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Measuring Inductance or Capacitance without an LCR-meter
You have a DIY inductor and no LCR-meter at hand? – No problem. A known resistor in series, and some calculations make the day. L = R * sqrt(3) / ( 2 * π * f ) Example Measurements: * R1 = 99.82 Ω * Vout = Vin / 2 at 901 khz ( 901,000 Hz…
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Free KiCad schematic for a BJT based LC Colpitts Oscillator, 5 – 8 MHz
This oscillator is based on two transistors. No crystals, by purpose. It can oscillate on various frequencies between 4.8 MHz and 8 MHz. With a variable capacitor (around 15 – 400 pF) instead of C2, you can dynamically vary the frequency in parts of that range. Its functionlity is verified by real world build and…
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16 pF to 650 pF DIY variable capacitor
16 pF to 650 pF DIY variable capacitor from ordinary aluminium foil (alufoil), A4 paper and a cardboard tube from an empty alufoil package. Roll one round of alufoil on the blank cardboard tube. Fix it with tape. Leave 5 cm / 2 inch free from alufoil at one end. Roll a A4 paper around,…