ELECTRO-DRIVER

 Efficient LED Blinking for Embedded Systems:- Smart hardware design can simplify the embedded software and make it more reliable. Designers use blinking LED signals to indicate different status and for inbuilt testability. Making an LED array blink requires an individual software loop for each LED or an individual timer and specific software to serve it. This can be an issue in a system that uses low-level MCUs which provide limited resources. The circuit presented here solves this problem by adding a simple hardware comprising low-cost inverters with Schmitt trigger for blinking as many LEDs as required. Circuit and working Fig shows the circuit for efficient LED blinking for embedded systems. It uses different arrangements to make five different LEDs (LED1 through LED5) blink at individual rates. The circuit is built around 74HC14 (IC1) containing six inverters with Schmitt triggers at the inputs. The frequency of blinking is usually selected in the 0.2-20...

Simple FM Receiver :- Frequency modulation is used in radio broadcast in the 88-108MHz VHF band. This bandwidth range is marked as FM on the band scales of radio receivers, and the devices that are able to receive such signals are called FM receivers. The FM radio transmitter has a 200kHz wide channel. The maximum audio frequency transmitted in FM is 15 kHz as compared to 4.5 kHz in AM. This allows much larger range of frequencies to be transferred in FM and thus the quality of FM transmission is significantly higher than of AM transmission. Here’s a simple FM receiver with minimum components for local FM reception. Transistor BF495 (T2), together with a 10k resistor (R1), coil L, 22pF variable capacitor (VC), and internal capacitances of transistor BF494 (T1), comprises the Colpitts oscillator. The resonance frequency of this oscillator is set by trimmer VC to the frequency of the transmitting station that we wish to listen. That is, it has to be tuned between 88 ...

This is a simple circuit that activates an alarm when there is a knock on the door or there are any vibrations due to movement of heavy goods or furniture. The circuit uses readily available components.   Circuit and working :- The circuit is built around quad-opamp LM324 (IC1), which is configured in amplifier mode. It uses the piezoelectric element of a piezo buzzer as the input sensor, two transistors BC547 (T1 through T2), a piezo buzzer and some other components for the alarm circuit. Fig. 1 shows the circuit diagram of the door-knock alarm. The reference voltage at pin 3 of IC1 is set by trimming potmeter VR1. The piezoelectric element plate is fixed at the centre of the door using cello tape. Apply a small quantity of adhesive on the edges between the plates. Wires from the piezo element are connected at CON2. These generate an input pulse when vibrations are caused by knocking on the door. The pulse is amplified by op-amp A1 of IC1. Remaining three op...

circuit and working Fig shows the circuit of a simple 12V, 1A SMPS. The circuit is built around a low-power offline switcher TNY266 (IC1), photo-transistor photo-coupler EL817 (IC2), a flyback transformer (X1) and some other easily-available components. Low-power offline switcher (TNY266). The SMPS here has been designed using a TNY266 chip, which is affectionately called the ‘555’ of SMPS. This device has a 700V power MOSFET, an oscillator, a high-voltage switched current source, a current limiting and thermal shutdown circuitry integrated onto a monolithic device. The start-up and operating power is derived directly from the voltage on the drain (pin 5), eliminating the need for a bias winding and associated circuitry. In addition, the device incorporates auto-restart, line under-voltage sense, and frequency jittering. The drain-source breakdown voltage of the MOSFET in TNY266 is important. During the ‘off’ period, the MOSFET sees rectified 317V DC approximately. Addit...