This in a really simple electronic buzzer circuit based on timer IC NE555. The IC 555 act as astable multivibrator which will generate audio signal frequency. The frequency value is depended the value of 56K resistor and 10nF (0.01 uf) capacitor… you may replace the 56K resistor with a variable resistor to adjust the frequency.
This is the explanation about “Voltage”
Voltage is commonly used as a short name for electrical potential difference. Its corresponding SI unit is the volt (not italicized). Electric potential is a hypothetically measurable physical dimension, and is denoted by the algebraic variable V (italicized )
The voltage between two (electron) positions “A” and “B”, inside a solid electrical conductor (or inside two electrically-connected, solid electrical conductors), is denoted by (VA − VB). This voltage is the electrical driving force that drives a conventional electric current in the direction A to B. Voltage can be directly measured by an “ideal voltmeter”. Well-constructed, correctly used, real voltmeters approximate very well to ideal voltmeters. For non-scientists, an analogy involving the flow of water is sometimes helpful in understanding the concept of voltage (see below).
Precise modern and historic definitions of voltage exist, but (due to the development of the electron theory of metal conduction in the period 1897 to 1933, and to developments in theoretical surface science from about 1910 to about 1950, particularly the theory of local work function) some older definitions are not now regarded as strictly correct. This is because they neglect the existence of “chemical” effects and surface effects. A particular lesson from surface science is that, to get consistency and universality, formal definitions must relate to positions or (better) electron states inside conductors.
This simple amplifier circuit will be nice for newbie project/junior student. Require an IC LM386N to build a mono channel amplifier. There are few components such as capacitor, resistor, potensiometer and speaker in this circuit, so the students will know the real shape of components.
Parts List :
Capacitors : C1, C5 2.2 uF / 50Vecap _________2 C2, C9 10 uF / 25V ecap _________2 C3, C7 100 nF mono (104) ________2 C4 100 uF / 16V ecap ____________1 C6, C8 470 uF / 16V ecap ________2 C10, C11 47 nF mylar (473) ______2 Resistors : R1, R2 10 ohm ___________________2 Pot 1 10k ohm stereo pot ________1 Misc. : IC 1, 2 LM386N __________________2 8 pin IC socket _________________2
The electronic component, Light Dependent Resistor (LDR) or often called photoresistor or cadmium sulfide (CdS) cell is a resistor whose resistance decreases with increasing incident light intensity. It can also be referenced as a photoconductor.
A Light Dependent Resistor (LDR) is made of a high resistance semiconductor. If light falling on the device is of high enough frequency, photons absorbed by the semiconductor give bound electrons enough energy to jump into the conduction band. The resulting free electron (and its hole partner) conduct electricity, thereby lowering resistance.
A LDR device can be either intrinsic or extrinsic. An intrinsic semiconductor has its own charge carriers and is not an efficient semiconductor, e.g. silicon. In intrinsic devices the only available electrons are in the valence band, and hence the photon must have enough energy to excite the electron across the entire bandgap. Extrinsic devices have impurities, also called dopants, added whose ground state energy is closer to the conduction band; since the electrons do not have as far to jump, lower energy photons (i.e., longer wavelengths and lower frequencies) are sufficient to trigger the device. If a sample of silicon has some of its atoms replaced by phosphorus atoms (impurities), there will be extra electrons available for conduction. This is an example of an extrinsic semiconductor.
This article will teach you how to check measure a diode. This is a basic knowledge for students and electronic hobbysts. If your project is failed or your electronic device is broken, then you need to check the components. And before you check the components, you need to learn how to check and measure the components. Here is the explanation about how to check the diode:
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Being able to determine the polarity (cathode versus anode) and basic functionality of a diode is a very important skill for the electronics hobbyist or technician to have. Since we know that a diode is essentially nothing more than a one-way valve for electricity, it makes sense we should be able to verify its one-way nature using a DC (battery-powered) ohmmeter as in Figure below. Connected one way across the diode, the meter should show a very low resistance at (a). Connected the other way across the diode, it should show a very high resistance at (b) (“OL†on some digital meter models).
