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AF Oscillators |
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Multivibrator |
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Yes, I admit: this is my favorite oscillator! A very known and easy-to-made device to every ham but too less exploited to the real possibilities. Works in a wide range of audio spectrum, and not only, at a wide range of supply tensions, from 1.2 V to 24 V (accidental, hi, and still works!). The input is very low, a few mA.
The audio range for the schema's values is from 150 to 15000 Hz, square-wave. The output signal is picked from a collector of a transistor through a capacitor.
Applications: side tone oscillator (for CW training), AF generator, tester for speakers and headphones, shortcircuit detector, etc. |
The signal frequency is:
 | The frequency is in Hz for:
R = R1+P1 = R2+P2 (W)
and
C = C1 = C2 (F) |
The PCB dimensions are 20 x 35 mm. Enclose it in a old handy receiver cassette. Put on it a connector for battery, one for external supply, a little speaker, some hubs for keyer and audio traductors and a 3 x 2 switch. |
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Nice and mini: 20 x 35 mm | 
External view |
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NAND Oscillator | E555 | Sine-wave |
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| | YO4RLP 16 februarie 2003 |
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