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.

Lower Console Switch Lights As Part Of Dash Start Up Sequence

OK, here is a solution to something that has been kind of on my mind for a little while now....

So the Lower Console's button and switch lights are on all the time currently even if the ignition is off.... not good I know, bad, bad, bad... as these are not LED lights in this buttons and switches and given enough time would drain the battery for sure. So last night I had a thought pop into my head as I learn more and more about what many of the electronics components are capable of... my idea was this:

"Why not run a small 22 AWG wire from the last top countdown indicator on the top of the dash and run that to the base of a Transistor to activate a Relay that would turn on my Lower Console Switch and buttons lights?

That way when the dash did it's startup sequence, upon the lighting of the very last indicator a signal could be sent to activate my Lower Console lights."

Very simple I thought, so I got into a great conversation with Andrea lannaccone on Face Book this morning and we hashed out this wiring scheme. NOT using a Transistor as I had originally imagined but instead using an Optocoupler. Hey whatever works and is simple I always say ;)

You can see in the middle section of our diagram how we have introduced the wiring of the last countdown indicator LED to the Optocoupler which in turn triggers the SPST Relay which sends power to the Lower Console's switch lights making it an interactive part of the Dash start up sequence.... should be pretty cool when wired up and tested out ;)