Electronics FAQ – Your Multilingual Guide to Electronics

  Purpose of Dual Power Supply in Analogue Circuit Design: Why Positive and Negative Voltages Matter Look at the following two circuits… A Push-Pull audio single-ended Amplifier:     Push-Pull Audio Amplifier with dual Power Supply: What is the difference between the two above circuits? In the second circuit, there is an absence of an output coupling capacitor. Why is a capacitor needed in the first circuit? It charges at a positive cycle and discharges at a negative cycle, generating an AC voltage across the speaker. In the second circuit, at the positive input cycle, current flows to the speaker. At a negative input cycle, current is pulled from the negative supply through the speaker, thus eliminating the output capacitor. The output coupling capacitor has a few disadvantages. It puts a limit on low-frequency response, it is bulky, and needs a high value for better low-frequency response; it may dry out, and needs a replacement after a certain period. Conclusion: ...

 Time delay in the voltage stabiliser: purpose, benefits and explanation Some AC voltage stabilisers, especially recommended for refrigerators, have an inbuilt time delay function that delays output switching when it is turned ON or after a power failure. This post explains the real purpose of it.  The real reason is compressor lockup: Suppose the running compressor (e.g. refrigerator) is interrupted by a short-term (momentary) power outage (less than 10 seconds). In that case, the compressor locks up, the motor draws heavy current, and the compressor becomes hot. There is over-temperature protection for the compressor that trips the compressor. Powering on the delay of the voltage stabiliser solves this problem. If the running compressor is interrupted by a short-term power outage, the power-on delay does not power the compressor until the time delay is complete. This gives sufficient relief time for the compressor to come out of the vapour lock stage. FAQ: Time Delay in Volt...

Voltage Regulator vs Current Regulator: Definition, Working Principle, Circuit, and Key Differences in Electronics A word ‘regulator’ means control, similar to the gas flow control in our home gas stove. That way, the word ‘voltage/current regulator’ is a bit of a misnomer. The correct wording is ‘Automatic Voltage/Current Regulator’. However, I will use the word' voltage regulator in place of ‘Automatic voltage regulator’ in the following answer. Voltage/Current regulator definition:  Voltage/Current regulator keeps the voltage/current level at the predetermined level within a narrow tolerance band with respect to the input and load variations. Coming back to the OP’s question, the following is the feedback control diagram of the regulator. Voltage regulator block diagram: The principle of operation is very simple. The sampled output voltage is compared with the reference voltage set by the zener diode. Any error is nullified by a control element, which absorbs the differace in vo...

Electrical Earthing Tests – Importance, Types, Procedures, Safety Standards, and Best Practices Explained. Easy method to test home earthing. An instrument that measures ground (earth) resistance: If you're paranoid about the effectiveness of the earthing, then you need three three-wire earthing tester. There is a procedure for that. You may also call a third-party agency that certifies electrical earthing. But, is there an easy, inexpensive method? Yes. It is crude, but it gets the job done. Method-1 (Using filament lamp) Take a 100W filament bulb with a holder. First test it across the phase and neutral of the home electrical plug. Note the brightness. Then connect the bulb to the Earth and the Phase of the plug. Note the brightness. If the electrical earthing is good, you will have equal brightness in both cases. Why bulb lights with Earth-Phase connection? I have explained it   here. Method-2 (Using Digital Multimeter) You need a DMM.   Measure the voltage difference betwe...

How Does a Capacitor Work as a Voltage Regulator? Working Principle, Applications, and Circuit Examples of how capacitors stabilise the voltage level What is a voltage regulator? Voltage regulator’ is not a very appropriate word, although a capacitor does improve voltage regulation. A regulator is an (electronic) arrangement that maintains the output voltage within a predetermined narrow voltage tolerance band against input voltage fluctuations and load variations. ‘Stabilise the voltage level’ is what a capacitor does by bridging the gaps between the demand and supply of the load current. AC to DC conversion:  How capacitor regulate DC voltage? A capacitor charges to the peak of the incoming voltage level and tries to maintain it by supplying current to the load through self-discharge. FAQ Set: Q1: How can a capacitor regulate voltage? A capacitor regulates voltage by storing and releasing electrical energy, smoothing out fluctuations in DC voltage and providing a more stable outp...

How does a capacitor smoothens a voltage and how does an Inductor smoothen the current Take a large reservoir of water. Does the inlet of water increase the water level suddenly? No. Watertank analogy of a capacitor: Does the outlet of water suddenly decrease the water level? No. A capacitor is like a water tank. Inlet water is like a charging current. The outlet of water is like a discharge current. Water level is like the voltage of a capacitor. DC ripple filter: The process of how a capacitor maintains its voltage level is best explained by how a filter capacitor smoothens the DC ripple. When the incoming voltage increases, it charges to that voltage. When the incoming voltage decreases, it uses its stored energy to supply current to the load by maintaining the voltage level. As long as demand le less than supply, it comfortably maintains almost a constant level of voltage across the load. That is exactly what an overhead water tank in our home does when there is an irregular water ...