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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...

The essence of the circuit is for the input of tone and signal to provide an activation for the relay switch. Relay – an electrically operated switch where the current flowing through the coil of the relay is creating a magnetic field which attracts a lever and changes the switch contacts, thereby making its state open or close BC214 – a complementary silicon planar epitaxial transistor used in AF small signal drivers and am1 as well as for low noise preamplifier applications due to its feature of good linearity of DC current gain LM741 – a general purpose single operational amplifier with features such as offset null, compensated internal freq uency, voltage range with high input, good stability of temperature, and protected from short circuit The use of relay will allow the circuit to switch from one condition to another. It can also be referred to as a form of an electrical amplifier since it is able to control an output circuit of higher power than the input circuit. There are man...

This 16 LED Chaser Circuit Diagram is a double direction flash. Similar to Digital Ping- Pong 1, there is a movement of a lit dot, up and down along the LED's length. 16 LED Chaser Circuit Diagram When the D16 lit the situation changes and there is a reverse movement. Lit D15-14 ……D16, is lit making circles when the circuit is under power. The IC1 is an unstable flip- flop supplying with stable frequency pulses (the frequency can be changed by TR1, adjusting the velocity of the LED's up and down). This frequency supplies the IC3 (which is a 4-Bit UP and DOWN counter) through 2 gates A-B of the IC2. The output counter supplies the IC4 that is the driver of the LED's. The parts C- D of The IC2, make a R-S flip- flop, that changes situation, when the edge LED's D1 and D16 lit. We have an electronic limit for the situation change. In proportion the shape we make with the LED's, we can have the proportionate optional result, making various effects. Part List R1= 100Kohm...

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...

Project Description This is a very easy to build power supply that is based on LM338 5A adjustable voltage regulator. I am using the supply for a long time, have no problem yet. Only current adjust is missing but I overcome this situation by using an LCD panel ampermeter.  There is no PCB for the circuit. I took a 3x16 copper plate and strip the unused areas by a knife. If you want you can use analog meters instead of LCD panels.    Notes Use thick wires for connections.When connecting the LM338 to the heatsink use thermal paste. Use external supplies for LCD panels. They can be 9V batteries. The panels I use draws 1mA current and the batteries last sufficiently long time. If you have small transformers which can supply regulated 9V, you can use them. You need separate transformers for each panel!The transformer should be 100 Watt but if you don't need high current you can try transformers that you already have. (I can draw 6A from 100Watt transformer.)If you have ...

Build a 250 to 5000 watts PWM DC/AC 220V Power Inverter  This is my schematic design of a Pulse Width Modulator DC/AC inverter using the chip SG3524 . I have built this design and using it as a backup to power up all my house when outages occur. If you like my work and intend to build the circuit don't forget to give me the 5 satrs :D and subscribe to me by clicking on the "follow" button so I know how many people benefit from the design, Thanks Notes: >The schematic circuit design is for a 250 watt output, while the pics are of my 1500 watts inverter that i built, to increase the power of the circuit you have to add more of the Q7 and Q8 transistors in parallel, each pair you add will increase your power by 250 watts, ex: to get 750 watts of power from the inverter you need to add in parallel 2 of Q7 and 2 of Q8 to the original design. >If you increase the power transistors you have to enlarge the T2 transformer to match the new needs, the c...

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 main source of power in a telecommunications system is -48 V. This source’s negative polarity and its large magnitude with respect to ground pose a challenge when designers want to use low-power ICs in the telecom system’s application circuits. Fortunately, the emergence of high-voltage ICs with operating voltages of 75 V and higher has enabled the use of simple biasing techniques in designing circuits for -48-V systems. The technique described here provides a dimming control for an LED. The circuit uses a 65-V hysteretically controlled LED driver (MAX16822A) with its ground pin connected to -48 V and its power input connected to the system ground (Fig. 1). For proper dimming, therefore, the circuit’s logic-level control signal (at Control) must be level-shifted down to –48 V and applied to the DIM input. The high-voltage pnp transistor (CMPT5551) (80 V/500 mA) enables a simple solution to that problem. Logic-Level Signals Dim -48V LED Driver Circuit Diagram The transistor circuit ...

The power line fluctuations and cut-offs cause damages to electrical appliances connected to the line. It is more serious in the case of domestic appliances like fridge and air conditioners. If a fridge is operated on low voltage, excessive current flows through the motor, which heats up, and get damaged. The under/over voltage protection circuit with time delay presented here is a low cost and reliable circuit for protecting such equipments from damages. Whenever the power line is switched on it gets connected to the appliance only after a delay of a fixed time. If there is hi/low fluctuations beyond sets limits the appliance get disconnected. The system tries to connect the power back after the specific time delay, the delay being counted from the time of disconnection. If the power down time (time for which the voltage is beyond limits) is less than the delay time, the power resumes after the delay: If it is equal or more, then the power resumes directly. This circuit has been desig...

The SCC2 is a solar charge controller, it’s function is to regulate the power flowing from a photovoltaic panel into a rechargeable battery. It features easy setup with one potentiometer for the float voltage adjustment, an equalize function for periodic overcharging, and automatic temperature compensation for better charging over a range of temperatures. 10 Amp Solar Charge Controller Circuit Diagram With Parts List The goal of the circuit design was to make a charge controller with analog simplicity, high efficiency, and reliability. A medium power solar system can be built with a 12V solar panel up to 10 amps, the SCC2, and a lead acid or other rechargeable up to a few hundred amp hour capacity. The SCC2 can be operated at battery voltages other than 12V, it can work at 6V and 24V by changing a few parts. Operation at voltages between 6V and 24V is also possible. Specifications Maximum solar panel current: 10 Amps Night time battery drain current: approximately 1ma Nominal battery v...

What is PIR ? Passive Infrared Sensor Circuit Diagram . Detectors or pyroelectric sensors, passive infrared or PIR sensor, are made of a crystalline material that generates an electric charge on the surface when exposed to heat in the form of infrared radiation. When radiation increases the amount of electrical charge increases too and this load is measured with a sensitive FET transistor which is inside the sensor module. With the RIP is commonly used as a motion detector of an object by detecting the infrared signal radiated from the object (people and animals). The Passive Infrared Sensors are also used in remote thermometers. Pinning PIR sensor Pin 1 of the PIR must be connected to the positive supply 5V DC. Pin 2 is the output of PIR sensor, it must have a connection to the earth through a resistor of 47K to 100K (depending on the circuit). Pin 3 of the RIP must be connected to ground or negative circuit. Simple Circuit Diagram using PIR Sensor Simple circuit motion sensor PIR det...

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...

This Auto Anti-Hijack Alarm Circuit Diagram was designed primarily for the situation where a hijacker forces the driver from the vehicle. If a door is opened while the ignition is switched on - the circuit will trip. After a few minutes delay - when the thief is at a safe distance - the Siren will sound. Where it differs from the first two alarms - is in what happens next. I'm obliged to Victor Montanez from the USA who suggested that the engine cut-out should not operate - until the vehicle comes to a stop. That way - the engine will not fail suddenly or unexpectedly. And the hijacker will retain control. I haven't been able to implement Victor's excellent suggestion completely - because I couldn't think of a simple, reliable and universally applicable way of sensing when the vehicle has come to a stop. Instead - I have postponed engine failure until the ignition is switched off. Once the thief turns off the ignition - the engine will not re-start. Clearly - there is ...

This little circuit uses a LM317 variable voltage regulator to adjust the input voltage down to +9 volt, or whatever else you need. Just a solid basic circuit without bells and whistles. You can do with a 10uF capacitor for C1 if your battery is close to this circuit. If it is located more than 3 feet increase the value to 100uF or above. Without a coolrib it can easily handle 500mA. If you need more, or the maximum current (1.5A), then a good coolrib is required. Trimmer potent meter R3 will vary the output voltage. Ceramic capacitor C2 improves frequency/transient response. Can be omitted if not needed for your application. If you want extra protection in case the adjust pin is short circuited, add an extra 1N4001 diode over the input and the output. Cathode to input. But normally only used if the output is way over 25V. R1 and R3 determine the output voltage. You can adapt them for your own needs and applications. Use the following formula: (((R1+R3)/R2)+1)*1.25=V-out which...

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...

This circuit provides a delayed visual indication when a door bell switch is pressed. In addition, a DPDT switch can be moved from within the house which will light a lamp in the door bell switch. The lamp can illuminate the words "Please Wait" for anyone with walking difficulties.  Doorbell Circuit Diagram Notes: The circuit uses standard 2 wire doorbell cable or loudspeaker wire. In parallel with the doorbell switch, S1, is a 1N4001 diode and a 12 volt 60mA bulb. The bulb is optional, it may be useful for anyone who is slow to answer the door, all you need to do is flick a switch inside the house, and the bulb will illuminate a label saying Please Wait inside the doorbell switch or close to it. The double pole double throw switch sends the doorbell supply to the lamp, the 22 ohm resistor is there to reduce current flow, should the doorbell switch, S1 be pressed while the lamp is on. The resistor needs to be rated 10 watts, the 0.5 Amp fuse protects against short circuits. W...

Here’s a blog post that will show you the setup you’ll need to make your own do-it-yourself radio controlled (RC) tankbot from the ground up. This example uses a few kits from Solarbotics to build your own RC controller, communication link, and tankbot using minimal parts. We even managed to get 250 feet of range out of the deal! For this exploit we invite you to move over to the dark side, as the heart of the project isn’t Xbees but instead 2.4GHz IEEE 802.15.4 Radio Frequency Network modules from Synapse Wireless which are actually super simple to use and configure. This post will merely get you started with building a general RC platform, feel free to modify/hack the system to suite your own diabolical requirements.

Build a 10w 225-400mhz Linear Amplifier Circuit Diagram. This circuit broadband amplifier covers the 225-400 MHz military communications band producing 10 watt RF output power and operating from a 28 volt supply. The amplifier can be used as a driver for higher power devices such as 2N6439 and MRF327. The circuit is designed to be driven by a 50 ohm source and operate into a nominal 50 ohm load.   10W 225-400mhz Linear Amplifier Circuit Diagram   The input matching network consists of a section composed of C3, C4, Z2, C5 and C6. C2 is a dc blocking capacitor, and Tl is a 4:1 impedance ratio coaxial transformer. Z1 is a 50 ohm transmission line. A compensation network consisting of Rl, Cl, and LI is used to improve the input VSWR and flatten the gain response of the amplifier.  L2 and a small ferrite bead make up the base bias choke. The output network is made up of a microstrip L-section consisting of Z3 and C7, and a high pass section consisting of C8 and L3. C8 als...

This is a smart battery charger can protect your vehicle's battery from failing and will prolong its life – they're fully automatic so you can connect and forget.

This circuit provides a delayed visual indication when a door bell switch is pressed. In addition, a DPDT switch can be moved from within the house which will light a lamp in the door bell switch. The lamp can illuminate the words "Please Wait" for anyone with walking difficulties.  Doorbell Circuit Diagram Notes: The circuit uses standard 2 wire doorbell cable or loudspeaker wire. In parallel with the doorbell switch, S1, is a 1N4001 diode and a 12 volt 60mA bulb. The bulb is optional, it may be useful for anyone who is slow to answer the door, all you need to do is flick a switch inside the house, and the bulb will illuminate a label saying Please Wait inside the doorbell switch or close to it. The double pole double throw switch sends the doorbell supply to the lamp, the 22 ohm resistor is there to reduce current flow, should the doorbell switch, S1 be pressed while the lamp is on. The resistor needs to be rated 10 watts, the 0.5 Amp fuse protects against short circuits. W...