Dimming LEDs (part 1/2) – 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.

Annunci

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 …

DS1307 RTC Emulator – The Arduino library

Things must come to an end. I decided to make a new library experiment, putting an ending mark to the DS1307 Real Time Clock hacking project, because the project was born as an encapsulation of a real RTC in a PIC microcontroller, wrapping an RTC hardware engine to emulate the DS1307; then a subsequent development on …

HardWire, the enhanced Arduino Wire library

I have spent a lot of time on playing and later working on the I2C buses. I almost always used self developed libraries, both for learning and job requirement purposes. Then, when experimenting with a portability of a project in the Arduino environment, I started to trying the official Wire library, discovering some incompatibilities for my …

Lino Project

I am playing with LEDs for few month and during that time some little projects were born, but now I need a system to handle the logical part and the power distribution. I simply just can't use an Arduino board, or any other development board: I need a proper power handling embedded in a small space, …

Tiny, robust, low cost, fail-safe LED driver: the Glighter-S project

It has been a while since the last LED related article. Was experimented the linear current source, its pros and cons and the field of application. Now arises the need of a small version, handling the same high power, things that are contrapposed in the linear regulator. I need something that I can bring with …

Current sources for LEDs – Glighter: a multichannel LED Driver

A power constant current source, high speed, for power LEDs. Taken all the errors made previously, I tried a new linear based current source which should be kept "simple" and "fast".

Smoked crystals (Oscillator)

Once upon a time, during a lecture about electronics, more specifically on crystal quartz oscillators, a professor said that you can break a crystal oscillator by dropping it, because the quartz inside can be broken due to the fall, even if it seems solid like a common 1/4W resistor. Let me start with a briefing …

NTC Measurements (Part 1/2)

When dealing with low-cost, home made termometers, the choice often fall on the NTCs. These sensors are resistors which are varying their resistance in function of the temperature, with a negative trend: Negative Temperature Coefficient is their name, also known as Thermistor. That means higher the temperature, lower the resistance: We observe that this cheap …

DS1307 Real Time Clock hacking: the emulation

Maybe some of you knows well the so called GertDuino, an expansion board of the RaspberryPi. It is like an Arduino which can communicate with the Rasp, and moreover it also mount an Atmega48 which can be used to emulate an RTC. Yes, I'm going to talk about this. The challenge: proof-of-concept of commercial real …