Category Archives: comparator

The Pros and Cons of Microcontrollers for Boost Converters

It never fails — we post a somewhat simple project using a microcontroller and someone points out that it could have been accomplished better with a 555 timer or discrete transistors or even a couple of vacuum tubes. We welcome the critiques, of course; after all, thoughtful feedback is the point of the comment section. Sometimes the anti-Arduino crowd has a point, but as [Great Scott!] demonstrates with this microcontroller-less boost converter, other times it just makes sense to code your way out of a problem.

Built mainly as a comeback to naysayers on his original boost-converter circuit, which relied …read more

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Posted in boost converter, comparator, dc-dc, microcontroller, Microcontrollers, misc hacks, mosfet, op-amp, switch mode power supply, SWMP | Leave a comment

Scrap a Hard Drive, Build a Rotary Encoder

There’s something to be said for the feel of controls. Whether it’s the satisfying snap of a high-quality switch or the buttery touch of the pots on an expensive amplifier, the tactile experience of the controls you interact with says a lot about a device.

[GreatScott!] knows this, and rather than put up with the bump and grind of a cheap rotary encoder, he decided to find an alternative. He ended up exploring hard drive motors as encoders, and while the results aren’t exactly high resolution, he may be onto something. Starting with a teardown of some old HDDs — …read more

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Posted in BLDC, coil, comparator, encoder, hardware, hdd, MCP6002, windings, wye | Leave a comment

Junkbox Freezer Alarm Keeps Steaks Safe

A fully stocked freezer can be a blessing, but it’s also a disaster waiting to happen. Depending on your tastes, there could be hundreds of dollars worth of food in there, and the only thing between it and the landfill is an uninterrupted supply of electricity. Keep the freezer in an out-of-the-way spot and your food is at even greater risk.

Mitigating that risk is the job of this junkbox power failure alarm. [Derek]’s freezer is in the garage, where GFCI outlets are mandated by code. We’ve covered circuit protection before, including GFCIs, and while they can save a life, …read more

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Posted in 555, alarm, comparator, current transformer, ferrite, freezer, fridge, GFCI, GFI, home hacks, magnet wire, peak detector, refrrigerator | Leave a comment

The Right Circuit Turns Doppler Module into a Sensor

Can you buy a working radar module for $12? As it turns out, you can. But can you make it output useful information? According to [Mathieu], the answer is also yes, but only if you ignore the datasheet circuit and build this amplification circuit for your dirt cheap Doppler module.

The module in question is a CDM324 24-GHz board that’s currently listing for $12 on Amazon. It’s the K-band cousin of the X-band HB100 used by [Mathieu] in a project we covered a few years back, but thanks to the shorter wavelength the module is much smaller — just an …read more

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Posted in band pass filter, comparator, Doppler, high pass filter, misc hacks, op-amp, radar, radio hacks, sensor, speed, velocity | Leave a comment

Saturday Clock: An 0.000011574Hz ATtiny85 clock

In these times when we try to squeeze out extra clock cycles by adding more cores to our CPUs and by enlisting the aid of GPUs, [Ido Gendel] thought it would be fun to go in the exact opposite direction, supply a clock to the ATtiny85 that cycles only once per day, or at 0.000011574Hz. What application could this have? Well, if he could do it in seven instructions or less, how about turning on an LED at sunset Friday evening, to indicate the start of the Jewish Shabbat (Saturday), and turn it off again at sunset Saturday evening.

Notice …read more

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Posted in ATtiny Hacks, attiny85, clock source, comparator, custom clock | Leave a comment