Russian ESR Meter Project: Replacing К157ДА1 with LM358? - Page 1
Forum section: electronics / beginners

author: Savetheday
author_rank: Regular Contributor
timestamp: July 07, 2025, 02:00:10 am
content: Hello everyone,I've found this Russian ESR meter project and I'd like to build it, but the К157ДА1 (K157DA1) component seems to be unique and I can't find it.I understand that the К157ДА1 is a two-channel, full-wave amplitude detector. My question is, would it be possible to redesign parts of the circuit using common Western components like an LM358 (dual operational amplifier) and other basic components such as resistors (e.g., in voltage dividers) to replace the functionality of the К157ДА1? I'm aware that a direct pin-to-pin replacement isn't available.Here's the link to the project:https://radio-hobby.org/modules/news/article.php?storyid=1039And the schematic:https://radio-hobby.org/uploads/schemes2/1039-esr/nm8032_1.gifК157ДА1 Datasheethttps://www.kontest.ru/datasheet/unkn0wn/k157da1.pdfhttps://www.quartz1.com/price/PIC/410N0065316.pdfAny guidance or suggestions would be greatly appreciated!

author: std
author_rank: Contributor
timestamp: July 07, 2025, 04:55:37 am
content: This device estimates capacitor resistance at a certain frequency, called equivalent series resistance, ESR.The result will be an AC voltage proportional to the resistance of the capacitor. On the left is a generator (square waves are not used to measure ESR, but it will work for estimating). Next, an op amp + detector to convert the AC envelope to DC voltage, built using the K157DA1Finally on the right, a modern LED bargraph instead of the old pointer type.The K157DA1 is an Soviet Union original design (all 157 series ICs are original research), so there is no direct pin-to-pin replacement. Today in Russia and former Soviet republics, the only way to get one is to buy it on local second-hand sites. I checked now, prices varies, they sell unsoldered ICs sometimes for absolutely ridiculous prices (500rub ~= $6, but I don't give even $0.5 for it). It's just an op amp at the input and some kind of amplitude envelope detector (i.e. rectifier) ​​after the op amp. The linearity of 157da1 is unknown, the author thinks it's "high precision", but I'm afraid that's just his own opinion, this chip is used mainly in reel-to-reel or cassette tape recorders for level indicators, not such a critical/important application, but with old soviet eelctronic designs sometimes unpredictable amazing things happen.You only need linear AC to DC converter. Everything has been invented before, so check out"The Op-Amp Cookbook". Use the detector circuit from there in place of k157da1. Maybe it's not as simple/beauty as the original K157DA1, but it should work. You need any battery-powered op-amp(s). The LM358 will do.

author: RoGeorge
author_rank: Super Contributor
timestamp: July 07, 2025, 05:22:44 am
content: In case you didn't find that IC:https://www.eevblog.com/forum/projects/5-transistor-esr-meter-design/https://www.eevblog.com/forum/testgear/finding-short-on-motherboards-with-a-shorty-(with-display)/https://youtu.be/bmYAgat-sOQ

author: kripton2035
author_rank: Super Contributor
timestamp: July 07, 2025, 06:12:34 am
content: ...pick another esr meter in my esr meter repository (link below) if you want to have an esr meterif you want to build this for fun, then yeah first try to buy this chip ... good luck.