DC motor speed control with 4049 (PWM)

This DC motor speed control with 4049, is a circuit that allows varying the speed of small DC motors of 3 or 6 Volts that are often found in toys or small electronic devices.

This blown fuse indicator circuit warns us, lighting a LED, when there is a problem in an electrical installation protected by the fuse.

It is very important to correct the faults in the electrical system of an automobile or motorcycle or other, as soon as possible. This circuit will warn us when this happens.

Variable voltage regulator using 7805 and 741.

Very simple variable voltage regulator with very few components. Output Voltage from 5 to 30 volts

Thermistor controlled fan circuit

This circuit varies the speed of a fan connected to a 110 or 220 Volts outlet, using just three transistors and a few additional components.

Electronic Thermostat Circuit using transistors.

This circuit allows us to control the temperature of a room, turning a heating device On and Off. Very useful in winter and in very cold places.

Light Operated Relay Circuit using LDR.

The LDR varies its value (ohms) depending on the amount of light that illuminates it. The more light less resistance and less light more resistance, A potentiometer is used to control the light level that activate the relay

LM350 Adjustable Voltage Regulator (Variable Power Supply)

This variable power supply uses the LM350 adjustable voltage regulator and can deliver 1.25 to 16 volts and a maximum current of 3 amps.

LED Pilot Light Circuit

This Pilot Light Circuit is intended to give us a visual warning that we have electronic equipment turned on. This is especially important on equipment that uses batteries.

High current 555 pulse generator using a voltage regulator

This pulse generator is useful in applications where the pulses given by a 555 alone do not have enough current.

9VDC Power Supply using Zener diode and Transistor

This Power source can be used to power circuits or electronic devices that would normally use a 9 volt battery, saving us the cost of the battery while being used at home.

12v to 24v converter

This 12VDC to 24VDC step up converter is very useful to power devices that run on 24 VDC when we have a 12VDC voltage source as it could be a car battery or alike.

How to Measure Beta of a Transistor? (β / hfe of transistor)

The beta (β) is a characteristic of each transistor. This feature is found in the NTE, ECG manuals, etc. These manuals have a minimum or approximate values of the real values. This means that we do not know the real value of the transistor.