Posts

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  Free KiCad schematic for a BJT based LC Colpitts Oscillator, 5 – 8 MHz

  Jun 27, 2026

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  by

  Andrew

  in Builds, DIY, KiCad Files, Schematic

  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

  Jun 27, 2026

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  by

  Andrew

  in Builds, DIY

  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,…

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  How to wind a perfect DIY inductor

  Jun 27, 2026

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  by

  Andrew

  in DIY

  Take something of a fitting diameter that is as smooth as the side of a full, unopened soda can. Wrap a double layer of printer paper on it. Once bent, for instance. Fix it with tape as a tube, but let it be just about slidable over the can. This layer is helpful in many…