This is one of the simplest ways of making an FM receiver. Just get a low cost FM receiver kit, make an audio amplifier using LM386, connect them together and your FM receiver is ready. Most of the commercial FM receiver kits receive the signals within the FM band, usually 88-108 MHz. Read More »
This is a simple 4-in-1 do-it-yourself (DIY) kit from BuildCircuit. The kit has four different circuits that can be switched on separately or together at a time using a DIP switch. The four circuits are: 1. Dark sensor using LDR. 2. A latch circuit using NE555 timer. 3. Astable circuit using NE555 timer. 4. A clap-switch circuit using NE555 timer. Besides these 4 circuits, by changing the values of the resistors and capacitors, you can change the behaviour of the circuits. Read More »
CRYSTAL SET The simplest radio receiver, known as a Crystal Set, consists of nothing more than a coil, tuning capacitor, diode detector, and a pair of earphones. A typical circuit diagram for a Crystal Set Radio is given below where inductor or coil L1 is tuned by variable capacitor VC1 to the transmitter frequency. Diode D1 demodulates the signal, which is fed straight to the earphones. There is no amplification. Read More »
I recommend you to read and understand the basic theory of crystal radio published on this article: http://www.buildcircuit.com/how-to-make-a-batteryless-crystal-set-radio/ Making a batteryless/powerless radio is a great fun, but there are also some difficulties. Read More »
Here’s a simple latch-up circuit using 555 timer and opto-coupler MCT2E. You can also use PC817 in place of MCT2E. The NE555 timer is configured in astable mode.The components are selected in such a way that the frequency output of the astable circuit lies within the audio range. Opto-coupler, MCT2E is is used for latching the alarm.Under normal conditions, pin 4 of NE555 timer is set to ground via resistor R2(470Ohm) and its output at Pin 3 is held LOW. When switch S1 is pressed momentarily, transistor T1 (BC548) conducts to bring reset pin 4 to logic “HIGH” state, as ... Read More »
Just started electronics ? And you don’t know any engineering behind your projects and you are afraid of failure….then just read this article. Usually, success in initial projects plays important role in electronics amateurs and engineering students’ career. Many students quit electronics because they fail in their first, second projects. After few failures, student keep a misconception that electronic projects working today might not work tomorrow. Thus, I recommend beginners to start with those projects which will work in your first attempt and gives inspiration from your own work. Read More »
If you are interested in making a LED lamp with PWM functionality in each LED, you should consider TLC5940. You can get several tutorials about this versatile chip on Arduino. In this tutorial, I am just going to show what kind of outputs you can get with TLC5940. TLC5940 is a 16- channel, constant- current sink LED driver. Using an Arduino and this chip, we can generate up to 16 PWM signals(individually adjustable). The chip can also be daisy chained which offers the possibility of having more than 16 PWM outputs. Read More »
It is a very simple experiment for Arduino amateurs, kids and beginners. It needs two LEDs, one LDR (Light Dependent Resistor), one tactile switch and some resistors of different values. Once the circuit is connected as shown in figure and activated by turning on the switch, it turns on the first LED, according to luminosity of the room. The LED can also be turned with the same switch. Therefore, it works as a toggle switch. Once activated, whenever the LDR senses that the room is dark, it turns on the second LED automatically and vice versa. Read More »
Description: This versatile 741 operational amplifier module can be used for making a dark detector using an LDR, a photo transistor and a photo diode. The amplifier has been configured in inverting mode. It compares the change in voltage at pin 2 with the reference voltage at pin 3 and gives output at pin 6 accordingly. A general calculation and working of similar project has been explained on buildcircuit.com. CLICK HERE for the project. Read More »
Description: The LM386 is an audio amplifier designed for use in low voltage consumer applications. The gain is internally set to 20 to keep external part count low, but the addition of an external resistor and capacitor between pins 1 and 8 will increase the gain to any value from 20 to 200. Read More »
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