Serilux 1

In the beginning there only was the Parilux device. It was a descendant of the Parino card: a 12 relay card with 5 inputs and two open collector outputs. But the days of the Parino were counted, so I designed the Parilux.
Still, even the Parilux was rather complex for novice programmers. Too many options. Too many parameters. Too little feedback. As a beginning programmer, you need positive feedback in the first place. No need for high tech stuff, just plain 1 on 1 feedback action ratios. So the Serilux was designed. It is a simple device, with a simple challenge and simple source code.

The circuit

On the right you see the circuit drawing for the Serilux device. The name Serilux is based on the Parilux device:

abbrev is for
Seri This gadget runs off the Serial port. Hence the letters 'Seri'
lux The gadget reacts with light: hence the name lux (Latin for light)

The circuit is simple. It can best be made without a PCB. Just connect a resistor and a bicolour LED to pins 3 (TxD) and 4 (DTR) of a female DB-9 connector. Dril a 3 mm hole in the DB9 case and that's it!

The pins can have two states each, resulting in four conditions for the LED:

Case TxD state TxD voltage DTR state DTR voltage LED voltage LED
0 0 +12 0 +12 0  
1 0 +12 1 -12 +24  
2 1 -12 0 +12 -24  
3 1 -12 1 -12 0  

The serial port voltages may vary between systems. Laptops typically have lower levels than desktop systems (which have higher power powersupplies). The absolute values range between 5 and 15 Volts. The resistor has been scaled on the basis of 15 Volts. At 30 Volts over the LED, the resistor brings down the current to something like 6 mA.

What it looks like

On the right you see a built Serilux device. It is not much more than a DB9 connector in a metalized plastic hood that has a small hole in it to accomodate a 3 mm LED. Anyone with a small drill and a solder iron can make this device. So everyone who really wants to master the art of programming can get started! And for almost free.

Estimated costs for the Serilux 1 (see below): € 0.50.
So for half a euro you can get cracking at code generation! Or you can buy ready built devices for a few bucks more.

In the picture you can see the LED just above the plane section of the DB9 hood. What's inside you can see below and in the last section of the online album dedicated to the Parilux device: http://www.mijnalbum.nl/Album=HYMOUBUW.


Here you see an airwire picture of the built circuit. The camera had difficulties focussing due to the high amounts of white between the wires. But you see how Serilux 1 is made: just insert some wires in the soldercups of the DB9 and you're done! What I did was:

  1. Insert cathode of LED into cup 3
  2. Solder it tight
  3. Bend the LED so the head fits the hole in the hood
  4. Cut the LED anode just before the bend
  5. Cut the resistor to size and solder one end in cup 4
  6. Solder the other end of the resistor to the LED anode
  7. Check for shorts! These are all bare wires.
The prices I mentioned in this section are retail prices in Germany (http://www.reichelt.de).

Buy one NOW!

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Bill of materials

Here is the BOM (Bill Of Materials) for the Serilux 1 device. The table speaks for itself.

Part Description Amount Price Total
DB9 DB9 female connector 1 0.10 0.10
DB9 hood DB9 connector hood 1 0.20 0.20
LED Two colour LED, Kingbright L-937EGW 1 0.12 0.12
Resistor Current limit resistor, metalfilm, 1/4 Watt, 1000 Ohms 1 0.08 0.08
Total for hardware 0.50
Profit Engineering charges 1 4.00 4.00
Grand total 4.50


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