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The AT89C51 from ATMEL is the most commonly used variation of the 8051 microcontroller because of the built-in Flash which makes programming / burning very easy. The 8051 has a total of 4 ports for input / output operations which means you can transfer data in or out of the microcontroller through these ports. Let's have a brief introduction to these ports. UPDATE: You can also click this link for an updated version of this post. READ MORE

There are only a limited number of switching regulators designed to generate negative output voltages. In many cases, it’s thus necessary to use a switching regulator that was actually designed for a positive voltage in a modified circuit configuration that makes it suitable for generating a negative output voltage. The circuit shown in Figure 1 uses the familiar LM2575 step-down regulator from National Semiconductor (www.national.com). This circuit converts a positive-voltage step-down regulator into a negative-voltage step-up regulator. It converts an input voltage between –5 V and –12 V into a regulated –12-V output voltage. Note that the output capacitor must be larger than in the standard circuit for a positive output voltage. The switched current through the storage choke is also somewhat higher. Some examples of suitable storage chokes for this circuit are the PE-53113 from Pulse (www.pulseeng.com) and the DO3308P-153 from Coilcraft (www.coilcraft.com). The LM2575-xx is availabl...

I am planning on doing an s-video and rca jack mod on my Genesis. The mods I see done seem to all use the headphone jack as the source of the stereo sound. Is this the only way? I would prefer to have the output not be controlled by the volume slider. Is it possible to tap the signals before they go to the amp and route them to my own (fixed-gain) amp? Any help/advice is much appreciated.. visit page.  Line Level Stereo Output on Genesis

The supply receive from 220 /120/110 Volt AC , then lowered by the transformer . Then receives +20 Volts DC from rectifier / filter section. This applied to pin 11 and 12 of the IC uA723/LM723 , as well as to the collector of the 2N3055 series pass transistor. The output through R1 and R2, providing about 7 V with respect to ground at pin 4. The reference terminal at pin 6 is tied directly to pin 5 , the non inverting input of the error amplifier . For fine trimming the output voltage , a potentiometer can be installed between R1 and R2. A 100-pF capacitor from pin 13 to pin 4 furnishes gain compensation for the amplifier. Base drive to the 2N3055 pass transistor is furnishes by pin of the uA723. Since desired output of the supply is 1 Ampere, maximum current limit is set to 1,5 Ampere by resistor Rsc whose value is 0,422 Ohm. A 100uF electrolytic capacitor is used for ripple voltage reduction at the output. A 1 kOhm output resistor provides stability for the power supply under no - lo...

This is an On Air indicator , ie an indicator circuit dr RF transmission , very simple and useful for those who like RF . This circuit detects the RF output using a visual indicator , but with some modifications , the LED may be replaced by a relay or any other system that want to trigger when the transmitter is switched on. The output of the transmitter or other RF generator must be connected to this RF input circuit.   Simple Circuit indication for RF Output Transmitters List of components Resistor R1 560Ω eighth Capacitor C1 330pF disc C2 Capacitor 0.1μF disc Diode D1 1N34 or 1N60 D2 LED Transistor Q1 2N3904 or equivalent  If you liked this article,Take a few Seconds to Share this and leave comments

This is a Touch Switch with Digital Output Circuit Diagram control key by touch simple, it uses a 4011 IC. The output logic HI has its pulse delay time controlled by C1. In the case is C1 4.7uF controls the pulse width for 1 second, then the touched the plate. Nothing prevents you from being done tests with other values ​​of C1. Touch Switch with Digital Output Circuit Diagram

This circuit operating with IC uA723 and add amplified with transistor  TIP31 or similiar transistor with TIP31 . Input voltage for circuit about 10 - 40 volt DC , formerly of AC voltage 220 volts or 110 volts , then lowered by the transformer voltage to 30 volts. And the supply output voltage from 1 volt to 35 volt DC  you can adjust it on potentiometer  R2 .  See this circuit power supply below : Output voltage transformer used 10 to 40 Volts . On resistor Rsc is the current limit set resistor. Its value is calculated as : Rsc = 0.65 Volt For Example : If you need current output 2.0 A Rsc = 0.65 / 2.0 = 0.32 Ohm So , you must use 0.32 Ohm to current output 2.0 A