Switchmode laser diode driver based on LT1683

Here’s a quick project I made in couple days or so. It is a push-pull step-down laser diode driver based on LT1683 SMPS controller chip from Linear Technology. The circuit works with 12-18V input and can put out about 1A to a 2V load. I used a PL140-105L planar ferrite transformer from Coilcraft which is quite overkill for this application (it is rated for 140W).

Switchmode laser diode driver based on LT1683

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High Voltage Power Supply for Nixie Tube Projects

This project is a HVPSU (High-Voltage Power Supply) that generates up to 220V from a 12V input. In addition to that, it also provides 2*Vout (so, up to 440V, for dekatrons), and two outputs for powering digital logic: 5V and 3.3V. The primary HV boost circuit reaches 88% efficiency when going from 12V to 185V at 55mA, with a 3% output ripple.

High Voltage Power Supply for Nixie Tube Projects

I designed it because I couldn’t find anything that would make sense for my Nixie projects. There are plenty of tiny power supply modules available on eBay, but most of them end up being impractical: no 3.3V (for my microcontroller) and 5V (for my 74141 nixie drivers), no mounting holes, no >400V output for powering dekatrons. Some supplies make a token gesture towards practicality by sticking a 7805 on the same board, but you quickly find out that the current draw of 6×74141 is enough to require a large heat sink on a 12V-powered 7805 (one 74141 consumes 12.5mA!). This means that instead of a single-board power supply you end up routing your input power all over the place, implementing your power supply in several places.

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Some notes on electrolytic capacitors

The fine people over at FaradNet have put together an appreciable set of notes on the electrolytic capacitors that appear in almost all consumer electronics devices. Although this is a good read for those who are interested using the devices in a safe manner (and getting the most performance out of them), there is a lot of text, so I will try to summarize the two features of electrolytics that seem to be most important: polarization and frequency response.

Some notes on electrolytic capacitors
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MindBite DMM 101

uCHobby does an instruction MindBite video about Digital Multimeters (DMM). You can view the MindBite here. In this short article I describe the new MindBite service and how I constructed a camera stand by modifying an old swing arm desk lamp.

MindBite DMM 101

MindBites is a new community service that should be very popular with the Maker crowd. The site offers Hot-To videos that are uploaded by users. Some of the videos are free but most cost a bit more then a dollar to view. You can upload your own instruction video and when it’s viewed MindBites pays you $1.

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DC booster for your 12V load

This 12V DC booster circuit uses the MC34063A device which contains all the primary functions required for DC−to−DC converters. It has a built-in temperature compensated reference, comparator, controlled duty cycle oscillator with an active current limit circuit, driver and high current output switch. It operates from 3.0 to 40.0V DC and can supply output current up to 1.5A. This booster can thus power your 12V load with a 3.7V Li-Ion battery.

DC booster for your 12V load

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LiPo Booster

LiPo Booster is a breadboard-friendly boost converter board based on the TPS61230 IC from Texas Instrument. It has an output voltage of 5V, and is designed to be used with a single cell LiPo battery.

LiPo Booster

For normal and half size breadboards, the LiPo Booster can be plugged into the power rails without blocking the vertical 5-pin strips. It can also be used with a tiny breadboard or breadboard of any sizes as shown below.

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DS3232 clock frequency calibration

DS3232 is an extremely accurate RTC with a guaranteed accuracy of 2.5 ppm (0 °C to 40 °C), which translates into an error of just 80 seconds over the course of a year under the worst case scenario. I had done a few projects using this chip before (you can read about them here).

DS3232 clock frequency calibration

While by default DS3232 is already very accurate, we can push its accuracy even higher by adjusting its aging offset register (8bit). This adjustment works by adding or subtracting the corresponding capacitance to or from the oscillator capacitor array. The adjustable range is represented as 2′s complement (-128 to 127) and each LSB change corresponds to roughly 0.1 ppm of change in frequency. So the overall adjustment range can be achieved programmatically is roughly ±13 ppm.

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