Audio level meter (vumeter)

This circuit uses just one IC and a very few number of external components. It displays the audio level in terms of 10 LEDs. The input voltage can vary from 12V to 20V, but suggested voltage is 12V. The LM3915 is a monolithic integrated circuit that senses analog voltage levels and drives ten LEDs  providing a logarithmic 3 dB/step analog display. LED current drive is regulated and programmable, ...

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Obstruction Detector With 12C508 IR

DescriptionThis project is inspired by the DPRG IRPROX project. They have a pretty good PCB layout and idea. I would like to thank them for posting their project for all of us to see and learn from, I wouldn’t have started PIC programming without them, or at least not nearly as quickly come up to speed! The pinout on my board allows either a five-wire or a four-wire connection to be made the former uses a disable line if desired. You can also put in a resistor or use a trimpot to adjust range. The trimpot locations are very generic, most pots will fit. Be careful not to adjust pot to 0 ohms! The IR proximity detector works very well,...

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Proximity Detector Circuit Based 555 IR

Description Sometimes you want a simple solution to a problem and you don’t mind if your main controller has to do the work. This IRPD requires the main robot processor to choose which side to look at, and requires it to “debounce” the results for reliably operation. But, it still works really well without any complex program code. The NAND gate is a standard 74LS00 that you can get anywhere – even Radio Shack, same with the 555, IR detector (RS Everlight or Sharp GP1U58Y) and IR LEDs can also be gotten at Radio Shack. Parts are easy to find and simple to connect. This does not require any fancy wiring or parts placement. Make sure...

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High Voltage Generator/Solid State Tesla Coil

Parts R1 27 Ohm 5W Resistor or 27 Ohm 10W Resistor R2 240 Ohm 5W Resistor or 240 Ohm 10W Resistor BR1 50 Volt, 6 Amp Bridge Rectifier C1 8000uf, 35 Volt Capacitor Q1, Q2 2N3055 NPN Power Transistor T1 24V 5A Transformer (See “Notes”) T2 TV Flyback Transformer (See “Notes”) S1 115V 3A SPST Switch MISC Case, Wire, Heatsinks, Line Cord Notes 1. T2 is a high voltage flyback transformer salvaged from an old TV, or ordered from Fair Radio Sales (see Where To Get Parts). Look for the biggest, most intimidating transformer you can find. Old tube TV’s are a good place to look. The transformer should not have a rectifier built in. 2. You will need...

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Several RC5 Infrared Transmitter Circuit

 1-channel transmitter with 16 selectable codes (PIC12C508) RC5 is not suitable as a barrier to race out to whoever is the winner. Two or more RC5 channel interfere with each other and the protocol itself also takes time for the transfer. If more than one car with RC5 transmitter arrive close together, it can well be the first and the second triggers the stopwatch. IR does not pass through optical barriers through. Two car side by side is thus not before. Infrared is used in daylight outside, not really a good idea (the sun bothers!). With luck we can get a LOT still to reach 3m. Some wondered whether it was possible to hold down...

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40 Watt Fluorescent Strobe Lamp Schematic

Part List: C1/C2 2x Elko standing 1μF/16V C3 1x Ker. Scheibenkondens. 0.1 μF C4 1x HV-capacitor 1μF 350V axial C5 1x Elko stand. 470μF 25 V C6 1x Poly condensation. 0.068 μF 630V D1-4 4x Diode 1N4001 D5 1x Diode 1N4007 L1 1x Ignition coil (such as the normal speed camera strobe) P1 1x Poti 6mm 2.2 M R1/R4 2x Resistor 470R 1 / 4 W R2/R9 2X Resistor 47K 1 / 4 W R3 1x Resistor 10K 1 / 4 W R5 1x Resistor 270R 1 / 4 W R6 1x Resistor 1.2 K 1 / 4 W R7 1x Resistor 22K 1 / 4 W R8 1x Resistor 120K 1 / 4 W Si1 1x Backup medium time 160mA Si2 1x A pair of fuse holders T1/T2 2x ...

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Hammond Transformers 6V6 Push-Pull Tube Amplifier

This 6V6 amp was built following the push-pull (PP) EL84 / 6V6 Dynaco A-410 output transformer schematic. There are a few minor deviations from the original schematics. Instead of Dynaco transformers, Hammond 1608A audio output transformers and a Hammond 272HX power transformer were used. The EL84 / 6V6 PP Dynaco A-410 output transformer schematic showed a 1000 ohm feedback resistor which resulted in bad amplifier oscillation. Feedback resistor Values between about 6 and 10 k-ohm worked well and I settled on 10k. A 5Y3 rectifier would have been to small for a stereo amp so a JJ GZ34 rectifier was used. It became necessary...

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Atmel at89c51 Office-Home Security System

Home security project Securiy is a matter of great concern to all of us in this world. Normally there are four types of security threat to our property. 1 )Thief, an inturder.2)Fire, so we use fire sensor.3)Water spilage /over flow, so we use water sensor.4) Gas leak , we use gas sensor, whenever there is security breach from one of above or any combination of above.The project takes the following action1) Sounds an ALARM to attract your home Security project or public attention .2) If the reset sw is not pressed within 30 seconds the projects takes further action,3) It makes an emergency call to deliver an emergency message stored in speech...

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12V Stroboscope 250-400V DC Circuit

The stoboscope tube needs about 250-400V DC to operate. This high voltage is generated using simple voltage step up circuit built from transistors Q1,Q2 and transformer T1. This circuit gives out about 230V AC voltage which is then rectified with rectifying bridge U1 (must have at least 400V voltage rating) and stored to the main capacitor C1. I built my stroboscope from parts taken from old camera flash unit. This approach gave me nice flash tube with reflector, trigger transformer and some of the capacitors (for example C1). Other parts were the one luying around. I used some strange triac I found in my for the triggering circuit,...

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Output Relay Delay Audio Amplifier Circuit

Output Relay Delay Audio Amplifier Circuit This is a simple circuit which I built to one of my audio amplifier projects to control the speaker output relay. The purpose of this circuit is to control the relay which turns on the speaker output relay in the audio amplifier. The idea of the circuit is wait around 5 seconds ofter the power up until the spakers are switched to the amplfier output to avoid annoying “thump” sound from the speakers. Another feeature of this circuit is that is disconnects the speaker immdiatly when the power in the amplifier is cut off, so avoinding sometimes nasty sounds when you turn the equipments off. Output...

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10.58 to 10.74 MHz VFO Oscillator Circuit

Figure 1, below, shows the 10.58 to 10.74 MHz VFO oscillator circuit. Yes, this is the same circuit that was presented last time, but I’ve re-drawn it to show the Colpitts oscillator more clearly. “L” is approximately 1.5 uH; 19 turns in a T50-6 core (yellow). The value of C6 is found experimentally. I used 69 pF (a 47 pF and a 22 pF in parallel). More about this during check-out. 10.58 to 10.74 MHz VFO Oscillator Circuit “L” and the V V C along with C6 make up the parallel-tuned circuit that determines the frequency of the VFO. The V V C is an MV2104. Capacitors marked with an asterisk must be silvered mica, COG, or NPO. You might...

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RS-232 Reset for Microprocessor

RS-232 Reset for Microprocessor Introduction This circuit allows a remote microprocessor to be reset by a controlling host by sending a break signal over an RS-232 or RS-422 serial line. If the remote machine resets into a simple program loader program, it is possible for the host to halt and restart, or halt and reload/restart the remote machine’s program. This is an ideal way to develop software on older EPROM-based systems. Modern EEPROM/NVRAM systems use JTAG interfaces for similar results.The remote processor runs its target code out of RAM, allowing the code to be updated easily. The circuit is usually used for developing code...

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Isolated RS422 Interface Circuit and Layout

 Isolated RS422 Interface Circuit Figure 1 shows the circuit diagram of RS422 interface. Connector K1 is linked to the serial port of the PC, power to the PC side of the circuit is derived from the signal lines DTR and RTS. Positive supply is derived from RTS and negative supply from the DTR line. Optical isolation is achieved by optocouplers U1 and U2. Optocoupler  U1 provide TXD line isolation while optocoupler U2 provide RXD line isolation. The other side of the isolator carries TTL levels. This side is powered by an unregulated dc supply between 9V and 12V ac/dc adapter. IC U5 provide 5V regulated output and ICs U3 &...

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0-1000 Volt Regulated High Voltage Power Supply IC 7805

1000 Volt DC to DC Regulator Circuit Input voltage from high voltage DC DC converter is 12V AC at 800mA current and then converted to DC through a bridge rectifier Diode 1A. The voltage output of converter circuit can be adjusted in the range of 0-1000V DC. This high voltage DC DC converter uses the transformer as a base and several other active components include 555 timer IC, CMOS IC 4001, IC voltage regulator 7805, some NPN transistors and a pair of logic MOSFET IRF510 as a final amplifier.The workings of high voltage DC to DC converter is the same principle as written in previous articles. The difference shown is this converter...

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AC to DC 90 Watt Switching Power Adaptor

AC to DC 90 Watt Switching Power Adaptor Circuit AC to DC switching power adaptor circuit with maximum output power of 90W. Switching power supply is built using a high voltage power switching regulator IC MC33374 and some other additional components. The MC33374 IC is a monolithic high voltage power switching regulators that are specially designed to operate directly from a rectified AC line source, and in flyback converter applications.The MC33374 switching power adaptor combines the required converter functions with a unique programmable state controller. At various variable AC inputs, it is capable of serving up to 6 A current...

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12V DC Motor Wind Turbine

12 volt Wind Turbine It is possible to use a 12V DC motor (I assume its a car starter motor) as a wind turbine generator to provide energy conversion between the mechanical torque from the wind rotor turbines, (called the prime mover) and the connected 150V load. A gearless two or three bladed upwind wind turbine using a permanent magnet DC motor can be used to charge a battery for energy storage through a rectifier and a typical wind turbine configuration is given as: Generator Configuration However, using a low voltage DC motor as a wind turbine generator is not always a good idea for the following reasons.The DC motor may not...

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Broadband Random Noise Generator

Broadband Random Noise Generator Circuit This circuit is normally necessary in testing any sort of electronic methods for example filter, audio, or RF communication. The circuit introduced right here generates an RMS amplitude regulated noise source with selectable bandwidth. This circuit is work depending on op amp. This will be the figure with the circuit. Look at the schematic of Broadband Random Noise Generator Circuit above. With 1 KHz to 5 MHz ten years ranges selectable bandwidth and 300mV RMS output, this noise generator is suitable for wide range of software. Noise is created by D1 that is AC coupled to A2, an amplifier with...

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Two Speed Contactor DC Motor Controller Circuit

The simplest of all motor controllers (besides a straight on/off switch) is the contactor controller. I designed this contactor controller for use in my electric scooter project. It is based around three 12V relays, two 12V batteries, two switches and of course a motor. Having no silicon to “fry”, it is quite reliable and robust. A contactor controller works by rearranging the two (or more) supply batteries between series and parallel. This gives the motor a slow speed (batteries in parallel, current adds) and a fast speed (batteries in series, voltage adds). This assures that both batteries are discharged equally. When the circuit...

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Counter Wall 7 Segment Circuit Diagram

This simple counter can be used to count pulses, as the basis for a customer counter (like you see at the doors of some stores), or for anything else that may be counted. The circuit accepts any TTL compatible logic signal, and can be expanded easily (see Notes). Notes 1. All pulses to be counted are to be TTL compatible. They should not exeed 5V and not fall below ground. 2. You can add more digits by building a second (or third, or fourth, etc…) circuit and connecting the pin 11-6 junction of the 74LS90 and 74LS47 to pin 14 of the 74LS90 in the other circuit. You can keep expanding this way to as many digits as you want. Part Total...

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Stepper Motor Pulse Generator with 555

The 555 Stepper Motor Pulse Generator kit will support you together with the pulse needed to drive your favorite DC Servo Motor application. This kit uses the well-known 555 timer IC for creating the Stepping Pulse. Quick Overview # Input : 5 to 12 VDC @ 25 mA # TTL/CMOS interfaceable # Jumper selectable two speed operation # Onboard preset to vary the frequency # Power-On LED indicator # Terminal pins for easy interfacing of the kit # Four mounting holes of 3.2 mm each # PCB dimensions 39 mm x 37...

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Lightning Detector Circuit

This Do-it-yourself lightning detector circuit can be a especially sensitive static electricity detector which can supply an early warning of approaching storms from inter-cloud discharge properly prior to an earth-to-sky return strike takes location. An aerial (antenna) formed of the brief duration of wire detects storms inside a two mile radius. The circuit emits an audible warning tone from a piezo buzzer, or flashes an LED for each discharge detected, providing you advance warning of impendig storms so that precautions may be observed.The primary characteristic inside the lighting detector is the circuit’s ability to be set near...

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CD4001 Simple Alarm Circuit For Motorcycle

Simple Alarm for motorcycle with a CD4001This is a simple alarm circuit for a check with a 4001. You can use it to protect our home, motorcycle, car or any other application that comes to mind. In this circuit you will make a computer simulation with Livewire and then design the printed circuit Kicad.OPERATION SW1 is a normally closed switch when pressed triggers the flip-flop formed by the two NOR gates of the CD4001 and remains in that state for a time determined by the time constant of R5-C2. This time is the one who keeps the relay RL1 and operated by its two contacts that we investors will control two loads, for example a siren...

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Phase Delay Network for 3D Audio Enhancement

3D enhancement is needed to create a fully 3-dimensional sound for most stereo multimedia products. Usually, simple phase-delay circuits is used to produce a widening effect on the perceived sound field. However, there is transaural acoustic crosstalk effect. The following figure shows transaural acoustic crosstalk effect and schematic diagram of simple phase-delay circuits ...

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7 segment rolling display using PC

 It is very interesting and convenient to be able to control everything while sitting at your PC terminal. Here, a simple hardware circuit and software is used to interface a 7-segment based rolling display. The printer port of a PC provides a set of points with some acting as input lines and some others as output lines. Some lines are open collector type which can be used as input lines. The circuit given here can be used for interfacing with...

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PC based Frequency Meter

Here is a simple technique for measuring frequencies over quite a wide frequency range and with acceptable accuracy limits using a PC. It follows the basic technique of measuring low frequencies, i.e. at low frequency, period is measured for a complete wave and frequency is calculated from the measured time-period. Cascaded binary counters are used for converting the high-frequency signals into low-frequency signals. The parallel port of a computer...

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Simple Analog to Digital Converter

Normally analogue-to-digital con-verter (ADC) needs interfacing through a microprocessor to convert analogue data into digital format. This requires hardware and necessary software, resulting in increased complexity and hence the total cost. The circuit of A-to-D converter shown here is configured around ADC 0808, avoiding the use of a microprocessor. The ADC 0808 is an 8-bit A-to-D converter, having data lines D0-D7. It works on the ...

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Control electrical appliances using PC

Here is a circuit for using the printer port of a PC, for control application using software and some interface hardware. The interface circuit along with the given software can be used with the printer port of any PC for controlling up to eight equipment . The interface circuit shown in the figure is drawn for only one device, being controlled by D0 bit at pin 2 of the 25-pin parallel port. Identical circuits for the remaining data bits D1 through D7 (available at pins 3 through 9) have to be similarly wired. The use of opto-coupler ensures complete isolation of the PC from the relay driver circuitry. Lots of ways to control the hardware...

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