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

Probe Compensation on the Analog Discovery BNC Adapter Board  [draft]

When I got my Analog Discovery 3, I made the decision to also purchase the BNC adapter board. Trying it out with some OWON scope probes I got from Amazon, it unfortunately didn’t cut the mustard. This was the most square I could get by twiddling with the compensation adjustment. To prove that I haven’t goofed it somehow, this is at the opposite end of the compensation range: This waveform ain’t even square at this point....

November 3, 2023 · 2 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

Analog Discovery 3 Usage Notes  [draft]

Why I bought it in the first place The Analog Discovery 3 seemed like a band-aid solution to an ongoing problem I have been facing here at Cambridge: how do I get my own oscilloscope so that I can get back in to doing electronics without having to rely on the few shared scopes at the Dyson Center (the Dyson Center is sort of like a makerspace for engineering students, it isn’t great though…)...

November 1, 2023 · 2 min · Infinus

Inline Microphone Preamp Update 1: KiCad Footprint Trap

So here’s the situation, I accidentally ordered the parts for the Inline Microphone Preamp Project … to Malaysia. One month and a trip to Portugal later, I finally got the chance to use the electronics lab here in Cambridge for the first time to asesemble this thing (thanks Elena for bringing the stuff over for me!), and in good old DIY analog electronics fashion, it didn’t work first time. Turns out, the SOT-89 footprint in KiCad has it’s pins in the opposite order from those in the NXP datasheet for the PBSS4540X and PBSS5540X transistors I was using....

April 27, 2022 · 3 min · Infinus

How to Embed SVG Schematics from KiCad into a Hugo Page

I have recently decided to move Infinus Electronics over to Hugo, as WordPress with its weird styling issues and super hard to understand file structure made it way too frustrating to debug and customise. So far, working with Hugo has been a blast, and having worked with frameworks like Laravel and Flask before, the whole organisation of pages by file hierarchy has been a lot more intuitive. And transparent. The issue My first post written on this new platform is the Battery Powered +48V Phantom Power Supply , which of course, had to show a schematic from KiCad....

December 25, 2021 · 7 min · Infinus