A simple project, within most of homebrewers capabilities. Very simple tuning, a single stage to align, besides VFO frequency adjusting. Easy to find, cheap components. Reduced dimensions and low power requirement, a totally portable rig. It's worth while to spend some words about the DSB modulation. It's simply a type of amplitude modulation (AM). It is common knowledge that an AM signal is composed by a carrier and two sidebands, wich take the whole information. The figure below represents an AM signal at 14.000 KHz, modulated with a 5 KHz bandwide BF signal.
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The receiver is a direct conversion unit. It is composed by a double tuned preselector, equipped with a
BF965 mosfet, delivering a 10 dB gain, and a product detector using a "classic" NE602
(further 18 dB of
gain). A variable capacitor C4 allows to adjust the sensitivity according to the connected antenna, so we may
find a right compromise to limit the effects of the strong broadcastings operating at the band edges. The
detected audio is amplified by a 2N2222 transistor and an LM386
IC delivering a few hundreds mW into
an 8 Ohm speaker.
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
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This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
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