The main topics presented
1. Voice recorder with ISD processor family
Kit made by Conex Electronic, which uses the voice processor ISD1416 (or ISD2560 / ISD2575 / ISD2590 / ISD25120 / ISD1420), for analog recording of voice signals.
Mounting is recommended to be used in signaling systems with voice warning, automatic warnings in shops or any other public space, as well as various games or electronic montages for entertainment.
Examples include: apartment bells with voice announcement and / or robot message recording by pressing a button, car warning systems for fastening seat belts when starting on the spot, warning systems correlated with perimeter sensors or movement, warning systems for schools, museums, places of entertainment, etc.
At the base of the assembly is a specialized voice processor from the ISD family, produced by Information Storage Devices, the first manufacturer to propose a wide range of integrated circuits that can operate on the same principle as a cassette player (analog recording of voice messages)! The message is stored in non-volatile memory without being "digitized" or compressed.
Analog storage allows you to get natural sound, which cannot be obtained digitally. Editing allows recording and then playback via a memories that can store recorded messages for 100 years.
The registration cycles provided by the manufacturer in the catalog data are approx. 100.000. The maximum recording time is 16 seconds for the mode equipped with ISD1416 and 1 minute for the one equipped with ISD2560.
In the case of the voice processor ISD1416 4 different messages can be recorded, lasting 4 seconds each or a message of 16 seconds.
2. Applications of Simple Switches regulators - LM257x
Simple Switchers, a National Semiconductor brand, are a family of integrated switching voltage regulators (covering current range 0… 3A), made as a "replica" to the family of linear integrated regulators with three terminals, respectively LM78xx or LM317.
The very small number of external components in applications mainly characterizes them.
Switching source 1.2-35V / 3Amax
The source (figure 1 in the article) was tested by the author with very good results, it finally presenting the character of "universality" for the entire range of LM257x circuits.
The designed wiring can be used without modifications for various configurations of output or input voltages, sources in fixed or adjustable voltage switching (by simply removing some components).
3. Digital capacitance meter
There are many types of capaciters in the literature, which at the most recent circuit 555 timer it is ubiquitous.
Basically, these capacitances consist of an RC oscillator whose generated frequency is dictated by the capacitance value of the capacitor under test, measuring by some method the signal frequency, to determine the capacitance value.
Children this type of capacitance is nothing more than a capacity-frequency converter.
For the assembly presented without being complicated, but using modem components, the range of measured values is large; from pF capacities to capacities of hundreds of microfarads. The value of the measured capacity is read on a 3-digit display, known in the literature "Counter Display".
The main element in the counter is the integrated circuit MC14553 which is a three-digit BCD counter. Associated with it is a BCD decoder for 7 segments, the circuit MC14543 and so the display can show between 000 and 999.
4. Intelligent relay controlled by PC
The presented application allows the remote control of a relay, at the moment of occurrence of a scheduled event or by direct control of the user. The relay module can be operated and set via a computer graphical interface.
It is often necessary to remotely control certain equipment via a PC, such as turning on and off computer-connected audio equipment (for example, a music player).
The proposed application simply solves this problem, with a minimum number of components, based on the 8-bit general purpose microcontroller. PIC16F628A.
It commands a relay based on a scheduled or user-produced event. The communication of the "relay module" with the PC is made through an RS232 serial port at a speed of 9600 baud, full duplex. The user interface is simple, with various facilities for easing orders.
5. Tuning indicator for MF-UUS receivers
The presented installation facilitates the correct tuning on the frequency of a broadcasting station that does not have the automatic frequency control (CAF) function received.
If we are in possession of an ultra-shortwave radio receiver with frequency modulation, and the device is not provided with automatic frequency control (CAF), this adapter is very useful when we want to tune correctly to the frequency of the received radio station.
6. Fast and ultra-fast diodes
Fast and ultra-fast diodes are most often found in switching voltage sources in electronic devices or deflection and video floors in TV and in any other electronic (control) modules in which it is necessary to switch current and high frequency signals, they characterized by small switching times (direct and reverse-return), of the order of tens of nanoseconds.
In applications they should not be confused and / or replaced (reciprocally!) With Schottky diodes.
7. Parallel programmer for FUSE and LOCK bits at ATmega
Programming the ATmega CPU using the program Ponyprog it can "lock" these components, making them impossible to reprogram with a serial programmer (SPI).
A parallel master-slave programmer with the help of which "spindle" and "lock" bits can be reconfigured, thus allowing the "unlocking" of these microcontrollers is shown, with exemplification for the ATmega8 uC.
8. IrDa interface (IR port for PC)
Many of the motherboards that equip current or older PCs have an IR communication port connector.
The construction of an interlet was proposed by Oliver Tscherwitschke pe www.electronics-lab.com and tested on a motherboard Asus p / i-p55t2p4.
The interface is based on the circuit TFDS4500 (or TFDU4100 and this presented in the past in the magazine). 4 pins are required for the connection with the motherboard: txd, rxd (communication pins), + 5V and GND (power supply).
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