August 2007 - Do It Easy With ScienceProg

DIY USB to RS232 adapter

Sometimes you need to connect some device to a COM port, but the computer doesn’t have one, especially a laptop. There are two ways – go and buy a USB to COM adapter or build one. So if you decided to build a USB to COM(RS232) adapter, there is one solution. This adapter is straightforward to build as there is a single-chip USB to UART bridge (CP2102). This chip from Silicon Labs supports USB2.0 full speed. Internal Resistors are required for the USB interface, integrated clock, internal 1024 -byte EEPROM for Vendor ID, Product ID serial number, power descriptor, and other information. SP2102 USART part support almost all standard features of RS232 communication including handshaking, Databits (5, 6, 7, and 8); 1 or 2 stop bits; odd, even, mark, space, and no parities; baud rate from 300bps to 1Mbits.

Facts about melanoma you should know

Oscilloscope probes for accurate signal measurements

Oscilloscope Probes Measuring signals with oscilloscopes may be a challenging task especially high-frequency ones. Without proper oscilloscope probes, correct measurement of high-speed time-domain signals wouldn’t be possible. For high-speed measurement, you should consider signal parameters like amplitude, source impedance, rise time and bandwidth. There is a wide variety of probes available – passive, active, current-measurement, optical, high voltage, and differential. But let’s narrow the discussion to probes used to measure signals with wide bandwidth and short rise times. There are also many variations on what probe is proper. As probes are potential load to measured circuits, it is important to know their sensitivity to resistive, capacitive, or inductive loading. Incorrectly chosen probes (like high capacitance) can distort the fast-rising signal. Some circuits may not tolerate probes at all (high-speed amplifiers).

AVR based TDA7313 Audio processor control

TDA7313 audio processor has been used for more than ten years because of its simplicity, functionality, and proper parameters like low distortion and low noise. Chip is based on BIPOLAR/CMOS technology and can be used in various applications, including car radios, Hi-FI, simple mixers. TDA7313 chip has three external stereo inputs that allow multiplexing three incoming sound sources. It has a volume control with steps of 1.25dB, Treble and BASS control, Loudness function. Each of the four outputs has a distinct control that allows balancing outputs. A chip can be controlled via an I2C (TWI) interface. Description of Audio processor This project’s idea was to construct an independent audio processor that can be embedded in any sound system with the ability to control settings with a simple button interface with a menu preview in LCD. The intent was to cover all audio-processor functionality within the LCD menu.

Simulate KS0108 graphical LCD with Proteus simulator

Today it is common practice to use various circuit and microcontroller simulators for developing programs. Using simulators, you have several benefits comparing to real prototype boards. You don’t have to connect any hardware to test a piece of code; also, you don’t have to be in the same place when working. You can have simulator software on your Laptop and work where ever you want. Of course, you can see more parameters within the simulator like register values, memory, signals in a convenient form. So controlling graphical LCD on simulator software like Proteus is an easy task.

Reliable soldering with fluxes

Reliable soldering can be achieved by soldering clean surfaces. Usually, surfaces are cleaned with abrasives and solvents, but after the surface is cleaned surface immediately oxides, especially when heated. During oxidation, the surface is covered by thin oxide film, which prevents solder from contacting metal. This is why flux is used in the soldering process. To remove/deoxidize, surface flux must be applied during soldering. Flux chemically removes surface oxide when heated and makes a good metal to solder contact. There are several categories of soldering fluxes: Acid Flux (or commonly known fluxes: Zinc chloride, hydrochloric, ammoniac); Organic Flux; Rosin Flux. Each flux has its own specifics and may be used for different soldering technologies.