NE555 Monostable

This is a monostable mode circuit of NE555 IC timer. Feature : timing period is 1.1msec, precision, Simple circuitry, independent output duration, 12V supply. Component : Resistor, capacitor, NE555 timer IC. [zen22142.zen.co.uk]

Basic 555 Squarewave Oscillator

The following circuit is a Basic 555 squarewave oscillator. Feature : 1 Khz tone, Simple circuitry, limit = 200 mA, inductive voltage reduced, 4.5-9 Supply voltage. Component : 555 timer IC, resistor, capacitor, Speaker, 2N3053 transistor, push button. [qsl.net]

Bicycle back Safety Light

This is a circuit of bicycle back safety light. Feature : 13 LEDs flashing, 3V supply voltage, Simple circuitry, low voltage, high efficiency, battery powered. Component : Resistor, capacitor, LED, switch, battery, 7555 timer IC. [redcircuits.com]

Four-Hour Timer

The following schematic diagram is four hour timer circuit. Feature : easy to build, 3 hours 53 minutes total time,9V supply voltage. Component : 555 timer IC, Resistor, capacitor, switch, transformer, LED, CD4040B, Relay, BC547 transistor, 1N418 diode, variable resistor. [wiredworld.tripod.com]

DS1621 PC Thermometer Circuit

The following circuit is PC thermometer using DS1621. Feature : plug in any free PC com port, range of -20 to 125°C, Centigrade (°C) of Farenheit (°F) scale, basic accuracy and resolution 0.5°C, readable data log, sampling rate 1, 5, 30 or 60 seconds, basic accuracy and resolution 0.5°C, no external power supply required, easy to build, no calibration required. Component : 1N418 diode, Capacitor, LM2936Z, regulator, DB9 female, Zener diode, DS1621. [riccibitti.com]

CPU Clock Display Circuit

This is a CPU clock display circuit. This circuit shows the CPU speed. Feature : Simple circuitry, easy to build, 5V supply, can display CPU clock. Component : 7 Segment display, Resistor, 1N4001 diode, jumper. [turbokeu.com]

Isolated Full Duplex RS232C Interface Circuit

This is a Isolated Full Duplex RS232C Interface circuit. This circuit is used to protect PC from direct connection to hazardous voltages. Feature : isolate TxD and RxD lines from the PC serial port , baud rate of 19.2k baud, 5V supply. Component : capacitor, 1N4148 diode, LED, DB9, terminal block resistor, 6N137, CNY17-3, 74HC14. [chaokhun.kmitl.ac.th]

Simple Temperature Regulated FAN Speed Controller Using MOSFET

The following circit is Simple temperature regulated FAN speed controller using MOSFET. Feature : + 12 V input voltage, 0-12 V output voltage, nice smooth regulation, noise removed, 47C max load, fan speed was about 3000 as usual.Component : capacitor, resistor, MOSFET P.[www.webx.dk]

Smart Battery Charger Using A Single-Transistor Circuit

The following circit is a smart battery charger using a single transistor. Featre : Simple circuitry, 13.3 VDC supply voltage, single transistor. Component : Battery, resistor, C1061 transistor, 1N4001 diode, relay, capacitor, potentiometer. [electronicdesign.com]

Single Transistor Nicad Battery Charger

This is a nicad battery charger circuit. Feature : Simple circuitry, charge nicad battery, changeable rate, single transistor, charging current 15mA or 45mA,for 1.5V and 9V battery, 12VAC supply voltage. Component : 1N4001 diode, Capacitor, 1N4148 diode, BD140 transistor, switch, resistor,transforme, Fuse.[zen22142.zen.co.uk]

NiCad Discharger for Rx & Tx Packs

This is a NiCad discharger circuit for Rx and Tx Packs. Feature : Simple circuitry, for NiCad battery, Tx battery 8 cell pack,Rx battery 4 cell pack. Component : LM3900 op amp, BD681, LED, resistorm capacitor,7805 voltage regulator, push button, BC548 transistor, Buzzer. [sentex.ca]

Lithium Chargers

This is a lithium charger circuit. Feature : variable current 100mA-2A, simple circuitry, easy to build, inexpensive circuitry, +12V supply voltage. Component : LM741, variable resistor, resistor, zener diode, capacitor, L200. [flyelectric.ukgateway.net]

Motorcycle Battery Charger

The following schematic diagram is a motorcycle battery charger. Feature : 115 or 220V Ac supply voltage, current of 3A, full indicator, simple circuitry, 14.1 volt output. Component : LM350, Transformer, bridge rectifier, capacitor, resistor, potentiometer, 1N4148 diode, BC558 transistor, 1N4001 diode, LED, LM1458. [sentex.ca]

100W Guitar Amplifier Using TL072

This is a guitar amplifier using TL072. This amplifier can amplify up to 100W. Feature : 100W amplification, Simple Circutry, Elegant design, provides excellent tonal range, suit any style of playing, provide a huge amount of gain. Component : Resistor, TL072, Capacitor, Potentiometer, BC549 transistor, Switch, Diode, Zener diodes.[sound.westhost.com]

2.5 W Stereo Class D Audio Power Amplifier Using LM4663

This circuit is a 2.5 W stereo class D audio power amplifier using LM4663. Feature : Two stereo input selector, Micropower shutdown mode, Stereo headphone amplifier, no heatsink needed, “Click and pop” suppression circuitry, Delta-sigma modulator, high efficiency, single supply. Component : resistor, capacitor, LM4663, speaker, headphone.[national.com]

Bench Amplifier

The following circuit is a bench amplifier. Feature : voltage gain of 200, 325mW of power, simple circuitry, work on 4 to 12Volts DC. Component : capacitor, resistor LM386, switch, variable resistor.[zen22142.zen.co.uk]

Balanced microphone preamp

The following circuit is a balanced microphone preamp. Feature : Simple circuitry, inexpensive, 60dB amplification, 12V supply voltage. Component : Resistor, transformer, potentiometer, ne5532, rectifier, 7812, 7912, fuse, capacitor, 7805, zener diode. [nomad.ee]

1 wire Barometer Using MPX4115

This is a 1 wire barometer using MPX4115 circuit. Feature : Simple circuitry, more reliable, output voltage ranges from about 4.17 to 3.72 volts at sea level, about 3.5 to 3.04 volts at 5000 feet, gain of 4.4. Component : MPX4115, 7805 regulator, DS2438, 1N4001 diode, resistor, capacitor, 2N4403 transistor, LM358 op amp, variable resistor. [davidbray.org]

Opto isolated 1-Wire bus

The following schematic diagram is a opto isolated 1 wire bus circuit.
Feature : 1 wire in, 1 wire out, Input is fully 1-Wire compatible, slow rate limited active output, DC/DC converter.
Component : Resistor, transistor, Capacitor, Optocoupler. [home.kpn.nl]

Light Pollution Meter

This is a light pollution meter circuit. Feature : control range of about 2 to 30 microamps, Simple circuitry, easy to build, battery powered, 9V supply voltage. Component : LED, NPN transistor, Digital multimeter, Resistor, potentiometer, toggle switch, battery. [avery.home.mindspring.com]