Archive for the ‘Data Communication’ Category
PC (Audio) Signal Generator Using RS232 Port
Using an RS232 port, we can generate square wave oscillation when transmitting data, and this can be “misused” as signal generator (square wave generator). This is a PC Signal generator produce a square wave in audible frequency range. This circuit utilize a transmission of a “U” character from ASCII character set. This character has binary …[Read More]
Missing Pulse Detector Circuit with 555 IC
Missing pulse detector will receive a source of repetitive pulse in normal condition. The output of this detector circuit will be inactive for normal condition (output pin 3 of 555 IC will be high, turning off the LED indication). If now the input pulse is missing, delayed, or stopped, then the output of this detector …[Read More]
Interfacing high power load can be done in many ways, such as using voltage divider resistors, transformer, or optocoupler. In the circuit shown below , an optocoupler method is presented. This optocoupler serve the logic level translation with flexible input, accepting wide range of voltage level, which is suitable for many high power load/devices. To …[Read More]
Three Wire RS232 To RS485 Converter
The schematic diagram below show the circuit diagram of an RS232 to RS485 converter circuit. The EIA-485 standard, a.k.a TIA/EIA-485 or RS-485, is a physical layer standard defining the electrical properties of electronic drivers and receivers using balanced digital signal which is capable of handling multipoint systems. The ANSI Telecommunications Industry Association/Electronic Industries Alliance …
30-Khz Bandwidth High Linearity Opto-Isolated Amplifier
Using optocoupler to directly transfer a linear (analog) voltage would produce a large unpredictable linearity error, which is also sensitive to temperature changes. By using frequency modulation, the total system’s linearity will depend only on the linearity of the V/F and F/V converter, which is fortunately cancel each other if we use similar devices with …[Read More]
Pulse Width to Analog Voltage Demodulator
This is a schematic diagram of a pulse width to analog demodulator circuit. This circuit is used to demodulate the pulse width to analog voltage level. With input pulse width range of 0 to 1 microsecond, this circuit can produces Output range of 0 to 10 v. The input pulse is integrated and the final …[Read More]
Touch Switch Data Input Interface
This is an interface circuit for digital data input. This circuit consist of touch button, op-amp, diode, capacitor and resistors. Any conductor surface can be used as the touch probe, such as a machine-screw head having comparable area around 0.5-inch-square or similar area of any pattern on printed-circuit board. This circuit need a DC power …[Read More]
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