What is ESR Meter?

All capacitors have a definite amount of resistance to the passage of AC current. ESR (Equivalent Series Resistance) is the sum of all internal resistances of a capacitor measured in Ohms. An ideal capacitor has ZERO ohms ESR. From the diagram below you can see a resistor in series with a "PERFECT CAPACITOR". The worth of the resistor is called ESR. Electrolytic Capacitors have an inclination to increase its ESR overtime due to drying or corrosion. High ESR is a frequent issue in today's electronic circuit. Even an ohms rise in ESR may cause complicated issues. Under normal conditions the ESR has a low value, which stays that way for lots of years unless the rubber seal is flawed, in which case the electrolyte's water part gradually dries out & the ESR creeps up with time. The increase in ESR increases both voltage drops within the capacitor & the heat, produced in the capacitors due to resistive heating. In the event you don't check for ESR, you may be in for a "TOUGH DOG" repair. High ESR is the first sign of a capacitor failure. High ESR will cause complete circuit failure, over heating of capacitor, loading of the circuit, overstressing of other circuit parts & other undesirable effects.

Why ought to I use an ESR?

Because measuring an electrolytic capacitor with an analog or digital capacitance meter can MISLEAD a technician in to believing that a defective capacitor is lovely. This can waste your precious time & you are unable to repair the equipment. Which means you cannot charge your customer! In the event you don't check for ESR on the capacitor, you will always miss the bad capacitor. Normally, these bad capacitors have high ESR reading which your normal multimeter or digital capacitance meter cannot measure. Only by using the ESR meter, it is feasible for you to measure the ESR on the capacitor & you won't be fooled by capacitors with bad ESR. ESR meter may even work IN-CIRCUIT, which means you don't must solder out the capacitor in order to measure it using normal capacitor tester, which would not be correct anyway.

Do you know that ESR meters can perform other wonders besides checking the ESR of a capacitor? Some digital ESR meter has the features of checking:

» Low ohms resistor such as 0.22 ohm, 0.33 ohm & etc.

» Horizontal yoke coil winding of a picture tube, inductor & primary winding of a transformer - If a shorted turn is present, the inductance drops dramatically & the meter will show the ohms reading.

» Horizontal output transistor (HOT) in a monitor or TV - If an open-circuit reading is obtained, the short-circuit is elsewhere. If the short-circuit remains, the transistor is flawed.

» Short-circuit in the track, usually trace to the parts - You can use the ESR meter to locate short-circuits on printed circuit boards by measuring the actual track resistance. If the reading increases as you probe further along the track, you know you are going in the wrong direction!

» Speakers, amplifier etc - The pulses have a speedy rise/fall time, so it would probably make a crude RF signal injector as well.

» The condition of both the normal & rechargeable batteries - Flat & defective battery will have high ESR.