Constant On Time LED Dimmer

Introduction The world of digitally controlled switchmode power supplies has always held a certain allure for me: the idea that you could sample things like output voltage and current, apply some DSP techniques, and then based on that output a gate drive signal in real time, giving you whatever response you want out of your buck/boost converter just seems so… insanely cool. That being said, a lot of times these require a good understanding of the control loop architecture and parameters of switchmode power supplies to be able to properly stabilize, which has proven to be quite the barrier to entry....

January 25, 2024 · 12 min · Infinus

Analog Discovery 3 Front End Amplifier MK3

Introduction I started off this project when I realised that the official Discovery BNC adapter board has too high an input capacitance to be used with generic scope probes, which usually have a compensation range of 5-35pF ish. Using scope probes is really necessary in some cases where low loading is desireable, since the quoted 1MΩ || 24pF input impedance of the Analog Discovery 3 loads down sensitive analog circuits quite significantly....

January 24, 2024 · 7 min · Infinus

Analog Discovery 3 Front End Amplifier MK2

Before reading on, please refer to the previous part/MK1 of this project, otherwise some of the stuff here might seem a little odd. Schematic <?xml version="1.0" encoding="UTF-8" standalone="no"?> SVG Image created as AD3 Front End Amplifier-CH1.svg date 2023/12/18 09:48:42 Image generated by Eeschema-SVG C207 C207 1u 1u -2V5 -2V5 1 1 2 2 SW201 SW201 AC/DC AC/DC C203 C203 1u 1u V- V- 2 2 V+ V+ 5 5 1 1 + + 3 3 - - 4 4 U202 U202 C201 C201 10n 10n -2V5 -2V5 +2V5 +2V5 C208 C208 1u 1u R207 R207 402 402 R201 R201 1k 1k R208 R208 22 22 V- V- 2 2 V+ V+ 5 5 1 1 + + 3 3 - - 4 4 U201 U201 D201 D201 R202 R202 1M 1M C205 C205 1u 1u C204 C204 1u 1u R203 R203 100 100 R204 R204 402 402 R206 R206 402 402 +2V5 +2V5 C206 C206 1u 1u R205 R205 22 22 C202 C202 10n 10n 1 1 2 2 J201 J201 CH1 CH1 COM COM 1 1 NO NO 2 2 V- V- 3 3 IN IN 4 4 V+ V+ 5 5 IC201 IC201 TS12A4516DBVR TS12A4516DBVR OUT+ OUT+ OUT- OUT- V+ V+ V+ V+ V- V- U202 U202 V- V- 2 2 V+ V+ 5 5 1 1 + + 3 3 - - 4 4 -2V5 -2V5 SW201 SW201 AC/DC AC/DC 1 1 2 2 -2V5 -2V5 U201 U201 V- V- 2 2 V+ V+ 5 5 1 1 + + 3 3 - - 4 4 C206 C206 1u 1u IC201 IC201 TS12A4516DBVR TS12A4516DBVR COM COM 1 1 NO NO 2 2 V- V- 3 3 IN IN 4 4 V+ V+ 5 5 D201 D201 Check out the design files here Compared to the MK1 design, the gain stage is essentially identical....

December 18, 2023 · 5 min · Infinus

Analog Discovery 3 Front End Amplifier MK1

The Analog Discovery 3 is a great debugging tool, but as I discovered here in a note on using it with 10x scope probes, the input capacitance was too high for the probes to be compensated correctly. Custom LNA design To combat this, I decided to design an amplifier that would have a low input capacitance so that we fall within the 5-35pF compensation which is typical of these 10x scope probes....

November 3, 2023 · 12 min · Infinus

Winter Logger

One of the (many) weird quirks of studying in the University of Cambridge is that our terms only last 8 weeks. Yes, the number of days we are officially “studying” is less than the number of days we are ostensibly on “holiday”. Of course, it never works that way, and Cambridge is probably one of the only places where going to uni feels exactly like going to secondary school. Over these long break, we are told that our rooms are going to be used for conference purposes, and that we would have to move all our stuff out to a tiny, cramped storage container....

January 30, 2023 · 20 min · Infinus

I2C EEPROM Tester with CircuitPython on a Raspberry Pi Pico

As part of the Winter Logger project, I got myself some DIP EEPROMs from eBay which were ostensibly AT24C256’s, mostly because I didn’t feel like buying yet more stuff that I probably would never use just to pad out Mouser’s £33 for free shipping minimum order. This is what I got: Suspicious… With all the counterfeit semiconductors floating out there, I wanted to verify if I at least had functional EEPROM that wasn’t literally just plastic with some legs tacked onto it - I wanted to test if all the memory cells actually worked....

November 12, 2022 · 4 min · Infinus

Inline Microphone Preamp

This is an attempt to try to get more signal out of dynamic microphones, as I literally have to max out the gain on my Presonus AudioBox iTwo to barely get a usable signal level, and that is with me speaking right on top of the microphone. This design is based on Project 66 by Eliott Sound Products , with some minor modifications, mostly me just playing around to see what are the effects of changing stuff around....

April 28, 2022 · 1 min · Infinus

Milk Jug Patch Antenna

This is not really a “project” in and of itself. Rather it’s a small experiment that me and my buddy Chris ran to investigate two things: Just how well do the figures coming out of the Patch Antenna Calculator that I botched together translate into the real world. How does bending the patch antenna (such as conforming it around a rocket tube) affect its parameters. The antenna itself This antenna was born on a chilly Friday night, in a generic teaching room in Lucy Cavendish College here in Cambridge....

March 29, 2022 · 4 min · Infinus

Battery Powered +48V Phantom Power Supply

The good, and perhaps bad, thing about passions and hobbies is that the energy to zealously pursue them ebbs and flows as the days, weeks, months or even years go past. Just recently, I experienced a strangely strong desire to just go out there and design something again out of frusration over what we’re “learning” at university, so here we are. Preface: Why LCSC Because DigiKey/Farnell/RS wouldn’t give me free shipping until I spent tonnes of cash, and even then, the VAT here in the UK is just crazy… It’s times like this when I really, really miss being in Malaysia....

February 25, 2022 · 7 min · Infinus

ESP Practice Amplifier

This is my attempt to try building this power amplifier from Elliott Sound Products , which was specifically designed to be a practice amplifier, in the sense that it allows electronics enthusiasts like us to practice our building and bug-tracking skills, and also to try modifying the circuit to learn some analog electronics. I had a lot of fun building this amplifier and attempting to do some measurements on it, and I hope you will enjoy this slightly more lab-notes style post....

December 29, 2021 · 12 min · Infinus