Arduino Countdown Timer

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Ardumotive.com shows us how to build a 2-digit countdown timer using Arduino.

In this Instructables guide I will show you how to make your own Arduino two digit countdown timer. I made my own circuit by using the ATmega328 micro controller but this is an optional step. In this guide I will help you to make it easily on breadboard by using the Arduino uno board!

Arduino Countdown Timer – [Link]

Building a PIN Diode Geiger Counter

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“Kai” is in the process of building a Geiger counter based on BPW34 photodiode and explains his first step for the sensor circuit.

The common approach to protect the photodiodes from light is to use one layer of tin foil and connect it to ground. This should also protect the circuit against electromagnetic radiation. I’ve started with something different and dipped the diodes three times into liquid rubber (Plasti Dip). My hope was to at least allow some beta particles to reach the semiconductor material.

Building a PIN Diode Geiger Counter – [Link]

RELATED POSTS

Researchers develop LED covering full visible light spectrum

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Researchers have developed the first standard LED covering the full visible light, in collaboration with Nichia Corporation.

LED and OLED lighting, which is generally called solid-state lighting (SSL), is becoming more common as the next generation lighting. Evaluations of total luminous flux (a performance index for lighting) and color are important for SSL, and to evaluate those values, it is indispensable to measure the light intensity of each wavelength accurately based on spectral measurement. For accurate spectral measurement, the light source under test shall be compared to a standard light source as the reference standard. However, there has not been any standard light source covering the full that suitable for high accuracy spectral measurement of SSL.

Researchers develop LED covering full visible light spectrum – [Link]

RFID Computer login

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Luke wanted to login on his PC without having to type in a password. He solved this by using a RC522 RFID reader and an Arduino Leonardo.

There are various products on the market that would solve this problem from fingerprint readers to proximity dongles but i decided to see what i could knock up with parts i mainly already had.

Looking in my micro stuff i had a RC522 RFID tag reader 3.3v :

Also an 3.3v arduino Leonardo clone aswell based on a sparkfun pro micro which also can act as a USB device such as a keyboard. This is useful as if a 5v arduino was used a level shifter would be required due to the RC522 not being 5v torrent.

RFID Computer login – [Link]

Latching power switch uses momentary-action pushbutton

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Anthony Smith @ edn.com published a push button latching circuit able to control a load with a single push of a button.

The circuit in Figure 1 shows how you can use a simple, momentary-action, SPNO (single-pole, normally open) pushbutton switch to latch power to a load. Requiring just a handful of common, garden-variety components, the circuit works over a wide voltage range and is ideal for single-cell applications, because it can operate at voltages as low as 1V or less. Transistors Q2 and Q3 form an SCR-like structure that functions as a simple latch, Q4 switches power to the load, and S1 is the momentary pushbutton switch.

Latching power switch uses momentary-action pushbutton – [Link]

Single transistor provides short-circuit protection

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Keith Szolusha@ edn.com writes:

In certain dc/dc-converter applications, on-chip, cycle-by-cycle current limit may be insufficient protection to prevent a failure during a short circuit. A nonsynchronous boost converter provides a direct path from the input to the short circuit through the inductor and the catch diode. Regardless of current-limit protection in the IC, when a short circuit exists in the load, extremely high currents that flow through the load path can damage the catch diode, the inductor, and the IC. In a SEPIC (single-ended, primary-inductance-converter) circuit, the coupling capacitor breaks this path.

Single transistor provides short-circuit protection – [Link]

Wireless digital scale

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This is a wireless digital scale using ATTiny85 microcontroller and HM-10 Bluetooth low energy transmitter/receiver:

This scale is wireless. It may be useful where you can’t operate a normal scale, due to the weather outside, or if you don’t want to scare birds or other creatures away. With this scale you can weigh them. In this instructable, I used a 0 to 1 Kg load cell since I wanted to weigh hummingbirds and orioles that visited our nectar feeder.

Wireless digital scale – [Link]

4 Channel RC Servo Controller Board

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This PIC microcontroller based RC driver is able to control 4 RC Servo by on board independent 4 potentiometer , 4X3PIN header for RC servo interface, screw terminal for supply input, on board power LED, optional 4X3PIN header connector for external potentiometer.

Features

  • Microcontroller based design for greater flexibility and ease of control
  • Individual servo controlled via onboard preset or external potentiometer
  • Power supply input 5 VDC
  • Screw terminal connector for easy connection of the input power supply
  • Protection diode for reverse supply
  • Berg connector for connection of Servos
  • Power-On LED indicator
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 56.52mm x 64.14 mm
4 Channel RC Servo Controller Board – [Link]

ESP8266 Desktop Clock – WiFi Synchronised

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This project is a wifi synchronised desktop clock using 7-segment displays. The heart of the project is a ESP8266 board.

The ESP8266 is a awesome chip; with integrated WiFi, 80MHz clock speed, total 160kb RAM, 512kb of flash memory, and a ton of other features, it makes a regular Arduino look like a joke. The project shown in this Instructable is based solely on the ESP8266-01 module, unlike several other projects on the web where it is used in tandem with another microcontroller. This makes it great demonstration of the capabilities of the ESP chip.

ESP8266 Desktop Clock – WiFi Synchronised – [Link]