Rongge

This is a simple project of ESR and Low Resistance Test Meter Circuit Diagram. 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, which 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...

If you are doing any electrical work, one of these Non Contact Voltage Test Pens can be quite handy. Just touch the wire that you want to make sure isn’t live and check that the tester doesn’t beep and start flashing. This test pen is on all the time monitoring for AC between 90V and 1000 V. I would have preferred the device to have an on/off switch which would allow the battery to last even longer but I guess they figured that the 1.5 year life that they rate this for when in standby was good enough. This impressive life is because they got the current draw down to under 10 micro amps! Even when operating it only draws a handful of milli amps. [ ]