Ten Myths Adored by Electronics Rookies

Myth 1. A deeper understanding of mathematics is indispensible for the understanding of electrical circuits.

`It is true that proficiency in differentiation and in handling complex numbers is very helpful if not indispensable. However, a beginner or an interested layman will hardly venture in solving two-port matrices or in performing Laplace transforms. The most frequent mathematical operations in linear circuit design are multiplication and division.`

Myth 2. Voltage is the primary electric parameter and voltage gain is the ultimate aim of amplification.

There are two reasons why, in practice, voltage is “more liked” than current. Firstly, voltages occur across electronic components and can therefore be measured easily. Secondly, batteries which are readily available, are natural voltage sources. This preference of voltage is reflected in the fact that operational amplifiers are commonly voltage amplifiers. However, as the amplification of signal power is the aim of any amplifier, current gain is as important as voltage gain, because power is the product of current and voltage.

Myth 3. Amplifiers increase electric power.

`If there were circuits that could amplify electric power no power stations would be needed at all. In any kind of amplifiers power from the power supply is converted into signal power which process is called signal amplification.`

Myth 4. It is important to understand the difference between a dynamic impedance and a static one.

Impedance is the amount of voltage change for a given current change. Voltage or/and current do not recognize how this ratio comes about, i.e., whether this impedance is an intrinsic property of an electric component or whether it arises from the action of some active device.

Myth 5. To realize a properly working electronic system all components must be supplied by the same source. Besides they should be as expensive as affordable.

The signals between electronic devices are not supplier specific but their properties are easily understood so that mixed electronic system can be at least as good as such delivered by one supplier. Increasing the accuracy beyond the need (e.g., using a 1% instrument when measuring a resistance that must be known to 10%) is, in general, a very expensive practice.

Myth 6. Introduction of an electronic component into a loop (e.g., a feedback loop) changes the properties of said component.

It is obvious that a circuit containing a specific component will have properties different from that component. However, an electronic component with properties changing with its use is, probably, irreversibly damaged and should be discarded.

Myth 7. Digital electronics is superior to analog electronics in any respect.

Respect must be paid to digital electronics as far as cost and flexibility is concerned. In general, the response of digital equipment is more difficult to understand compared to analog equipment, partly because the result is less direct. Consequently, digital devices are not the best choice for beginners.

Myth 8. An electronic network should be grounded at as many places as feasible.

Correct grounding is an art that takes a lot of experience. One proper grounding is definitely better than ten arbitrary groundings.

Myth 9. Since the arrival of circuit simulation programs there is no need any more of understanding circuits.

Simulating tools can be a great help for an expert saving lots of time. The amount of knowledge needed to use a simulation program efficiently is certainly greater than a beginner can provide.

Myth 10. In teaching electronics active two-ports should be used from the very beginning because with (passive) one-ports (resistors etc.) you cannot learn anything of importance.

For very good students the method of teaching is quite irrelevant. It seems to be good practice to start any building of knowledge at the fundament.