Stack lights and horn controller
From CaveLab
This page is kept for historical interest. It may document projects or methods that are obsolete and/or no longer relevant. The information here is not kept up-to-date.
This module was part of the rack box project — which was terminated when I moved out of my first apartment.
This module was part of the rack box project — which was terminated when I moved out of my first apartment.

LTCU installed in the Rack box
A control module for a green, yellow and red stack light, and signalling horn.
Details
This is the Rack box alarm handling unit. It controls the stack light, strobes and horn. Six different signals can be displayed, according to alarm situation. If mute is active no signals is given. The power transistors for the stack light used to be located inside the module, hence the heat-sink. They have been moved to a separate power transistor unit.
Video
Signals
Nr | Situation | Green | Yellow | Red | Strobe | Horn | Horn w/muted |
---|---|---|---|---|---|---|---|
1 | Flashing | 0.1 s | |||||
2 | Rack temp | Steady | Flashing | Yellow | 1 s | ||
3 | SIOS alarm | Flashing | Yellow | 1 s | |||
4 | Serial offline | Flashing | Steady | Yellow | 1 s | 0.1 s | |
5 | Module offline | Steady | Flashing | Red | 1 s | 0.1 s | |
6 | Supply error | Flashing | Red | 1 s | 0.1 s |
I/O
Inputs
- Signal 1
- Signal 2
- Signal 3
- Signal 4
- Signal 5
- Signal 6
- Mute
Outputs
- Stack light green
- Stack light yellow
- Stack light red
- Strobe yellow
- Strobe red
- Horn
- Lifesignal (to Module stability monitoring unit 2)
- Lifelight
D-Sub 25-pin
- +5V
- 0V
- Strobe yellow
- Strobe red
- Horn
- Lifesignal
- Signal 1
- Signal 2
- Signal 3
- Signal 4
- Signal 5
- Signal 6
- Mute signal
- Stack light green
- Stack light yellow
- Stack light red
Source code

https://github.com/thomasjsn/AVR-Stack-lights-controller
Gallery
Testing with Simulation 6 I/O
LTCU installed in the Rack box
Schematic drawing
Parts used
Qty. | Part |
---|---|
1 × | AVR ATtiny2313-20PU, DIL-20, 20 MHz, 18 I/Os |
1 × | Capacitor, aluminium electrolytic, 10 µF, 25V |
2 × | Capacitor, ceramic, 22 pF, 100V |
1 × | Capacitor, ceramic, 1 nF, 100V |
1 × | D-sub soldering cups, 25 pin male |
1 × | DIL socket, 20-pin, 7.62mm |
1 × | Enclosure, plastic (1591 FL), 120x65x40mm, flange |
1 × | Fuse 5x20 mm, 400 mA, fast-acting |
1 × | Fuse holder, open, PCB, 5x20mm |
1 × | Fuse holder, open, PCB, Protective cover |
1 × | Heatsink, 6K/W @ 10W, 37.5mm 49g |
1 × | LED 5mm coloured clear, Green, 2.1V, 20mA, 30mcd, 10° |
1 × | LED 5mm, Green, 2.0V, 10mA |
1 × | LED 5mm, Orange, 2.0V, 20mA |
1 × | LED 5mm, Red, 2.0V, 20mA |
1 × | LED holder 5mm, RTC51, black plastic |
96 cm2 | PCB, stripboard, 100x160mm, 160cm2 |
1 × | Quartz crystal oscillator, 4 MHz |
11 × | Resistor, carbon film, 0.25W, 330 Ω, 5% |
8 × | Resistor, carbon film, 0.25W, 4.7 kΩ, 5% |
7 × | Resistor, carbon film, 0.25W, 10 kΩ, 5% |
7 × | Transistor, NPN, 100 mA, 45V, 0.5W, BC547B |