Ocean College and School Students Science Projects materials

In this article we explain how to do PWM (Pulse Width Modulation) control using arduino. If you are new to electronics, we have a detailed article explaining pulse width modulation. We have explained PWM in this tutorial using 2 examples which will help you learn how to control LED brightness using PWM and how to control DC motor speed using PWM. PWM control using arduino. PWM control is a very commonly used method for controlling the power across loads. This method is very easy to implement and has high efficiency. PWM signal is essentially a high frequency square wave (…

This article is a compilation of the simple and popular audio circuits we have published over years in CircuitsToday. This list involves a collection of simple amplifier circuits that you can try at home and some other audio related circuits with specific applications. Image Source 1. 150 Watt amplifier circuit – This circuit is the most popular amplifier we have ever published. It has received over 700+ comments and is still counting. This amplifier has been tested by many readers of CircuitsToday and many of them got correct output. Most of the problems and troubles raised by readers while testing…

ICL 8038 waveform generator. ICL8038 is a monolithic waveform generator IC that can produce sine, square and triangular waveforms with very little distortion. The frequency can be programmed from 0.001Hz to 300 KHz using external timing capacitor and resistor. Frequency modulation and sweeping can be attained by using an external voltage. Other features of the ICL8038 are high linearity, high level outputs, simultaneous sine, square, triangle wave outputs, low external parts count, high temperature stability etc. The working of ICL8038 is as follows. The external timing capacitor (C2 in the circuit diagram) is charged and discharged using two internal current…

Class D amplifier. Class D amplifier is a type of amplifier where the power devices (MOSFET or transistor) are operated as switches. There will be only two states (ON/OFF) for these switches and no time is wasted for the transition from one stage to another. The working of a class D amplifier is as follows. At first the audio signal to be amplified compared with a high frequency triangle waveform and the result will be a square wave whose duty cycle is proportional to the input audio level. This square wave is then fed to the gate of the switching…

LA3161 Stereo Preamplifier. LA3161 is an integrated 2 channel pre-amplifier intended for car stereo applications. The LA3161 has a built in voltage regulator which plays a great role in improving ripple rejection . The IC requires minimum number of external parts and the noise level is very low. The IC has high input impedance (around 100K) and is available in an 8 pin SIL package. Description. In the circuit both of the built in amplifier section are used. Capacitors C8 and C9 are input coupling capacitors. Capacitors C3 & C6 are noise filter capacitors. The lower cut-off frequency depends on…

Digital volume control circuit. MAX5486. A two channel digital volume control circuit based on IC MAX5486 is shown here. MAX5486 is a 40K dual digital volume / balance controller that has a pushbutton interface. The IC has a built in bias voltage source that eliminated the need of an external circuitry for the same purpose and thereby by reduces external parts count. The IC also has an LED status indicator driver circuit which can be used for driving the status indicator LEDs which indicates the volume level and balance level. The IC can be operated from a single or dual…

100W MOSFET power amplifier. A 100W MOSFET power amplifier circuit based on IRFP240 and IRFP9240 MOSFETs is shown here. The amplifier operates from a +45/-45 V DC dual supply and can deliver 100 watt rms into an 8 ohm speaker and 160 watt rms into a 4 ohm speaker. This Hi-Fi amplifier circuit is suitable for a lot applications like general purpose amplifier, guitar amplifier, keyboard amplifier. The amplifier can be also used as a sub woofer amplifier but a subwoofer filter stage has to be added before the input stage. The amplifier has a low distortion of 0.1%, a…

LM3900 multi-channel audio mixer. A simple multi-channel audio mixer circuit using LM3900 quad amplifier is given below. The circuit consists of 4 channel quad amplifier (LM3900). Two mic audio inputs and two direct line inputs are available in this circuit. By adding the same circuit parallel with this, you can increase the number of inputs according to the applications. Each input is connected to the inverting terminal of LM3900.The built in amplifier of each section amplifies every audio input separately and is fed to the output terminals. The output terminal from each channel is connected to a single output line…

In this article, the working and basics of multi-channel surround sound system is explained along with images. The different types of sound systems available and other common sound formats are also explained in detail. Related Articles WORKING OF AMPLIFIERS WORKING OF SPEAKERS MOTIONAL FEEDBACK AMPLIFIER Multi-channel Audio Multi-channel audio systems are widely used in modern sound devices. The term “multi-channel audio” means that, the audio system can be capable of handling multiple audio channels (usually called audio tracks) to rebuild the sound on a multi-speaker setup. Usually two digits separated by a decimal (.) point (2.1, 4.1, 5.1, 6.1, 7.1,…

Tone control circuit. This is just another circuit designed by Mr. Seetharaman Subramanian and time it is a high quality passive tone control circuit that has an overall gain of around 25 with 20dB boost and cut. This circuit needs minimum number of components, is very cost effective and most of the components required can be found from you junk box. Even though an opamp which is an active element is used in the circuit, the tone control section is entirely passive and that’s why the circuit is named so. Description. The circuit consists of two parts. Firstly an op-amp…