Digital thermometer circuit. CA3162, CA3161 & LM35. A simple digital thermometer circuit with out a micro controller and having a seven segment LED read out is shown here. The circuit is based on three ICs: CA3162, CA3161 and LM35. CA3162 is a monolithic analogue to digital (A/D) converter that has BCD output. The A/D converter […]
Water level controller circuit Note:- We have developed another water level controller circuit using micro controller AT89S51 from Atmel. If you are interested, read that too :- Water level controller using micro controller Are you familiar with the basics and the different applications of the 555 timer IC. If not, we recommend you 3 books
Description. Here is the schematic of a very simple electronic thermostat using IC LM56. LM56 is a very accurate dual output low power thermostat from National Semiconductors.LM56 has various useful features like internal temperature sensor, two internal voltage comparators, internal voltage reference etc. Two stable temperature trip points (VT1 and VT2) are created by dividing
Description. Just about any power transistor can be used in this megaphone.Its suitable for boats,playing fields etc.the transistors Q1 & Q2 are the HEP-230 type which are easily available in the market.The transistors are parallely connected to handle the required power and speaker matching.The microphone is a carbon type like that used in telephone hand
Description. This is a compact electronic siren circuit based on three transistors.This circuit is suitable for in corporating with other alarm or siren projects such as burglar alarms, automatic factory sirens etc or a simple push to on alarm. The electronic siren circuit given here  is based on a complementary transistor pair consisting of Q2
Description. This circuit can give a visual indication of the rate of air flow.It can be also used to check whether there is air flow in a given space. The filament of a incandescent bulb is the sensing part of the circuit.When there is no air flow the resistance of the filament will be low.When
Description. Here is the circuit diagram of a magnetic proximity switch that finds a lot of applications in many fields.The circuit is based on a magnetic reed switch(S1) as the proximity sensor. A monostable multivibrator based on NE555 (IC1) and a toggle flip flop based on CD4013 (IC2) does the rest of the circuit. When
Description. Here is a simple circuit that can be used to switch ON or OFF a device when the dew present in the surrounding atmosphere crosses a set value. The circuit uses a dew sensitive resistive element and a comparator based on LM 358 to perform the above said operation. At normal condition the resistance
Description. A variety of humidity tester circuits are available, but this is a circuit which is as simple as possible. Using only a transistor, LED and few resistors, this circuit can be used to check the humidity level of materials like soil, paper etc. When the humidity in a substance increases the current conducted throughÂ
Description. Here is a straight forward, yet effective digital temperature controller that can be used with temperature control systems. The circuit uses IC LM 35 (IC3) to as the temperature sensor. The output of LM 35 is given to the IC ADC 0804 (IC4) which converts the analog output of the LM 35 to digital
Description. When there is a fire breakout in the room the temperature increases. This ultra compact and low cost fire alarm senses fire breakout based on this fact. Transistor BC177 (Q1) is used as the fire sensor here. When the temperature increases the leakage current of this transistor also increases. The circuit is designed so
In this guide, we are designing a Liquid Level Switch using 3 transistors (BC107), some passive components, a diode and a couple of relays. This is basically a level sensing circuit designed using minimal components. If you’re looking for an efficient level sensing circuit, you would be better off with our water level controller circuit.
In this project guide, we’re building a Touch Switch Circuit using NE 555 IC. As you know, NE/SE 555 is a very popular timer IC with multiple applications in different projects. A touch switch is basically a simple switching circuit activated upon a touch. If you’re new to 555 IC, please take the time to
In this project, We’re building a Photo Switch Circuit using 555 IC. If you’re not familiar with the term ‘photo switch’ – this is nothing but a light-activated switch. The switch will turn ON/OFF based on light intensity. We’ve designed this photo switch circuit using simple & popular components. The heart of this circuit is
InfraRed (IR) Sensor/Detector Circuit The IR circuit described below is mainly designed for liquid level detection or proximity detection. The IR sensors used here are an IR LED and an IR photo diode. The circuit operates by detecting the distance from the target by reflection of an infrared beam. The biggest advantage of this circuit is
