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A milli Amp analog meter often used along with audio system can be easily converted into a decent volt meter, all that is needed is an understanding of the requirement and the meter. In case a 10V full scale meter is to be designed, then a 10K resistance is to be put in series with the meter coil so that for an applied voltage of 10V a meter can receive 1milliAmp only. The meter itself has an internal resistance and if that is measured properly then in actual practice the resistor to be connected in series shall be having a value of 1000 ohms – IR (internal resistance of the meter). When we measure smaller voltage then this internal resistance of the meter plays a significant role, say for this particular case the internal resistance is 86 ohms, hence, for a I.V. full scale meter the value of the external resistance would be (1000-86) 914 ohms. The milli amp meter can also be used as an Amp meter of higher currents by adding shunt resistances. This is being achieved by simple net...

In the early 1960s RCA brought out a transistor that was to become truly legendary: the 2N3055. With a pair of these devices, you could put together an audio power amplifier that could deliver a healthy 40 W into 8 Ω. The circuit described here is fully in tune with the spirit of that era. For example, there are only seven active components in each channel, which reflects the design simplicity typical of that era (and actually a timeless quality). This ‘retro’ power amplifier pumps 45 W into 8 Ω with an input signal level of 0.5 Vrms. It works as follows: the input signal is applied to the base of T1, while negative feedback from the output, attenuated by voltage divider R5/R6, is applied to the emitter of T1. The collector current of T1, which is proportional to the difference between the input and feedback signals, is fed to the base of T2. This transistor draws its operating current through R8 and R9 and provides voltage gain. Capacitor C6 is a bootstrap capacitor that hold the volta...

Why a lamp tester or fuse tester? Testing cables, wires, lamps… belongs to a repair job and sometimes this becomes too cumbersome since one has only two hands and too often, one has to hold the part being tester and the two probes of an ordinary continuity tester all at the same time. This fuse and lamp tester enables easy testing of lamps and fuses by using the conductivity of the human body. One of the test probes is connected to the part under test while the other probe is hel dby the normal hand. When the lamp or fuse is working properly, your eyes will glow in the dark! Just kidding :) . When the lamp or fuse is working properly, a small amount of current flows through the hand which is enough to switch the transistors and light the LED.

In the world of electronics, vacuum tubes are almost obsolete. Nearly the last holdout, the cathode ray tube (CRT), is rapidly being replaced by the LCD and other new technologies. Despite this trend, the vacuum tube has seen a big revival in the field of guitar amplifiers, and to a lesser extent, hi-fi amplifiers . Vacuum tubes and related parts have become more readily available in recent years as numerous companies have tapped into this market. The reason for the popularity of tubes in guitar amps involves the nice tones that are produced when tubes are driven to the point of distortion. For some background on this, follow some of the links on The Strat Monger. There are numerous solid state "modeling amps" that try to simulate vacuum tube amps with digital signal processing (DSP) techniques, but in the end, that method is never more than a simulation. It just ain't the same as the real thing. One can spend a large amount of money and time building a tube amp from scra...

Have you ever connected two PCs together via modems using a twisted pair cable and nothing happened? That’s because the modems are expecting a phone line with all the signals and voltages supplied by the local telephone exchange. This circuit simulates the DC power and signal isolation but not the "dial tone" or the "ring signal". It suffices to connect two PCs together to communicate and exchange files using HyperTerminal. The circuit is self-explanatory and needs only one power supply for both modem lines. Although 50V DC is the usual exchange line voltage, this circuit should operate down to 20V. A 600O line transformer (eg. Jaycar cat. MM-1900) provides signal isolation, while the resistors provide current limiting and keep the lines as balanced as possible. Circuit diagram: How To Connect Two PCs Using Modems Circuit Diagram When using this set-up with HyperTerminal, you should not select a Windows modem driver in the "Connect To" dialog. Instead, con...

Normally cell batteries have a shelf life of 2 to 5 years under normal use . After that time we have to replace them . Nowadays there replacement batteries which are cheap, but these batteries last for much less cost only months. An easy solution is to use batteries in a circuit that requires less current , we can use them for lighting LEDs .  How to Reuse Old Cell Battery for LED lighting 

This is a Simple LED Volt meter to Monitor the charge level in Lead Acid Battery or Tubular battery. The terminal voltage of the battery is indicated through a four level LED indicators. The nominal terminal voltage of a Lead Acid battery is 13.8 volts and that of a Tubular battery is 14.8 volts when fully charged.  Simple LED Volt Meter Circuit Diagram The LED voltmeter uses four Zener diodes to light the LEDs at the precise breakdown voltage of the Zener diodes. Usually the Zener diode requires 1.6 volts in excess than its prescribed value to reach the breakdown threshold level. When the battery holds 13.6 volts or more, all the Zener breakdown and all LEDs light up. When the battery is discharged below 10.6 volts, all the LEDs remain dark. So depending on the terminal voltage of the battery, LEDs light up one by one or turns off.

The Different Types of Resistor Resistors, (  R  ) are the most fundamental and commonly used of all the electronic components, to the point where they are almost taken for granted. There are many different  Types of Resistor  available for the electronics constructor to choose from, from very small surface mount chip resistors up to large wirewound power resistors. The principal job of a resistor within an electrical or electronic circuit is to “resist” (hence the name Resistor ), regulate or to set the flow of electrons (current) through them by using the type of conductive material from which they are composed. Resi stors can also be connected together in various series and parallel combinations to form resistor networks which can act as voltage droppers, voltage dividers or current limiters within a circuit. A Typical Resistor Resistors are “ Passive Devices “, that is they contain no source of power or amplification but only attenuate or reduce the voltage or c...

An optocoupler (or an optoelectronic coupler ) is basically an interface between two circuits which operate at different voltage levels. The key advantage of an optocoupler is the electrical isolation between the input and output circuits. With an optocoupler, the only contact between the input and output is a beam of light. Because of this it is possible to have an insulation resistance between the two circuits in high voltage applications where the potentials of two circuits may differ by several thousands of volts. Read More.....

Online mega-retailer Amazon may be planning to release an Android -based gaming console by the end of the year, if rumors prove correct. Citing "those ... who have knowledge of the in-development hardware," Game Informer claims Bezos & Co. may be readying the device to ship by "Black Friday" – the day after the US Thanksgiving holiday, traditionally the start of the holiday shopping season, which this year falls on November 29. Details of the plan are virtually nonexistent, but this isn't the first time El Reg has heard murmurs that Amazon may be planning to broaden its hardware line beyond its Kindle e-readers and tablets. In May, The Wall Street Journal reported that Amazon was operating a secretive facility in Apple's hometown of Cupertino, California, known only as "Lab 126," where it was working on at least four hush-hush hardware projects. Two of those were said to be Amazon -branded smartphones, a perennial topic of discussion among r...

Circuit diagram The LM1036 is a DC controlled tone (bass/treble), volume and balance circuit for stereo applications in car radio, TV and audio systems. An additional control input allows loudness compensation to be simply effected. Four control inputs provide control of the bass, treble, balance and volume functions through application of DC voltages from a remote control system or, alternatively, from four potentiometers which may be biased from a zener regulated supply provided on the circuit. Each tone response is defined by a single capacitor chosen to give the desired characteristic. Features: Wide supply voltage range, 9V to 16V Large volume control range, 75 dB typical Tone control, ±15 dB typical Channel separation, 75 dB typical Low distortion, 0.06% typical for an input level of 0.3 Vrms High signal to noise, 80 dB typical for an input level of 0.3 Vrms Few external components required Note: Vcc can be anything between 9V to 16V and the output capacitors are 10uF/25V elect...

Hello everyone. Today we’re going to do a setup on a Les-Paul-style guitar. For this post, I’ll be setting up a “Burny Super Grade” guitar, but the set up is the same for most Les-Paul-style guitars. I already have a general electric guitar setup post over here: http://diystrat.blogspot.com/2011/03/how-to-set-up-electric-guitar.html, but there are a few Les Paul specific areas I’d like to go into here. Before I start, I want to mention a few things about this particular guitar. It looks and (potentially) sounds great. The neck plays well too, but it has some tuning problems and buzzes a bit more than I’d like. The tuning problems are coming from two areas. Firstly the nut slots are too tight, made evident by the strings making a pinging noise when they are tuned up or down. This means that it is difficult to fine tune, as the string’s pitch tends to “jump” up or down. The second reason for the tuning issues is that the intonation is way out. By that I mean that the saddles’ forwards/ba...

Description If you forget to switch off the light after leaving a seldom used room (such as the loft), there’s a strong likelihood that it could remain lit for months, running up an expensive power bill in the process. How can we prevent this waste? It’s not hard for electronics enthusiasts to design a little circuit to mitigate the effects of absentmindedness. The notion is simple; if the light is left on when the hatch or door is closed, a rhythmic sounder/buzzer signal produces an alarm that hopefully will not be masked by other noise. The circuit is powered as long as the lamp bulb is switched on by light switch S1. If the reed switch S2 then signals that the hatch has been closed, the sounder operates. The red LED, mounted outside the loft next to the entry hatch, also indicates that the lamp up there needs to be switched off. The circuit does not use a transformer, meaning that the whole circuit is at mains potential. For this reason the components must be placed inside an insu...

Often we do not have the opportunity or the money to keep our hobby, sometimes we lack tools, but always there is a knack for everything, is what we see here in this article was originally published at indestructible. He teaches you how to make your own breadboard using scrap old computers, in fact it uses sockets IDE cable. The breadboard makes life easier for those who like to create electronic circuits, and can only plug components without using solder.