8/20/2019 Analog ESR Meter

http://slidepdf.com/reader/full/analog-esr-meter 1/5

3/6/2016 Analog ESR-meter  

http://hsahko.mbnet.fi/elek/kv/esr/index.en.shtml 1/5

 Etusivu >Kytkentöjä >E SR-mittari (in finnish)

Analog ESR-meter

This circuit senses the impedance of the capacitor at 100kHz test frequency and converts it to 1V/ohm dcvoltage. So ESR can be sensed with ordinary multimeter. Because electrolytics are mostly resistive at100kHz this voltage is approximately the ESR of the condenser. The measurin range is about 10mΩ...1Ω.

Description:1.Circuit needs stable 12 V and this comes from the 7812.2. 555 genarates 100 kHz square wave. It goes thru the 220Ω current limiting resistor and DC-blockingcapacitor to the test propes.2. Q1 amplifies signal3. Q2 amplifies and filters signal4. Schottky-diode D4 rectifies signal. Trimmer R13 fine adjust sensitivity to 1 V/Ω. Use 0,1 Ω resistor.Procedure: Z ero meter, measure resistor, adjust trimmer, zero meter, measure resistor, adjust trimmer... until

reading of 100mV is achieved

Correct lenght for test leads is 10...20 cm (=5...10 inch). Leads must be bundled together as shown inphoto below.  This is to minimize test lead inductance variation.

Oparating manual:Power onShort test leads. (eg. connect both leads to the same leg of capacitor)Wait until reading is stabile.Select correct range and press the zeroing button on multimeter(REL Δ in meter shown in photo).Meter is ready for measurementZero point shifts if RF-interference level changes eg. you bring meter near compact fluorescent light.

Because of this please check zero point by shorting the leads together and noting the meter shows zero. Pressthe zeroing (REL Δ) button if needed.

Schematic diagram, here 

8/20/2019 Analog ESR Meter

http://slidepdf.com/reader/full/analog-esr-meter 2/5

3/6/2016 Analog ESR-meter  

http://hsahko.mbnet.fi/elek/kv/esr/index.en.shtml 2/5

8/20/2019 Analog ESR Meter

http://slidepdf.com/reader/full/analog-esr-meter 3/5

3/6/2016 Analog ESR-meter  

http://hsahko.mbnet.fi/elek/kv/esr/index.en.shtml 3/5

Improved version with display.You need to add amplifier and zero adjust for the panelmeterSchematic diagram with amplifier  

8/20/2019 Analog ESR Meter

http://slidepdf.com/reader/full/analog-esr-meter 4/5

3/6/2016 Analog ESR-meter  

http://hsahko.mbnet.fi/elek/kv/esr/index.en.shtml 4/5

Meter installed in a box

8/20/2019 Analog ESR Meter

http://slidepdf.com/reader/full/analog-esr-meter 5/5

3/6/2016 Analog ESR-meter  

http://hsahko.mbnet.fi/elek/kv/esr/index.en.shtml 5/5

Printed circuit board. Operational amplifier is TSH22. ACHTUNG! PCB is missing pulldown resistor. Addto IC2B pin 7. About 100 Ω likely works, I used 22Ω one. Or use CMOS op-amp Eagle-files + CAM-data  

Viimeksi päivitetty: 23.07.2011 13:50