Michael Kellett's Blog

  • A low cost fast pulse VI Plotter.

    michaelkellett
    A low-cost VI PlotterI’m currently working on a project that uses custom made LEDs emitting at an unusual wavelength. One of the most important characteristics is the current against voltage curve. This is hard to measure because the chip is tiny and...

  • Implementing a CRC on an ST micro

    michaelkellett
    This blog is about implementing an 8 bit CRC on an STM32G071xx micro. Several other ST micros have the same CRC hardware system so it will apply directly to them. There is also some discussion of CRC in general. Pretty much all this stuff is on the w...

  • Frequency Response Analyser - Power Amplifier

    michaelkellett
    I did a preliminary blog about this on May24th and promised more when I got the boards. It's a bit of a mixed story some good news, and some less good. I'm posting the LTSpice model and the schematic again , to avoid endless cross referr...

  • Frequency Response Analyser Progress

    michaelkellett
    I first blogged about this project in March. Seems quite while ago now but I have found some time to work on it.The main boards have been made and assembled.Mostly it works OK, (and one has been used to solve an entirely different problem for a custo...

  • Hiland Power Supply Testing

    michaelkellett
    23/03/2020 This project was sparked off by John's blog:One of My Favorite Building BlocksI've been thinking about power supply designs and read John's blog just after reading the power supply project in "The Art of Electro...

  • A simple frequency response analyser

    michaelkellett
    ORIGINAL POST 10/03/202UPDATED 11/03/2020 : Filter response plot added.UPDATED 17/03/2020: Board design notes added.   This idea has been at the back of my mind for while, but got pushed to the top of the stack by a post from

  • Bench Power Supplies (Cheap)

    michaelkellett
    We seem to talk a lot about power supplies on E14 - not unreasonable - you can't do much electronics without a decent bench power supply. You can buy a new single channel 30V 5A sort of thing for about £50 - and if cash is tight and your app...

  • Digital Filtering

    michaelkellett
    I've just been testing a design that includes 8 hybrid (ie mixed analogue and digital) lock in amplifiers. They aren't, strictly speaking, lock in amps because they are synchronised to an internally generated signal which dives a laser. There...

  • Fast Test Amplifier - Part 1

    michaelkellett
    A while ago (July 5th) in the discussion https://www.element14.com/community/message/241748/l/programmable-frequency-generator#241748  I suggested an approach to building a low cost high frequency power amplifier.The idea was to keep the de...

  • Solar cell energy harvesting

    michaelkellett
    We see lots of questions on E14 about energy harvesting. This link is to a nice article from Analog Devices, mainly about using once of their chips for very low power solar cell applications, but the article make some interesting background poin...

  • Fun Weekend

    michaelkellett
    I've spent most of this weekend (about 14 hours of it) soldering 3 of these. It's an industrial 24V IO board for a client with Ethernet interface. 14 of the pins are programmable input, output, pull up/down, adjustable thresholds etc. I'v...

  • It's Ethernet Jim, but not as we know it.

    michaelkellett
     This is my Ethernet switch board with 3 port Micrel switch, STM32F427 processor, real time clock and LCD display. (Totally open source hardware - copy as much as you like - I will publish Gerbers and other stuff on 26/09/2015) If you want ...