my recent reads..

LEAP#230 Minimal LC Oscillator

I borrowed this idea and circuit design from stoneslice’s 1MHz Oscillator video. I tested a range of components across a range of frequencies from 1.5MHz to 2.9MHz. As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub hero_image

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LEAP#229 Dice

This is my deluxe version of a 555/4017-based dice circuit. It’s got slow-down and auto power-off, but is also craftily packed into a cube. All the inards are exposed, but I think that’s a good thing. Perhaps the next step would be to cast it in clear resin? As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub hero_image

This project is a combination of circuit ideas. It breaks down into 5 main systems:

  • Counter: The 555 timer and CD4017 provided a clocked 1-of-6 line output
  • Die Display: A network of steering diodes and transistors decode the 6 outputs to a 7-LED conventional dice display
  • Counter roll & slowdown: An RC network and high-side PNP switch slow the counter speed over time until the “roll” stops
  • Auto Power-off: a p-channel MOSFET with RC timer cuts the circuit power after the roll
  • Trigger: a mercury switch simulates a “shake”

Here’s a quick video of the dice in action:


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LEAP#228 Transistor Curve Tracer

This is a fascinating circuit, originally from the IEEE Engineering Sciences & Education Journal Vol 8 No 1 Feb 1999 pp25-26. I’m working from a demonstration by w2aew. It actually builds on the basic StairStepGenerator project and adapts it to perform basic NPN BJT curve tracing - plotting collector currect to collector voltage for different base current values. hero_image It generates curves like this.. curve_2N3904_50kRb As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub


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LEAP#227 KnightRider with a 555 Timer

This is a well-known LED effects circuit using the 555 timer and 4017 decade counter. The 555 timer is configured as an astable multivibrator, with a frequancy of 10.5 Hz at ~50% duty cycle. The clock signal from the 555 drives the 4017 decade counter, providing 10 signal lines. The 10 outputs of the 4017 (Q0 to Q9) are wired to the appropriate LEDs with steering diodes to generate the “Knight-Rider” pattern hero_image As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub


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