Mutchus

How to Build a Bipolar Power supply for Battery instruments . A bipolar power supply overcomes those limitations. Most importantly, it can provide both positive and negative voltages from a single pair of terminals. There are no relays to switch polarity, so a bipolar supply can move smoothly from positive, through zero, to negative voltages.   Bipolar Power supply for Battery instruments Circuit Diagram It also regulates zero volts or other very small voltages. In this Bipolar Power supply for Battery instruments circuit diagram to generate regulated ± 5-V supplies from a pair of dry batteries, the circuit of Fig. 1 is commonly used. In order to give protection from inadvertent reverse connection of a battery, a diode in series with each battery would produce an unacceptable voltage drop.  The more effective approach is to fit diodes Dl and D2 as shown in Fig. 2, in parallel with each battery. When the supply is switched off, there is the risk of a reverse bias being ...

Watching movies is a neat escape from the stressful lifestyle we live in. Watching movies in a wide screen and surround sound take you far away and into the movie scene you are watching. You watch it as if you were there in the movie scene. Of late, we can only experience this escape in a cinema. However, modern technology may be able to provide this same sight and sound experience right in your own living room. We will discuss the basic components of a home theater system in this article. Read on to understand how these basic components can deliver the best cinematic experience to a home theater system. Home theater experts state that the most important consideration in setting up a home theater system is the size of the room where you will set up the home theater system. The most important component of the home theater system, which is the television, is dependent on the size of the room. Although, the recommendation is 27 inches television set at a minimum is necessary for your home...

Theory of operation remain the same so please take a look at the previous Article about MAINS Power Switch for deeper explanations. I don’t know if this it’s the smallest MAINS Power Switch with integrated WIFI and direct Web interface access but if is not, it’s definitely closer to be at only around 25x50mm :) [ ]

The circuit comprises a timer IC 555 wired as an astable multivibrator with adjustable time period of 15 seconds. The astable output after inversion by an inverter drives decade counters IC3 and IC4 (each IC 7490) connected in cascade.  Timer for Geyser Circuit Diagram The decade counters output is connected to decoders IC5 and IC6 (each IC 7442), respectively. The decoder outputs (Q8 outputs of IC5 and IC6) are fed to inverters and the inverter outputs, in turn, are fed to an AND gate. The AND output is connected to the reset pin of the astable multivibrator built around another timer IC 555 to sound the alarm. Now you can turn off the geyser. A green LED (LED1) has been used as the power supply indicator. Switch on the timer and the geyser at the same time. When the alarm sounds, it means that the water in the geyser has heated up and can be used.You can assemble the timer circuit on a general-purpose PCB and install it near your bathroom so that both the timer circuit and the ge...

Going for Gold Circuit Diagram   The title refers to a popular TV game show where the contestants each have a big button.  The  game show  host  asks  a  question and the first contestant to press their but-ton makes an illuminated indicator light up on their desk. The other contestants’ buttons  are automatically inhibited, so that everyone can see who was the first contestant to press their button, and so is allowed to answer the question. The project described here shows how to build a similar sortof  refereeing device yourself, using simple resources and without needing a microcontroller, which is  pretty rare these days! The basic circuit is for  just two contestants, but the modular design  means it can easily be expanded.   Going for Gold Circuit Diagram The diagram shows three buttons: S2 and S3  are the buttons for the two contestants, S1 is  the button for the host, which allows them to  reset th...

Hi all, today I'll share you the full source code of Led Cube 8x8x8 project . In this project, I'll write Assembly code on an 8051 MCU or 89c52 microcontroller. Because the source code is completely in asm, they're very suitable for MCUs whose memory is limited. Below is the video for demonstrating many interesting effects of the 8x8x8 Led Cube. Video Demo 8x8x8 Led Cube Circuit Diagram (Proteus) to download source code: http://www.mediafire.com/download/ajg20l3tedjrdwa/cube_8x8x8.rar Create your own 8x8x8 LED Cube 3-dimensional display!We believe this Instructable is the most comprehensive step-by-step guide to build an 8x8x8 LED Cube ever published on the intertubes. It will teach you everything from theory of operation, how to build the cube, to the inner workings of the software. We will take you through the software step by step, both the low level drivers/routines and how to create awesome animations. The software aspect of LED cubes is often overlooked, but a LED cu...

Ham Com is a modem for almost all types of digital transmission for radio amateurs. It can be used to RTTY, ASCII, NevTex, Sitor, Amtor, Fec, CW, FSK, etc.. The modem is simple and can even be used for receiving faxes and SSTV wx-using JV-FAX software.  Modem for Digital Modes Circuits Diagram To use this modem, you need a PC with serial port, Software HamCom and radio equipment.

This circuit will allow you to turn on any piece of equipment that operates on 115 volts ac. The receiver circuit is based on the Radio Shack infrared receiver module (MOD), part number 276-137. It is also available from some of the other sources listed on my s page. The MOD accepts a 40khz IR signal that is modulated at 4 khz. Circuit Diagram When a signal is received the MOD will go low. The sensitivity of the MOD is set by different values for R1 and C1. The values for R1 may need to be as high as 10,000 ohms and for C1 40uf. This will prevent the unit from turning on under normal lighting conditions. You will need to experiment with the values that work best for you. The output of the 4013 chip a flip flop toggles on and off with the reception of a IR pulse. The output of the 4013 turns on the MOC optical coupler which in turn switches on the triac and supplies power to the AC load.

This regulator was designed for use with a  generator with a higher output voltage. This  type of generator can be found on some boats  and on vehicles for the emergency services.  They are really just an adapted version of the  standard alternator normally found in cars.  The field winding is connected to the 12 V  (or 24 V) battery supply, whereas the generator winding is configured for the AC grid  voltage (230 V or 115 V). This AC voltage now  has to be kept stable via the 12 V field winding. Although it’s perfectly possible to use a  switching regulator for this, we deliberately  chose to use the old and trusted 723. The generator is a three-phase type, with the  field winding rated for 12 VDC. The output voltage of the generator depends on its revs  and the current through the field winding.  Since the output voltage is relatively high, it  is fed via opto-couplers to the 723, which is  used in a standar...

Nokia has started rolling out its Windows Phone 8 'Amber' update for its Lumia smartphone lineup, which brings with it a number of major software improvements. Nokia's Amber update builds on Microsoft's most recent Windows Phone 8 update and sees the Finnish firm further outdoing HTC and Samsung with unique Windows Phone features. The most notable new aspect is Amber's added camera features. The update adds Nokia's Pro camera app that debuts on the Lumia 1020 to some of its older phones, including the Lumia 920 and Lumia 925. Nokia's Smart Camera app is also made available to more devices, as the Amber update sees the app arriving in the Windows Store. Detailing the Smart Camera app on its blog, Nokia said, "The app brings a slew of different options – use Best Shot to find the sharpest image from a series of ten; combine several shots of people in movement into one with Action Shot; heighten the appearance of speed by blurring the background with Motio...

The RF sweep frequency generator (‘wobbu-lator’) published in the October 2008 issue of Elektor has a receiver option that allows the instrument to be used as a direct conversion receiver. This receiver does however have a noise floor of only –80 dBm, which really should have been –-107 dBm to obtain a sensitivity of 1 µV. So, for a good receiver sommore gain is required. A wideband amplifie however, generates a lot of additional noisas well and as a consequence will not resuin much of an improvement.  As an experiment, the author developed a selective receiver with a bandwidth of about 4 MHz. Because a gain of at least 35 dB is required, the preamplifier consists of two amplifying elements. The input amplifier is designed around a dual gate MOSFET, type BF982. This component produces relatively little noise but pro-vides a lot of gain. The output stage uses a BFR91A for some additional gain. Preamplifiers where both the gate and the drain are tuned often struggle with feedback via the...