When an LED torch can kill

I've received one of those (supposedly) Chinese powerful LED torches from my brother. To be precise, this one: I was not expecting too much from it, it's awesome and does a lot of light and the like. But I do not want to praise it, rather I got very suspicious when I've discovered that contains …

MC34063, the jellybean converter (Part 1) – Introduction design of a voltage inverter

When I needed to design a dual power supply I was looking for parts capable to handle buck, buck-boost, with inverting and non inverting properties. Because I was also looking for a contained budget, I've been fascinated by a single, multipurpose part, capable of doing all of this. I immediately realized it was the 555 …

Experiments in implementing the WS2812B protocol in AVR MCUs without bit-banging

I started to experiment with the WS2812 LED, more specifically the WS2812B, which is a better revision in term of connections. These are the very famous individually addressable RGB LED, where tons of sources are available. Mainly due to their low cost, they are spread to the maker scene like a rhinovirus in a primary …

AOC I2475PXQU LCD monitor – teardown and repair

One of few repairs that went smooth and succesful. Using a monitor with integrated USB hub can be useful, but also tricky, if such hubs are designed in a cheap way or is not fool proof, and I am a fool. If that is the case, overloading the output lead to a dead port. And …

Switching converters nostalgia: a brief history

I have some kind of interest in electronic projects, whether hobbists or a professional ones, which are based on standard and always available sub-components. Those always available parts are also called jelly bean components, like resistors, capacitors and cheap basic parts, like op amps (including in my opinion also LM741, LM324, even TL081 and the …

Glighter-A driver LED – The mixed signal control

It was not long time ago in which was developed a small DC-DC LED driver - Glighter-S, my first switching LED driver. It was the natural consequence of the need for efficiency after the development experiment of the linear LED driver - Glighter. No long time after these experiments, the need for analog control in …

Dimming LEDs (part 3/3) – The overlooked boundaries

In the last PWM discussion, we devised how is composed the average current, specially when the PWM frequency is faster than it should be, making the period duration comparable with the rise and fall slopes duration of the current. The results were packed up in 2 equations to summarize what is the best choice for …

Dimming LEDs (part 2/3) – Sneaky non-linear events while using the PWM technique

In the previous article we tried to analyze what is the Contrast Ratio in a LED driver and how the non-idealities are giving a boundary on the minimum allowable PWM period. That was quite worth a full article, but a big part was indeed missing. Here we will go through how the PWM period and …

Dimming LEDs (part 1/3) – Analog and digital, not analog vs. digital

While messing around with dimmable DC-DC converters for LED drivers, I had the need to quantify the contrast ratio of a dimmable light. Turns out it is not that trivial, specially when combining switching periods, transients and mixed analog/PWM dimming. Looking for contrast ratio on the internet is only useful if you want to buy a TV, not if you want to build a LED driver. Also, on the web not all information seems to be correct, therefore this article and its possible continuation is the result of long investigations and discussions between engineers.

NTC Measurements (part 2/2)

In the previous NTC Measurements article, was shown the basic approaches and few variations of them in order to use an NTC, by following the suggestions provided in the datasheet and taking the correct assumptions in all the temperature signal processing. These suggestions are usually not  provided,  because with a  bit of math a lot …