my recent reads..

LEAP#231 LED Dimmer (current regulator)

I was looking at some alternatives for dimming a 12V LED strip. This circuit is by Jim Keith at electroschematics. Rather than using PWM, this circuit controls the current and provides better flicker-free lighting even when dimmed. Very nice! hero_image As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub


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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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