This 2 LED Temperature change indicator shows us, by means of two LEDs, when the sensed temperature is above or below a set limit.
When the temperature is above the pre-set temperature level, LED D1 will light up and if it is below, LED D2 will light up.
What is a Zener diode?
The Zener diode is a special type of diode that allows the flow of current on the opposite direction of the arrow of the diode. This diode does not conduct until the applied voltage reaches or is greater of the breakdown voltage. Zener diode is very popular as Voltage reference element.
Tone generator using two 555 timers
This circuit uses the well-known 555 integrated circuit to generate a range of sounds that are heard through a small loudspeaker.
Ohm’s Law relates in one equation the voltage, the current and resistance. Resistance = Resistor’s value.
A more complete expression of Ohm’s Law is achieved using the electric power formula
Water level controller circuit using CD4001
This water level controller circuit controls the level of water in a tank. Unlike mechanical controls using a floating buoy, this circuit uses two sensors, an upper sensor and a lower sensor,
Fuel Pump Cut-off Circuit
Fuel pump cut-off circuit for the car prevents the activation of the pump. Useful to increase the security level of a car which already has an alarm installed
Audio level indicator circuit using LM339
This audio level indicator is very interesting because it allows us to visualize the audio level intensity by connecting this circuit to the input of a loudspeaker.
Rain detector using two transistors
Rain detector using two transistors. Circuit that aims to alert the beginning of the rainfall. Its few components make it an interesting and easy project.
Surge Protection Circuit (Voltage Delay Circuit)
This Surge protection circuit is placed between the DC voltage source and the circuit that you want to power. This circuit delays the voltage given by the power source and allows the voltage to be applied to the circuit or device a few moments later.
Motorcycle Alarm circuit with transistors and relay.
This alarm has, as main elements, 3 transistors, a relay and various sensors, including motion sensors.
Electronic Doorbell Circuit using a 555 timer and a CD4017 decade counter
Electronic Doorbell circuit that lets know that someone is at the door. Made with 555 timer and 4017 decade counter allowing to change the tone of each note
12V Power Supply using Zener and 741 Op. Amp.
This 12V Power Supply has, as its main characteristic, a low output impedance. This is a very desirable feature in voltage sources and is achieved with a large open loop gain that the operational amplifier has.