Bread Board Experiments

Yesterday I was experimenting around a little with the Darlington Driver 50V / 500mA Transistor array chip model number ULN2803A. I wired up a simple circuit on my Bread Board with 2 mini Songle 12V 10 Amp relays, some resistors, micro tactile buttons, wires, a single red LED and the project 2 LED flasher circuit that came with the starter kit I got.

Now this is really simple setup using the Darlington Transistor

array chip in that my micro buttons (in this case) are switching on a stepped down 9V current through the resistors to simulate a low current input to the Darlington array chip. This is ideal since I intend on using an Arduino to control input signals to the chip, and Aduino uses a low 5V output, same as a USB device. On the other side (Outputs) of the Darlington array chip I have the necessary voltage needed to trigger the magnetic coils of the mini Songle 12V Relays and as you no doubt already know that on the switch side of the relay I can have anything I want to activate up to 10 Amps, which is a lot of current. I can use higher rated Relays if I need to power anything that requires more than 10 Amps.

So in the experiment yesterday I have it so when you press once of the micro buttons the single red LED turns on through the switch of one relay and when you press the other button the small 2 LED flasher circuit turns on through the switch of the other relay. Now keeping in mind that for a low power input of 5V (USB) I would not need the resistors in front of the input pins on the Darlington array chip, this makes for a very small space saving potential PCB board to control stuff from my dash software I have been developing in Unity 3D. I'm planing on using the Arduino because so far it's what I have found that communicates well with Unity 3D both as a means of controlling from the Arduino and sending information too the Arduino.

2 Low Input to 2 Higher Output Relay Board

I did up a quick diagram of the little PCB board I made with some great help from Andrea lannaccone from Face Book. There are smaller ways to do this but this is pretty small too, you can do this type of switching with a Transistor too. For what I am doing with my Top Countdown Indicator lights to activate the switch lights on my Lower Console I only need one side of the board but there was room on the board to have the same ability twice so at least I have an extra setup for should I need to do something similar again. :) 

PCB Board Installed

I installed the small PCB board later today just overtop of the other Relays board I had made a few weeks ago. I have the power wire (blue) going from the fuse panel I installed under the passenger side Hush panel into the magnetic coil and switch terminal of one of the mini Songo 12V 10 Amp Relays, this will supply power to energize the coil and provide power to one side of the Relay switch. The other blue wire you can see coming out of the top of the Relay is the 2nd power wire on the other Relay switch terminal, this wire goes into my Lower Console to supply power to the switch lights. The Relays switch will connect the two completing the circuit. The two input wires Red and Black that connect to the Optocoupler I have going into a couple of spare sockets I had available on my Molex connector for my LCD and GPS screens. Those will provide the low input signal to activate the Optocoupler once the Countdown indicator reaches it's last light, this will in turn activate the Relay making the connection as described before. Tomorrow will be the big day I test this out so if all goes well I'll be doing a video to demonstrate the final effect.