mV Meter Battery and Protection Mod
The ATmega328-based millivolt meter based on a design by Scullcom Hobby Electronics has been serving well on my bench. But time for a couple of mods:
- adding a 9V internal battery that can be used when not connected to external supply - great for when the bench is crowded
- simple reverse-polarity protection (inline rectifier), particularly to avoid any confusion over centre-negative/centre-positive power connectors
As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub
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LEAP#405 Bootloaders and Arduino Serial Programming
The Arduino IDE makes programming AVR-based microcontrollers so easy that many quite simple concepts get lost in the fog. I confess to having been hazy for the longest time concerning the role of the bootloader and what exactly was going on when you click the “Upload Sketch” button. There are actually some great resources around the net and on YouTube, but they can also mislead a little because they might focus on just one aspect, so I decided to try and pull together a comprehensive soup-to-nuts story. It covers:
- How to check what bootloader (if any) is on a chip
- What bootloaders are available?
- How to burn a bootloader with the Arduino IDE
- How to burn a bootloader with Nick Gammon’s incredibly useful Arduino utility sketches
- Breadboard Setup for Programming over USB-Serial (FTDI and CH340 veriants)
- Programming over USB-Serial with the Arduino IDE
- Programming over USB-Serial with avrdude and gcc toolchain
As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub
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LEAP#404 The Arza-matron
I’ve had the other half of the guitar I used for The Fretboard (LEAP#018) sitting on a shelf ever since. It’s almost been thrown out a number of times, but luckily I didn’t as it proved to be inspiration for this last-minute idea for a party decoration.
The basic idea, using as many on-hand parts as possible:
- sound input
- 2 LED strip circuits independently controlled and powered from 12V
- simple Arduino sketch to sample the sound and drive the LED strips with PWM
It worked just fine, although in the process I discovered the sound module I used did not output continuous reading but rather a threshold trigger (so the effect was not as subtle as I planned). Something to fix next time I want to fire this up…
As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub
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LEAP#402 Rolling with the BoldportClub Pips
The BoldportClub Pips circuit is based on “Dicing with LEDs” by Elektor (December 2006), but with a new PCB designed as only Boldport can (and a flashy red baggie).
The ripple counter toggles through all die states at around 8.8kHz. Diode steering is used to light the appropriate LEDs for each state and reset the count when it gets to “7”. This runs fast enough that it appears all LEDs are on at the same time. hen the button is pressed, the counter stops - this is a “roll”.
This is a similar concept (but quite a different implementation) to the LEAP#229 Dice project, which uses a 555 and CD4017 to also achieve a slow-down effect.
As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub
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