1. TDA1904, TDA1905, TDA 1908 and TDA1910 audio amplifiers
The integrated circuits TDA1904, TDA1905, TDA1908 and TDA1910 represent relatively low power (audio frequency) amplifiers of relatively low power, respectively 4W, 5W, 8W and 10W, on loads between 4 Ohm and 16 Ohm. These are produced by STMicroelectronics (formerly SGS - Thomson) and although they are among the first specialized integrated audio amplifiers and therefore offer neither the powers nor the other facilities presented by the latest types of such ICs, they are still widely used and, therefore, we believe that it is worth reviewing, in short,…
2. HI-FI tone corrector
For the fine tuning, according to preferences, of the sound hodograph, typical of an audio music program, translated by the preferential correction of the output amplitude-frequency characteristic, an electronic block called universally, tone corrector, is always inserted after the preamplifier floor.
In this way, the musical listening is improved, according to the listener's preferences, by accentuating or deactivating some portions of the audio tape in which the sound music program is framed.
According to these considerations, any audio frequency amplifier is preceded by a simpler or more complex tone corrector, depending on the final general performances that are to be obtained in the field.
3. Repeater without filter
Where it is possible to mount the reception unit separately from the transmission unit, at a distance of at least 200m, a voice repeater can be built without the use of filters. The connection between them can be made by means of stations in another band or by cable.
4. Wobbling circuit
With the help of this assembly, the amplitude characteristics of some tuned circuits or of some AFI chains in the frequency range 100 - 500 kHz can be visualized on the screen of an oscilloscope. You can also see the "S" curves of some discriminators with central frequency in the same frequency range.
5. LED strobe
The existence of LEDs with large diameter and very high brightness allows the realization of a simple stroboscope.
The assembly proposed in the adjacent diagram makes it possible to observe the rotational movement of the different mechanisms (the axis of a drilling machine, the turntable of a pick-up, the transmission wheels from the car engines, etc.). Due to the high brightness of the LEDs, observations can be made in ambient light, but not in full sun…
6. Device for limiting idling
The device for limiting idling is an electronic device and was made for the rotary welding groups CS3 - CS5 (315A - 500A) in order to disconnect the drive motor from the mains, when a relatively long time passes between two welding operations. , during which the drive motor consumes electricity unjustifiably.
The device is an energy saver. In addition, through the stops it makes, it reduces the number of hours of effective operation of the group, which leads to a decrease in wear (for example: collector brushes, collectors, bearings, etc.).
7. Electronic control for stepper motors
It presents an electronic scheme for operating stepper motors (MPP) that can be implemented more easily, being composed of integrated circuits and discrete elements more easily accessible.
8. Programmer for microcontrollers AT89C1051 / AT89C2051, AR89C51 / AT89C52
The AT89C series microcontrollers operate at low voltage (+ 5V), with low power consumption, being made in CMOS technology. These components are manufactured by Amtel and are compatible, as an instruction set, with the MCS-51 industry standard. By combining in a single integrated, an 8-bit central processing unit and a Flash memory, a powerful microcontroller is obtained, which is a flexible solution, with a low cost, for a series of applications.
