Oct 19th, 2009
by Electronics Online.
This is a simple audio mixer circuit diagram:

You can add some resistors in parallel connection for more audio input. To adjust the volume for each input channel, add linear trimmer or potentiometer with configuration: pin1> ground; pin2>output; pin 3>input.
Oct 18th, 2009
by Electronics Online.
Wanna to build an inverter circuit..? This is an ordinary transistorised inverter circuit capable of driving medium loads of the order of 40 to 60 watts using battery of 12V, 15 Ah or higher capacity. This inverter will convert 12V DC input to become 230V AC in output.
Transistors T1 and T2 (BC548) form a 50Hz multivibrator. For obtaining correct frequency, the values of resistors R3 and R4 may have to be changed after testing. The complementary outputs from collectors of transistors T1 and T2 are given to PNP darlington driver stages formed by transistor pairs T3-T4 and T6-T7 (utilising transistors BD140 and 2N6107).
Oct 3rd, 2009
by Electronics Online.

A trimmer or preset is a miniatur adjustable electrical component. It is meant to be ordered aright when installed in whatever device, and never seen or keyed by the device’s user. Trimmers can be potentiometers or varco (variable capacitors – trimmable inductors subsist but are rattling uncommon). They are ordinary in exactitude circuitry similar to A/V components, and may need to be adjusted when the equipment is serviced. Unlike some another variable controls, trimmers are mounted direct on circuit boards, overturned with a small screwdriver and rated for some less adjustments over their lifetime.
Trimmers become in a difference of sizes and levels of precision; for example, multi-turn cut potentiometers exist, in which it takes individual turns of the fitting propellor to accomplish the modify value, allowing for rattling broad degrees of accuracy.
Continue reading
The Trimmers ...
Sep 29th, 2009
by Electronics Online.
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.

Sep 26th, 2009
by Electronics Online.
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.
Continue reading
The Voltage ...