Jan 16, 2017 Electronics LED PWM 555

LEAP#232 LED Dimmer PWM

In LEAP#231 I claimed current control was better than PWM especially for flicker-free low light levels. But is that true? In this project I test a simple 555 Timer-based PWM dimmer for comparison’s sake. As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub

And yes, of course it flickers. Whether that is noticable or annoying depends on the frequency.

Now perhaps some flicker might be a Very Good Thing, if the research discussed in this RadioLab episode bears up in practice. But flicker should still be something you explicitly design to have or eliminate.

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Jan 15, 2017 Electronics LED Power

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! As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub

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Jan 10, 2017 Electronics LC Oscillators

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

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Jan 9, 2017 Electronics 555 4017

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

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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