ESR & Low Resistance Test Meter


Posted on Feb 6, 2014

As electrolytic capacitors age, their internal resistance, also known as `equivalent series resistance` (ESR), gradually increases. This can eventually lead to equipment failure. Using this design, you can measure the ESR of suspect capacitors as well as other small resistances. Basically, the circuit generates a low-voltage 100kHz test signal, wh


ESR & Low Resistance Test Meter
Click here to download the full size of the above Circuit.

ich is applied to the capacitor via a pair of probes. An op amp then amplifies the voltage dropped across the capacitor`s series resistance and this can be displayed on a standard multimeter. In more detail, inverter IC1d is configured as a 200kHz oscillator. Its output drives a 4027 J-K flipflop, which divides the oscillator signal in half to ensure an equal mark/space ratio. Two elements of a 4066 quad bilateral switch (IC3c & IC3d) are alternately switched on by the complementary outputs of the J-K flipflop. One switch input (pin 11) is connected to +5V, whereas the other (pin 8) is connected to -5V. The outputs (pins 9 & 10) of these two switches are connected together, with the result being a ±5V 100kHz square wave. Series resistance is included to current-limit the signal before it is applied to the capacitor under test via a pair of test probes. Diodes D1 and D2 limit the signal swing and protect the 4066 outputs in case the capacitor is charged. A second pair of leads sense the signal developed across the probe tips. Once again, the signal is limited by diodes (D3 & D4) before begin applied to the remaining two inputs of the 4066 switch (pins 2 & 3 of IC3a & IC3b). These switches direct alternate half cycles to two 1 F capacitors, removing most of the AC component of the signal and providing a simple "sample and hold" mechanism. The 1 F capacitors charge to a DC level that is proportional to the test capacitor`s...




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Pulsed infrared diode circuit
    Simple-ir-detector
    Proximity-switch
    bjt Low voltage/current power supply for wide range of inputs
    49MHz Toy RF Transmitter
    6 x 6 Loop Antenna
    GBluer(Slayer) Exiter



    Top