452
Item nr.
Pocket construction kit.
Production | The Netherlands, 2016.
Price was 4.01€. |
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Bands | MW (525-1605kHz), TV/FM (76-108MHz). |
Semi- conductors | CD9088 (FM tuner), TA7642 (AM tuner), TDA2822M (AF amp), LED. |
Cabinet | Plastic. Size 10x6,5x2,5cm. Weight 73gr. |
Power | Batt 2xAA. |
Documents | Schema. |
If you ever want to construct an AM receiver with the TA7642 IC, please take a look at the power supply of the 7642 here. The 7642 needs about 1.3V and draws 0.3mA, so one might be inclined to place a series resistor of 4k7 between the battery and the IC. Bad thing would be, that the entire series resistor would be "visible" for the AGC current flowing through the IC, resulting in an overly strong AGC operation. The ZN414 technical notes suggest a so-called "diode drive", where the supply voltage is kept constant by running excess current through conducting diodes. In that respect, this schema contains the diode drive, with the LED functioning as voltage stabilizer for the 7642.
Obtained | 3/2017 from Aliexpress.com. |
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Condition | 7. |
Disposed | Scrapped 3/2021. |
Sound sample | PLAY SOUND The quality of the receiver is very suitable for 19th century sounds. |