1.5 - 35 Volt DC Regulated Power Supply
on Oct 4, 2009 in Power Supply The easy way to power your projectsHere is the circuit diagram of regulated power supply. It is a small power supply that provides a regulated voltage, adjustable between 1.5 and 35 volts at 1 ampere. This circuit is ready to use, you just need to ad...

Low Cost Universal Battery Charger Schematic
on Oct 4, 2009 in Charger Circuits Low cost solution for charging of both NiCd and NiMh batteriesHere is the circuit diagram of a low cost universal charger for NiCD - NiMH batteries. This circuit is Ideal for car use. It has ability to transform a mains adapter in to a charger . This...

Stereo Headphone Amplifier Circuit Schematic
on Sep 28, 2009 in Headphone Amps Portable and small unit, Can be built on a veroboardFirstly, I'd like to stress that the intended use of this circuit is only one of many possible applications. Apart from the obvious usage as a headphone amplifier, the circuit can be used for a rang...

Mains Operated LED Circuit Schematic
on Sep 13, 2009 in Led Circuits Small in size! Big in useHere is a simple and powerful LED circuit that can be operated directly from the AC 100 volt to AC 230 Volts mains supply. The circuit can be used as mains power locator or night lamp etc.. The resistor R1,R2 and capacitor C1...

7 Watt Audio Power Amplifier Circuit Schematic
on Sep 13, 2009 in Amplifier Circuits Small but powerful multipurpose amplifier This small amplifier is constructed around the TDA2003 IC, capable of delivering 4Wrms at 4ohms. The TDA 2003 has improved performance with the same pin configuration as the TDA 2002. The additional features...

AC 220 Volts Flashing Lamps Circuit
on Aug 28, 2009 in Lights Circuits Especially designed for Christmas tree lampsReplaces old thermally-activated switchesThis circuit is intended as a reliable replacement to thermally-activated switches used for Christmas tree lamp-flashing. The device formed by Q1, Q2 and related res...

Fridge Door Alarm Circuit
on Aug 21, 2009 in Alarm Circuits Beeps if you leave open the door over 20 secondsThis circuit, enclosed into a small box, is placed in the fridge near the lamp (if any) or the opening. With the door closed the interior of the fridge is in the dark, the photo resistor R2 presents a h...

Heating System Thermostat Circuit
on Aug 21, 2009 in Alarm Circuits Relay Circuits Security Circuits Controlled by indoor and outdoor temperatureSimple, high reliability designThis circuit is intended to control a heating system or central heating plan, keeping constant indoor temperature in spite of wide range changes in the outdoor one. Two sensor...

DC or AC Voltage Indicator Circuit
on Aug 19, 2009 in Indicator Circuits Detects 1.8 to 230 Volts DC or AC, Minimum parts countingThis circuit is not a novelty, but it proved so useful, simple and cheap that it is worth building. When the positive (Red) probe is connected to a DC positive voltage and the Black probe to t...

Mobile Cellphone Battery Charger Circuit
on Aug 17, 2009 in Charger Circuits Stops charging when battery is full charged, Portable unitCharging of the mobile phone, cellphone battery is a big problem while traveling as power supply source is not generally accessible. If you keep your cellphone switched on continuously, its ba...