestamp: August 14, 2021, 04:08:36 pm
content: it would be good to say switch between say a cl of say a few ma to tens of amps ,would make it ok for my lion battery builds where current and voltage control are crucial,i sound the 723 lacking in low current limiting/ sensing due to the 600mv threshold.

author: Avelino Sampaio
author_rank: Frequent Contributor
timestamp: August 14, 2021, 04:30:52 pm
content: I recently built a project based on the LM723 , however I used the MAX4080F to have greater control at low currents. I posted it on Diyaudio.https://www.diyaudio.com/forums/power-supplies/368845-functions-mosfet-crc-filter-soft-start-sense-5.html

author: Kleinstein
author_rank: Super Contributor
timestamp: August 14, 2021, 04:33:12 pm
content: The LM723 is made as voltage regulator and the current limit is there for protection. It is not meant to be a lab supply with an adjustable current limit.The 600 mV level for the current limit is more of a problem with high currents (e.g. 10 A) where 500 mV voltage loss at the shunt means a lot of heat.For small currents (e.g. 10 mA) the 500 mV lost are usually not a big deal.For the high current level the SG part makes sense, though I would consider a slightly different circuit, made to get away with less drop.

author: m3vuv
author_rank: Super Contributor
timestamp: August 26, 2021, 01:05:39 pm
content: could you possibly link one,or suggest what to do,i used my 1st one in the schem i posted and somehow killed it! lol,i now have a new one and dont want to kill it,been a project thats been on the shelf for must be a year! tia.