Vintage Sensor for ESR tester - II

160

01:16:03

It is easy "vintage" scheme on discrete components. 20 ohm resistor (most left) is  internal resistance of the Capacitor Under Test (ESR tester stimulas: Generic 555 Astable Generator).

The sensitivity and linearity will increase, if we apply the Schottky diodes (or better the old germanium diodes).

Scale of microampermeter is nonlinear as in dc ohmmeter:

ESR    %
0         100
1           91
5           51
10         24
20           8

To compare scales see photo of original ESR-tester (http://ludens.cl/Electron/esr/esr.html). 

published 10 years ago

hurz

10 years ago

You can tune the diode emission coefficient to about 400m to simulate shottky behaviour. Keep it up!

hurz

10 years ago

But why " ... 20 ohm resistor (most left) ... " it must be the 20ohm right to the cap at emitter! The left one is grounded with 5Ohm but this impossible. Guess the descriptions just need update, right? Keep it up.

alexmayorov

10 years ago

Internal resistance of generator is zero (almost). Reactance of Capacitor Under Test is zero (almost too at 50_kHz). ESR of CUT is 20_Ohm (in this example, a bad sample). 20_Ohm and 5_Ohm is voltage divider. Sensor (amplifier) measures the coefficient of division. 5_Ohm is valuable part of this setup.

hurz

10 years ago

But if its the left 20Ohm you can not connect an external 5Ohm between 20Ohm and 10uF. This 20Ohm+10uF is the cap itself !!!

alexmayorov

10 years ago

Vertical 5_Ohm resistor, 10_uF capacitor, right 20_Ohm resistor and all other components is parts of Sensor. To see Component Under Test insert capacitor between pulse source and left horizontal resistor. This capacitor plus resistor of 20_ohm represents CUT. That's all.

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