LEAP#346 S/R Latch with NAND Gates
Yet another implementation of a Set-Reset flip-flip, this time using NAND gates.
The NAND gate implementatation has an undefined state with both inputs high, whereas a NOR gate implementatation has an undefined state with both inputs low.
Consequently NOR gates are typically used for active-high SR latches and NAND gates for active-low SR latches. A good example of this is the application in touch sensors, where active low makes sense. See the Boldport Club tap and mostap projects for examples of this.
As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub
Here’s a quick demo:
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LEAP#345 Boldport Club MOSTAP
The MOS TAP circuit was originally published in Elektor magazine in Feb 1975. It was an update or the original TTL Tap circuit to use “state-of-the-art” COSMOS (CMOS) components.
In practical terms, that means 4000-series logic instead of 7400-series logic.
The Boldport Club version of this venerable circuit makes an additional improvement by replacing the output stage BJT drivers with 2N7000 n-channel MOSFETs so that the project really does live up to it’s name!
I’ve added a few mods of my own - a mode switch and a test jig mounted on the beautiful Boldport box (too good to throw away).
As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub
Here’s a quick demo:
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LEAP#344 MicroPython on the ESP8266
I first heard about MicroPython from the kickstarter campaign to open source the software.
Although it makes more sense to use it with a more capable board, I’m starting with a test on a 512kb ESP-01 module.
Nice … python on a micro, running Star Wars ascimation!
As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub
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LEAP#343 ESP8266 DHT11 Sensor Reading
The DHT11 sensor is a very cheap and common sensor that provides readings of relative humidity (20-80% ±5%) and temperature (0-50°C ±2°C).
I’ve used this before with an Arduino, this time I’m testing with the most basic ESP8266 board - an ESP-01, which exposes one free GPIO. For coding I’m using ESP8266 core with the Arduino IDE, and the Adafruit sensor library to interface with the DHT11.
As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub
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