Mutchus

Who never used a multimeter Chinese yellowing that shoot the first resistor! Despite being heavily criticized, this multimeter is identical to any other, is a lightweight tool, compact, inexpensive and reliable. It has as main component IC 7106, which is an analog to digital converter, with output to liquid crystal display (LCD) 3 and 1/2 Digits.  The Marcelino (which may have other colors), has several brands and models, but his real name is 830, there are versions without the test transistors, there are also variants with signal generator 50Hz, thermometer, continuity test with back-light, etc. This multimeter can measure DC Volts 0.1 mV to 1000V, AC Volts 0.1V to 750V, Ampere DC 0.1 mA to 10A, Ohm 0.1 Ω to 2MΩ, diode and hFE for bipolar PNP transistors and NPN. Basic scheme of Digital Multimeter circuit diagram  

Joe Collier and Kai Wei Tang created a concept cell phone Light Phone size of a credit card, which is connected to the main cell phone and has only the function calls. 

This circuit can control the direction of a DC motor., It has many applications that are necessary to operate a motor in both directions, clockwise and counter-clockwise (forward and backward). One way to accomplish this is to start the engine in a circuit arrangement of transistors called H-bridge. H bridge is an electronic circuit which enables a voltage is applied across a load in either direction. This circuit is often used in robotics and other applications to allow DC motors to become bi-directional. H-bridge Control the Direction of Rotation for DC motor Circuit Diagram List of components PARTS LIST R1, R2, R3, R4 220Ω R5, R6, R7, 1K Ohm D1, D2, D3, D4 1N4001 D5, D6 LED Q1, Q2 2SD313 Q3, Q4 2SB507 PB1, PB2 switch M1 12V DC MOTOR In this circuit usually PB1 and PB2 are open. Thus, the bases of the transistors are grounded. Hence Q3 and Q4 are turned on, Q1 and Q2 are turned off. The voltages at both terminals of the motor is the same and thus the engine is switched off. Similarly...

Circuit Enables PCs to Communicate via IrDA Introduction of IRDA The Infrared Data Association ( IrDA ) is an industry driven interest group that was founded in 1993 by around 50 companies. IrDA provides specifications for a complete set of protocols for wireless infrared communications and the name "IrDA" also refers to that set of protocols. The main reason for using IrDA had been wireless data transfer over the “last one meter” using point and shoot principles. Thus, it has been implemented in portable devices such as mobile phones, laptops, cameras, printers, medical devices. Main characteristics of this kind of wireless optical communication is physically secure data transfer, Line-of-Sight ( LOS ) and very low bit error rate ( BER ) that makes it very efficient. Abstract: This application note describes a simple circuit allowing a PC to communicate via an IrDA-specified optical data port. The circuit employs only two integrated circuits (ICs), an external infrared...