12 Volt Lamp Dimmer - REGULATOR

Here is a 12 volt / 2 amp lamp dimmer that can be used to dim a standard 25 watt automobile brake or backup bulb by controlling the duty cycle of a as table 555 timer oscillator. When the wiper of the potentiometer is at the uppermost position, the capacitor will charge quickly through both 1K resistors and the diode, producing a short positive interval and long negative interval which dims the lamp to near darkness. When the potentiometer wiper is at the lowermost position, the capacitor will charge through both 1K resistors and the 50K potentiometer and discharge through the lower 1K resistor, producing a long positive interval and short negative interval which brightens the lamp to near full intensity. The duty cycle of the 200 Hz square wave can be varied from approximately 5% to 95%. The two circuits below illustrate connecting the lamp to either the positive or negative side of the supply.

12 Volt Lamp Dimmer
Read more »


Read more »

10 - 20Watt Guitar Amplifier


P1______________4K7 Linear Potentiometer
P2_____________10K Log. Potentiometer

R1,R2__________68K 1/4W Resistors
R3____________220K 1/4W Resistor
R4,R6,R11_______4K7 1/4W Resistors
R5_____________27K 1/4W Resistor
Read more »

Wireless IR headphone transmitter

Wireless IR headphone transmitter
Read more »

Wireless IR headphone receiver

Read more »


This circuit will is useful if you have a microphone or a device that produces a low audio level and you want to connect it to a stereo or something. This circuit will boost it's output level.

Read more »


Read more »

P400 hi-fi audio power amplifier

P400 caracteristic
Sinus power:382W (per chanal 8W load impedance)
Load impedance:2-16W
Frecfent caracteristic:5-100000Hz
Frecfent caracteristic:10-40000Hz (-1dB)
Damping factor:>150
Input impedance:60KW
Power supplay:±68V DC
Power consumption:10-450W
Read more »

Mosfet Amplifier - 240W / 400W

Parts List:
Component: Value: Qty:
Resistor 22K, 1W 01
Resistor 18K 02
Resistor 15K 02
Resistor 10K 02
Resistor 4.7K 02
Resistor 22 5W 02
Resistor 470 09
Resistor 220 01
Resistor 100 03
Read more »

12 Volt DC to 120/220 Volt AC Inverter

Low cost 12VDC to 120/220VAC Inverter
This inverter will sufficiently power any of your 115VAC (or 220VAC)small appliances। T1 choice of amperage is yours to make, but if you can salvage a heavy-duty unit from somewhere, use it. The least expensive method to get a larger transformer would be to remove the old 2000v primary and then re-wind an old microwave transformer.
Read more »

PA300 power amplifier (Elektor 11/1995)

Design by A. Riedl

Taken by themselves, the properties of the PA300 amplifier are not revolutionary. But taken in combination, they show something special: a robust 300 watt hi-fi power amplifier that is not too difficult to build.

PA300 power amplifier

There are several starting points to the design of a power amplifier: pure hi-fi without any compromise; simplicity and reliability; high output power. The design of the present amplifier is a mixture of these. The result is a unit that does not use esoteric components, is not too complex, and is fairly easily reproduced. In fact, it could well be named a 'Hi-fi public address amplifier'.
Read more »

MosFet Audio Amplifier 60W into 8 Ohm load

High Quality, powerful unit: 90W into 4 Ohm load

Circuit diagram:
MosFet Audio Amplifier
R1______________47K 1/4W Resistor
R2_______________4K7 1/4W Resistor
R3______________22K 1/4W Resistor
R4_______________1K 1/4W Resistor
R5,R12,R13_____330R 1/4W Resistors
Read more »