Electronics Engineering

The time constant of a 4.7 µF capacitor in series with a 22 KΩ resistor is about 103 ms.

2000 centigrade degree

transistor has 2 output 1 and 0 so can be used as a switch

The dynamic resistance of a diode, be it zener or otherwise, will be different from its static resistance because a diode is not a resistor, and resistance is not a function of current flow. It is a diode, and a diode has its own characteristic voltage to current curve, forward and, in the case of a zener, reverse.

to increase the sensitivity for the same damping torque

no

the flow in the semiconducoter is because of flow of elecrons and holes.because electrons and holes are diffused into each other in the forword baised

in bc107 transistor b stands for the material i.e,silicon here and c stands for af low power signal

The hFe (current gain) on the BC148 ranges from a minimum value of 20 to 100, depending on collector current, with a maximum value of 300.

The 74LS00 is a quad two input NAND gate with low power schottkey TTL implementation.

Optical Reader

When designing a transformer you have to calculate the number of primary windings so that the transformer will operate properly/efficiently. There are a few different variables that have to be taken into account.

Ac:

Ac is the effective cross sectional core area. This number should be supplied by the core manufacturer.

B:

Flux density (B) is expressed in gauss. If the flux density is too high the core will saturate (effectively disappear from the magnetic circuit - very bad). Generally, in car audio amplifier switching power supplies operating at or below 35.000hz, the flux density is kept at or below 2000 gauss. Some cores will operate at higher flux density for frequencies below 35,000hz but 2000 gauss is a good conservative number. For higher frequencies, you have to design for lower flux density to prevent excess core heating. For a more precise value for a given core material, refer to the core manufacturer.

Primary Voltage:

The primary voltage for a push-pull system is double the primary input voltage. For car amplifier switching power supplies, the input voltage is 12VDC. This means that the total primary voltage is 24 volts. If we use 13.5 volts as the input voltage, the primary voltage would be 27 volts.

Operating Frequency:

The operating (oscillation) frequency is simply the frequency at which the primary is driven. Generally between 25,000hz and 50,000hz in car audio amplifiers.

Primary Turns:

The number of primary turns returned by the calculator is the total number of turns on the primary side of the transformer. Of course, with a push pull system, the number of turns on each half of the primary must be equal. If the output says that you need 13 turns, you'd round up to 14 turns and each half of the primary would have 7 turns. From the previous diagram, you'd have 7 orange turns and 7 green turns on the core.

Skin Effect:

When wire (specifically, solid copper conductors as are used for transformers) is used to carry DC current, the entire cross sectional area of copper carries the current equally. When wire is used for AC current, the current is carried differently. At low frequencies, the current flow is not significantly affected by the skin effect. As you get into the higher frequencies (as those used to drive a transformer in a switch mode power supply), the current flow is carried disproportionately by the outer area of the copper wire (especially for large single solid conductors). This is called the skin effect. If, for example, you are using 14g wire at 100khz, the wire will not be able to carry the same amount of current as it could if it were passing DC. If your calculations told you that you needed to have ~4120 circular mils, you'd have a few choices. You could use 1 strand of 14g wire, 3 strands of 17g or 6 strands of 20g. All would have the same current carrying capacity if you were using it in a DC circuit but... If you were using it for AC, the 14g would only be suitable for frequencies below ~6000hz. Above that frequency, the voltage losses and power dissipation may be unacceptable (it would still work above 6000hz but not efficiently). The maximum frequency that you'd want to use with the 17g would be about 11,000hz. For 22,000hz the 6 strands of 20g would be a good choice.

it gives a nice pleasurable experience

It can hold a very large amount of charge and release the same over along period of time.

It depends in what circuit you are using it.

For power supply decoupling and regulation, bigger is better.

If you change the capactior value in a timing or tuned circuit, it will not behave as designed.

Yes. Setup the 555 as an oscillator and plug the capacitor under test into it and measure the frequency of the signal generated. For more precision, measure the charge time only, and use a constant current source, but that is getting more complicated than need be - there are far better ways to test a capacitor than with a 555.

if channel width decreases , the drain current(Id) will also decrease .

but , Id will decrease up to a certain limit , when the jfet is in pinch off condition i.e. channel width is tends to zero (Vgs is very high) the Id will be constant then.

A tap changer is used to vary the turns ration between the windings of a transformer to make minor changes to the secondary voltage. An on-load tap changer enables the turns ratio to be altered without disconnecting the transformer. An off-load tap changer requires the transformer to be temporarily diconnected. On-load tap changers are installed on the high-voltage side of the transformer, where the current is lower.

sadasx

its nothing but alternate occurence of pole/zero and zero/pole. ex: f(s)=s*(s+2)/(s+1). here we can easily sense that there is a occurence of zero(s=0),pole(s=-1),zero(s=-2).

It can be answered in two ways :

1. ratio of output & input voltages [Vout / Vin] i.e Drain voltage(Vds)/Source voltage(Vs).

2. multiplication of trans-conductance & drain resistance .