This Project is made up with AT89C2051 and the RTC DS1307. It has a large Seven segment display. The standard remote control is used to change the Time...

You usually use PC hardware monitors to keep a close eye on power-supply voltage levels, the speed of system cooling fans, and even the temperature of the CPU. Until fairly recently, this level of system monitoring was reserved for high-end servers running mission-critical applications. However, now that low-cost hardware monitoring ASICs are available, advanced hardware monitoring has become a standard feature in most new PCs...

Despite the popularity of digital devices, real world signals are typically represented by analog signals. Digital control systems process real world analog signals by using an analog-to-digital converter (ADC) to convert analog signals to digital. Conversions back to analog signals are accomplished using a digital-to-analog converter (DAC). Maxim offers a complete line of precision DACs from 8 to 16 bits. It is important to find a DAC that meets to requirements of the application...

Three new linear regulators simplify the design of batteryoperated equipment. The LT®1521 is a 300mA, positive low dropout regulator with micropower quiescent current and shutdown. The LT1175 is a 500mA negative complement with adjustable current limit. A third product, the LT1118, has the unique capability of maintaining output regulation while sourcing or sinking load current...

This very simple circuit just uses a couple of resistors, a capacitor and the easily available 555 timer IC. The 555 is setup as an astable multivibrator operating at a frequency of about 1kHz that produces a shrill noise when switched on. The frequency can be changed by varying the 10K resistor...

These are two - easy to build - relay-based alarms. You can use them to protect your motorcycle - but they have many more applications. If you use relays with 6-volt coils - they`ll protect your "Classic Bike". Both alarms are very small. The completed boards occupy about half a cubic-inch - 8 cc. The standby current is zero - so they won`t drain your battery...

The simplest Metal detector with one BC548

This is the circuit diagram of a low cost metal detector using a single transistor circuit and an old pocket radio..This is nothing but a Colpitts oscillator working in the medium band frequency and a radio tuned to the same frequency.First the radio and the circuit are placed close.Then the radio is tuned so that there is no sound from radio.In this condition the radio and the circuit will be in same frequency and same frequencies beat off to produce no sound...

Speech Pitch Controller (MSM6322GSK)

That circuit uses the MSM6322GSK which is only available in small 24 pin plastic SOP style package. A speech pitch converter IC that operates in real time and requires very few external components. It has a microphone preamplifier and line level input and the output requires only a single transistor to directly drive a loudspeaker. As well as the microphone preamplifier, the IC contains a 4th order low pass filter on input and a 3rd order low pass filter on output. In addition there is a build-in 8-bit A/D converter and 9-bit D/A converter...

Electronic potentiometer schematic

Electronic potentiometer using a standard CMOS logic and analog multiplexers. Pot have low distortion (0.005% less at 1 V rms) and is it easy for beginers to Understanding. In the beginning the art Hi-Fi when in the absence of high-quality potentiometers for volume control using resistive divider, the various stages of the change lever mnohapolohovým switch. Figure 1 is the electronic equivalent of such a volume control. Instead I used a mechanical switch CMOS analog multiplexers. EN signal is collected by either a multiplexer, and so we have 16 steps. ..

This is an extremely simple ADC for the PC. It connects to the parallel printer port, and runs from a 9V battery. All parts are available from Digi-Key Corporation (1-800-DIGI-KEY), and cost is under $20, including box! Input voltage range is 0 to 5 V. Driver software is in Turbo Pascal. I measured the speed to be roughly 1200 samples/sec on an 8 MHz XT, and 5700/sec on the same PC with a 10 MHz 80286/cache accelerator card turned on...

I have used this type of circuits for quick testing of telephone equipment. This is a quick hack that does not exactly resemble the characteristics of the real telephone network, but is enough for this kind if applications. If you want better simulation, change the resistor to 600 ohm and increase the power supply voltage. And by the way you can also feed signals to telephone if you connect the circuit output wires to small amplifier output...

Sub woofers are very popular, with home theatre being one of the driving forces. However, a good sub adds considerably to normal hi-fi program material, and especially so if it is predictable and has good response characteristics.The majority of sub woofers use a large speaker driver in a large box, with tuning vents and all the difficulties (and vagaries) that conventional operation entails. By conventional, I mean that the speaker and cabinet are operated as a resonant system, using the Thiele-Small parameters to obtain a box which will (if everything works as it should) provide excellent performance...

The circuit is designed to work with typical HIFI amplifiers where negative speaker connector (black) is connected to amplifier ground. Be careful here because some modern amps have both terminals actively driven. Connecting either one to a common reference could cause the output stage to smoke...

Logic-Driven adjustable Glow-Plug driver

All of my turbine starts before the research on the ECU involved a very successful spark ignition. I thought (only briefly) of trying to add spark ignition to the ECU, but the mixture of delicate logic circuitry and perhaps 30,000V simply don't mix. My past experience with the hall sensor ignition for the radial engine bears this out in painful detail. So I decided to go with a glow-plug driver...

2 Axis Solar Tracker Circuit

The sun trucker uses a combination of three photoresistors R7, R8 and R9, to ensure that the circuit will follow the sun during the day, but stop working at night time. Make this circuit 2 times to have 4 Axis move, by using 2 motors...