Michael Kellett's Blog

  • Measuring DC-DC converter Efficiency

    michaelkellett
    This blog is about my test rig for measuring DC-Dc converter efficiency in the range Vin/Vout 2-50V and Iin/Iout 1-10A. It can also be used to measure the power consumption of DC systems in same range. The test rig ready to run (power supply and devi...

  • Comparing noise from a linear PSU and an isolating USB adapter PSU

    michaelkellett
    Recently I blogged about a mains powered isolated dual low noise power supply I had built.  scottiebabe suggested that for some purposes it would be easier and cheaper to use a USB isolator. These can be bought quite cheaply from Amazon and very...

  • An isolated low noise +/-5V DC power supply

    michaelkellett
    Introduction I’m working on test rig for accurately measuring the efficiency of DC-DC regulators or converters. It uses 2 precision current shunts to measure the input and output current. These need very low noise pre-amplifiers which must each...

  • Silent Switcher - LT8640s meets KiCad

    michaelkellett
    The first part of this project kicked off with a blog “First Design with KiCad (8.0)” about 4 weeks ago. The idea was to build a replacement for obsolete TO3 can linear voltage regulators using the Linear Technologies (now owned by Analog...

  • First Design with KiCad (8.0)

    michaelkellett
    I’ve been using the same PCB design software for over 20 years (Easy PC) and it’s served me well during that time. It’s had an update pretty much every year and it can still load files from 20 years ago. It hardly ever crashes and I...

  • HP 3325A Synthesizer/Function Generator

    michaelkellett
    I recently bought this instrument on Ebay - it's quite an old design and if you fancy one the 3325B might be a better bet since it has a much more modern processor and a few extra functions (but will cost more). It was first released in 1979, at ...

  • Coil Winding Machine

    michaelkellett
     A while ago (October) I ordered a coil winding machine from Alliexpress. It took a while to turn up (6 weeks or so) but it was free shipping. Several vendors sell the same machine with slightly different labelling and features. The prices vary ...

  • AD8367 as a wideband true RMS detector.

    michaelkellett
    In a recent thread  ggabe mentioned using the AD8367 as a true RMS detector. I'd never encountered this chip before and was interested in what it could do. The official eval board from AD costs about £110 which is a little steep for a ...

  • A Really Simple HF True RMS detector

    michaelkellett
    In a recent thread Shabaz was wondering how easy it might be to make a wideband true RMS detector  using a surface mount thermistor and resistor. This is a first very crude and simple experiment to find out. I soldered tiny bare wires to a 10K 0...

  • Time is "cheap" - 2nd user low cost precision oscillators

    michaelkellett
    Time is cheap - Investigating low cost 2nd hand oscillators from China There have been a couple of projects and discussions about time and clocks on E14 lately: Digital Clock Episode 600: Building My Dream Digital Clock: DIY 7 Segment Display wi...

  • In Praise of Polydoh

    michaelkellett
    After seeing it recommended by  /members/shabaz I bought myself some Polydoh. It's a low melting point plastic supplied as little spheres. You put it in hot water and it goes clear and moldable. I've used it to make quick covers for pin headers....

  • Efinix Dev Board - PSRAM working

    michaelkellett
    In the last blog about this board, I talked a little about the PSRAM chips. This blog is about getting them working and some digression into memory controllers in general. I have two AP Memory APS6404 chips on the board and directly attached to the F...

  • Efinix Dev Board - setting up IO and PLL

    michaelkellett
    In the first blog of this series there is a schematic which shows the two AP Memory APS6404L Pseudo SRAMs connected to the FPGA. These can be clocked at a maximum rate of 130MHz, but there are some issues in going that fast – firstly the maximu...

  • Efinix Dev Board Running

    michaelkellett
    Having built the boards, I was determined to get one running before Christmas. It went quite well. The first tiny snag, that wasted a little time, was wondering why the 3.3V regulator (LM1117) was only outputting 3.0V. It turned out that with no load...

  • Efinix Dev Board Assembled

    michaelkellett
    The boards came from PCBCART this week. They often send a couple more than ordered but this time got carried away and sent 20 although I only ordered (and paid for) 10. It's one of the reasons that I like them. Most PCB places make extra boards t...

  • OLED display for Efinix Dev Board

    michaelkellett
    The Efinix FPGA board has a connector for an SPI interface OLED display driven by the GD32103 processor. I’ve made some little experimental display controller boards which use this processor and can run the same code as the FPGA board processor...

  • Simple Dev board for Efinix Trion FPGAs

    michaelkellett
    Die hard E14 blog readers will be familiar with my blowing the trumpet for low cost simple FPGA development work and I’m at it again. I’ve just done some work for  a client where they really wanted to use the Intel(Altera) Max 10 and...

  • Heatsinks

    michaelkellett
    Recently /members/andrewj posted about some issues with heatsinks. It so happened that he was thinking of using heatsinks similar to one I'd already chosen for a resistor based adjustable load. I'd run into some issues using active loads with...

  • 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...