Mastodawn

LB4FH Nov 23, 2025

Almost a decade after getting my #hamradio license I've started playing around with #electronics again. It's so fun when you actually make things work out properly https://www.youtube.com/watch?v=5TwWUtZ6Q3I #colpitts #oscillator #breadboard #oscilloscope

Building a Colpitts Oscillator

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Josef 'Jeff' Sipek Jan 15, 2023

The feeling when what sounded like a simple enough activity (learn how to select the right components for emitter-follower based #Colpitts crystal oscillators) leads you on a multi-day "scavenger hunt" involving far too many useless tutorials, plenty of presentations that gloss over important details, a few sources that expand on the often mentioned but rarely explained Barkhausen criterion, and currently consists of reading an IEEE workshop paper questioning BC's guarantees. #electronics

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Josef 'Jeff' Sipek Nov 26, 2022

Since #Colpitts oscillators can be built using LC tanks as well as crystals, tonight’s experiment was to replace the crystal with and LC tank. #electronics

I used jumper wires to connect a 6.4uH inductor in series with a 10uF capacitor as the “crystal”. The capacitor is needed to avoid DC shorting the transistor’s base to ground.

Josef 'Jeff' Sipek Nov 26, 2022

A couple of weeks ago I made a simple #Colpitts oscillator-based crystal tester targeting around 10MHz. Today, I decided to play with tank circuits. #electronics

First, here is the tester. After prototyping it on a breadboard, I managed to squeeze all the components onto 6 by 8 piece of protobord. The crystal is socketed. I’ve tried a variety of crystals between 3.5 and 20MHz. They all work well enough to figure out the approximate design frequency.