100W Power Audio Amplifier
Here the simple and unexpensive 100W power audio amplifier. This circuit should be easy to made.. 
Use this power supply circuit:
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Simple FM Receiver with 1 Transistor
This is very simple FM Radio receiver with only use 1 transistor.
Not only simple and easy to build, this circuit also inexpensive. You can build this circuit with low risk.
LED Flash Circuit
Here the another simple LED Flasher circuit… This circuit uses CMOS 74C04 IC to alternately ON and OFF two LEDs that are connected in parallel.
schematic diagram:
component part list:
Simple LED Flasher circuit
Here the simple LED flasher circuit that you can use for your simple project.
schematic diagram:
component part list:
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10W Audio Amplifier with Bass-boost
This amplifier circuit design is based on the 18 Watt Audio Amplifier, and was developed mainly to satisfy the requests of correspondents unable to locate the TLE2141C chip. It uses the widespread NE5532 Dual IC but, obviously, its power output will be comprised in the 9.5 – 11.5W range, as the supply rails cannot exceed ±18V.
As amplifiers of this kind are frequently used to drive small loudspeaker cabinets, the bass frequency range is rather sacrificed. Therefore a bass-boost control was inserted in the feedback loop of the amplifier, in order to overcome this problem without quality losses. The bass lift curve can reach a maximum of +16.4dB @ 50Hz. In any case, even when the bass control is rotated fully counterclockwise, the amplifier frequency response shows a gentle raising curve: +0.8dB @ 400Hz, +4.7dB @ 100Hz and +6dB @ 50Hz (referred to 1KHz).
High Current Power Supply
This power supply circuit can supply high current for your electronic project. Transistor 2N3055 is the main component which will increase the current level.
| Part | Total Qty. | Description/Value |
| R1 | 1 | 680 Ohm 1/4 Watt Resistor |
| C1 | 1 | 20,000 – 50,000uF 20-40 Volt Capacitor |
| C2, C3 | 2 | 100uF 50 Volt Capacitor |
| C4 | 1 | 0.1uF 50 Volt Capacitor |
| C5 | 1 | 0.01uF 50 Volt Capacitor |
| D1 | 1 | Zener Diode (See Notes) |
| Q1 | 1 | 2N3055 Or Other (See Notes) |
| T1 | 1 | Transformer (See Notes) |
| BR1 | 1 | Bridge Rectifier (See Notes) |
| S1 | 1 | SPST 250 VAC 10 A Switch |
| MISC | 1 | Case, Line Cord, Heatsink For Q1, Binding Posts For Output |
60Watt Power Audio Amplifier
Here the schematic diagram of 60 watts power audio amplifier. The main components is a pair of power transistor 2N3055.
Further information, please visit this page
AC Adapter Reparation Notes
AC adapter basics:
It seems that the world now revolves around AC Adapters or ‘Wall Warts’ as they tend to be called. There are several basic types. Despite the fact that the plugs to the equipment may be identical THESE CAN GENERALLY NOT BE INTERCHANGED. The type (AC or DC), voltage, current capacity, and polarity are all critical to proper operation of the equipment. Use of an improper adapter or even just reverse polarity can permanently damage or destroy the device. Most equipment is protected against stupidity to a greater or lessor degree but don’t count on it. The most common problems are due to failure of the output cable due to flexing at either the adapter or output plug end. See section below on repair procedure.
1. AC Transformer. All wall warts are often called transformers. However, only if the output is stated to be ‘AC’ is the device simply a transformer. These typically put out anywhere from 3 to 20 VAC or more at 50 mA to 3 A or more. The most common range from 6-15 VAC at less than an Amp.
Loudspeaker Repair Notes
Loudspeaker anatomy:
In this document, we use the terms ‘loudspeaker’ or ’speaker system’ to denote a unit consisting of one or more drivers in an acoustic enclosure perhaps along with a frequency selective crossover, tone controls and switches, fuses or circuit breakers. Connections to the amplifier or receiver are via terminals on the rear.
The front is covered with an (optically) opaque or semitransparent grille which provides protection and improves the appearance (depending on your point of view).
A ‘driver’ is the actual unit that converts electrical energy into sound energy. Most drivers use voice coil technology: a very low mass coil wound on a light rigid tube is suspended within a powerful magnetic field and attached to a paper, plastic, or composite cone. The audio signal causes the coil to move back and forth and this motion causes the cone to move which causes the air to move which we perceive as sound.
How to repair and test audio power amplifier
Introduction:
These notes are for audio power amplifiers made from discrete transistors as opposed to those using modules such as the STK series. While many of the concepts illustrated here are useful for smaller power level amplifiers, the large power capacity of some amps need particular techniques. A slight defect that might get by in a small amplifier probably will not in a big one.
Read more the explanation how to repair and test audio power amplifier by downloading this PDF file
