This project is an alternative hard disk activity indicator build using 10 LEDs. It works by rotating the LED light like a dekatron tube. The article explores many ways to connect the hard disk activity indicator to motherboard and concluded to negative edge triggered with a lowpass filter. On the link below you can find construction details and schematics. [via]
Spindicator: hard-disk activity indicator – [Link]
LED’s are great display tools. Their prices have decreased to a point where they are replacing more conventional light sources. In one sense their characteristic need for low voltages is an advantage e.g compatibility with I.C drives, but this voltage requirement can also be a disadvantage. I wanted to light some LED’s in a simple sign application, nothing fancy, but I needed to decrease the utility line voltage to a LED-compatible value for this application.
A power source for simple LED projects – [Link]
Here is a white-LED-based emergency light that offers the following advantages:
1. It is highly bright due to the use of white LEDs.
2. The light turns on automatically when mains supply fails, and turns off when mains power resumes.
3. It has its own battery charger. When the battery is fully charged, charging stops automatically.
Low cost / Automatic Emergency Light – [Link]
This project uses an LM3915 bar-graph IC driving two sets of ten LEDs for a 30dB range. The circuit is unique because it has an additional range of 20dB provided by an automatic gain control to allow it to be very sensitive to low sound levels but it increases its range 20dB for loud sounds.
Sound Level Indicator – [Link]
This is a spectacular but completely useless project. It lights Ultra-Bright LEDs in a sequence and each LED flashes brightly very briefly. The LEDs light-up going around and around since they are mounted in a circle (on a CD), then they pause before chasing again. The very brief flash of each LED (15ms) and the pauses (1 second) reduce the average current so the battery should last a long time.
6V Ultra-Bright LED Chaser – [Link]
As a keen cyclist I am always looking for ways to be seen at night. I wanted something that was a novelty and would catch the motorists eye. So looking around at my fellow cyclists rear lights, I came up with the idea of ‘NITE-RIDER’. NINE extra bright LED’s running from left to right and right to left continuously. It could be constructed with red LEDs for use on the rear of the bike or white LED’s for an extra eye catcher on the front of the bike.
Nite Rider Lights – [Link]
The system is contructed of 16 custom built PCBs, each containing a PIC16F1827 microcontroller which receives data via I2C from a master board and controls 3 MAX6964 LED Drivers via I2C – one each for red, green and blue components. Each board then runs two ribbon cables of 8 RGB LEDs. The master board is running on a PIC18F26J50, a very powerful little PIC with an awful lot of I/O capability. Its reading the animations from an SD Card formatted with FAT32 using an SPI interface, it then chunks this data up, and sends it via the main I2C bus to the slave boards. [via]
Illuminatrix LED Project – [Link]
This video shows a LED powered by a 0.1 Farad capacitor. First the capacitor is charged at 5V and then it is discharged through the led. The led is light for a few minutes after power is disconnected.
Led powered using Super Capacitor – [Link]
This project shows how to build a 24×6 LED matrix driven by an Arduino board. It uses 3 shift registers to control the columns and a 4017 decade counter IC with 6 transistor for scanning the rows. Check schematic and project details on the link below.
DIY 24X6 LED matrix – [Link]
This project shows how to build a LED matchstick that is light up if strike it against a normal matchbox filled with neodymium magnets.
The LED matchstick has an inductive sensor that detects the magnetic field as you strike the matchstick against the matchbox and it lights up a LED in a flickering fashion. The power to the matchstick is through a 3F/2.7V supercapacitor and a DC-DC converter. As the LED lights up, the supercapacitor discharges and eventually the matchstick splutters off just like a normal matchstick.
Fire-free LED Matchstick – [Link]