LEAP#201 Yet Another Doorbell
aka door-fart according to my better half ... 555 Timer-based oscillators are not exactly the most musical creatures.
#201 is a kit build. Ridiculously cheap on aliexpress, it even came with extra components, so a bit of a bargain impulse-buy.
The kit turned out to be a simplified version of a circuit I've built before. It lacks the power control circuit, and draws about 4mA when idle - so if you actually use it, expect to be replacing batteries on a regular basis.
As always, all notes, schematics and code are in the Little Arduino Projects repo on GitHub.
Here's the start of the "ding.." on a 'scope..
read more and comment..
LEAP#200 Mini Solenoid Engine
Solenoid engines? They definitely fall into the the category of because you can.
Some people take it to a whole other level (like this V8 model).
What I have here is much more modest - a single-cylinder engine powering an impromptu-wire-art drive train. The mini-solenoid used here has a very small effective stroke - about 8mm - which necessarily constrains the gearing. I was inspired by 30GB's similar model for the layout.
As always, all notes, schematics and code are in the Little Arduino Projects repo on GitHub.
read more and comment..
LEAP#199 CD4026 Bucket-brigade LED driver
This is an extension if the ideas in #196, demonstrating how it's possible to build a "bucket-brigade" of CD4026 chips to drive an arbitrary number of 7-segment LEDs with a single data line.
It just requires the carry-out from the first CD4026 to be chained as the clock input for the second and so on.
As always, all notes, schematics and code are in the Little Arduino Projects repo on GitHub.
read more and comment..
LEAP#198 Hall Effect Switch
Hall-effect sensors generally support one of three modes:
- switch - turn on in the presence of a magnetic field of a specified polarity
- latch - turn on in the presence of a magnetic field, and stay on until exposed to the reverse polarity
- linear sensor - output is proportional to the magnetic field strength
The chip is rated for continuous output current of 25mA, so that is sufficient to drive an LED (as demonstrated here). For other switching applications, the output can be used to switch a transistor or pull a microcontroller output low.
Testing with some neodymium magnets, I get a strong full-on when the south pole of the magnets are within 23mm directly to the front of the chip. The output remains on until I pull back to over 40mm.
A common use for Hall-effect sensors is to detect and measure rotation. A good demonstration of this is to sequence a PoV display as demonstrated in Great Scott's latest video - HACKED!: Old Fan becomes a POV Display
As always, all notes, schematics and code are in the Little Arduino Projects repo on GitHub.
read more and comment..