sl technological sevices

GSM modules   are fascinating to use especially when our project requires remote access. These modules could make all actions that our normal mobile phone could do, like making/receiving a call, sending/receiving a SMS, connecting to internet using GPRS etc. You can also connect a normal microphone and speaker to this module and converse on your mobile calls. This will open doors to lot of creative projects if it could be interfaced with a Microcontroller. Hence in this tutorial we will learn how we can   Interface the GSM module (SIM900A) with our PIC microcontroller   and will demonstrate it by making and receiving call using GSM Module.  We have previously interfaced it with Arduino and Raspberry Pi for calling and messaging. Materials Required: PIC Microcontroller (PIC16F877A) GSM module (SIM900 or any other) Connecting wires 12V Adapter PicKit 3 The GSM module: The GSM module can be used even without any microcontroller by using the AT command mod...

An active crossover circuit will certainly produce better sound quality than the passive type, the LM741 IC used in the audio circuit this time is quite easy to get to be used as a crossover that will be forwarded to the power amplifier. Crossover on the amplifier, there are two types of crossover that is, active crossover and passive crossover. Each crossover has advantages and disadvantages depending on the needs of each. While on the crossover circuit that I share here is an active crossover circuit using IC LM741 which is none other than single op-amp IC. Active crossovers will certainly provide better quality for your Hi-fi system that intends to upgrade the sound quality. The workings of this active crossover simply by breaking the audio input signal into 4 bands, low frequency, medium frequency, high frequency and subwoofer frequency. The circuit can be activated using double supply +15 / -15 V DC.Below the schematic diagram of active crossover circuit. ...

Attendance systems are commonly used systems to mark the presence in offices and schools. From   manually marking the attendance in attendance registers to using high-tech applications and biometric systems, these systems have improved significantly. In our previous projects, we have covered few other electronic attendance system projects using RFID and AVR microcontroller, 8051 and raspberry Pi. In this project, we used fingerprint Module and Arduino to take and keep attendance data and records. By using fingerprint sensor, the system will become more secure for the users. Following sections explains technical details of making a fingerprint based biometric attendance system using Arduino. REQUIRED COMPONENTS Arduino -1 Finger print module -1 Push Button     - 4 LEDs -1 1K Resistor -2 2.2K resistor -1 Power Connecting wires Box Buzzer -1 16x2 LCD -1 Bread Board -1 RTC Module -1 PROJECT DESCRIPTION: In this fingerprint attendance s...