Conductive pens???

I had a thought today while spacing out in class after deciding to add illuminating my 4x4 switch to my summer cluster and radio color change project. Since conductive pens can be used to create prototype circut boards or alter existing ones why not use it to create the 4x4 LED board? There really isn't a need to go through the hassle of etching a board for such a simple circuit. This would knock the cost of the mod to $10 to ship the pen to my door and with a milk jug, a couple of LEDs and spare wire I am in business!

Thoughts? Is the end of semester stress getting to me (YES!) or am I on to something here?

 

why would you do this when someone has already made a board for us?

 

Just go to radio shack and pick a pen up, they work good.

 

$10, some spare parts, and 20 min of work or $40 and 10 min of work?

Plus I don't care if it looks pretty, no one is ever going to see it.

 

This sound right?


Materials:

Thin flat piece of plastic
tool to cut plastic
conductive pen
Glue (Hot, super, etc -something that will work with your materials)
Sharpie
Six Leds
470 ohm resistor
wire to get power from Climate Controls
Wire splices


Prep: remove and disassemble 4x4 switch, cut out flat piece of plastic

If using a plastic you can see through place on top of the back of the switch face. Trace the inside of the inside and outside switch walls all the way around to the halfway mark. (If plastic isn't see through use paper...)

Cut out the shape you traced with scissors, shears, knife, dremmel, etc

Find an image of one of the existing boards and figure out where the LEDs go. (very simple)

Here is Scooter's


This is where a thin, soft, bendable plastic like a milk jug would help- Poke 2 holes at each spot where the leds need to go for the leeds. Poke 2 more holes for a resistor and 2 larger holes to accomodate your + and - leads

Insert LEDs into slots. Good idea here is to insert them all so that the + end is up.

With the cunductive pen draw out the circut, be sure to surround each terminal to make a pad which will have a good connection. Wiring them in series would make this a lot easier.

Glue everything into place. (This is one part that may need tweaking)

Cut all leads off close to the board

Install into switch, wire into climate controls with splices, check for power, reassemble.

 

updated with images.

Props to Scooter for posting his idea and mod which lead me to this one. Here is his thread.

Also here is the link to where you can buy a pre-made board.

Back to studying...

 

Screw studying.

Another cool option in making your own jsut came to mind. Look at the finished product. The 3 sets of LEDs are for the 3 positions of the switch. At each the top LED is for the mode display (2HI, 4HI, 4LO) the bottom is for the arrow.

This means that by changing the color of the bottom LED the arrow could change color with mode.

With this in mind when I do mine I will be doing white LEDs for Mode, Blue for the arrow when in 2HI, and Red when the arrow is in 4HI or 4LO. That way I will remember to take it back out of 4x4 before getting back on the pavement.




Edit: While I am at it I am going to buy 2 blinking red LEDs one to put in the 4LO arrow slot, the other to mount somewhere in the cab with a relay that will give it power anytime the key isn't in AUX power as a dummy alarm light theft deterrent. On closer inspection anyone with a brain would realize that I don't even have power locks and thus no sec. system, but hey, can't hurt.

 

Hoping to get my front 5100s in today, maybe while I am sitting around waiting on the alignment and whatnot I will pop out the 4x4 switch and see if this works.

 

Yeah I read that and it didn't click the first time, no worries, just need a bigger resistor.

Front 5100s fell through yesterday, so I wasn't given the opportunity to try this yet. Maybe Friday. I hate finals!

 

Please check out post #7 on my DIY Cheap 4X4 Switch Illumination thread. It reads,

"I have the LEDs in series. They each have a 1.8V drop across them. I checked with a voltmeter. The resistor has 2.5V volts across it. That adds to 13.3 volts, which is the output of the power supply I was using to test the circuit on the bread board. The circuit draws 5 mA. I tested it with an ammeter. Ohm's law also confirms it.

V = I x R
2.5 = I x 470
2.5/470 = I
0.005 = I
​

I am not drawing 1.5A, but 5mA. The resistor doesn't even get warm. That works out to 12mW across the resistor."

I believe Rcbs204 miscalculated the current. There is only 5mA going through the circuit. There is no noticable heat from the circuit at all. I've been using it for nearly 5 months. No dash fire! I'm a registered (licenced) professional electrical engineer. I think I know what I'm doing.

 

By the way, if you do this, don't mount the LEDs above the circuit board the way I have shown in the picture. Mount them right up against the circuit board. I have changed mine. The LEDs mounted agains the circuit board will give a more even light distribution because the light source is further away from the front of the switch. This, of course, will give you light bleed, if you are considering using diffferent colours for the different positions of the arrow.

 

Or you could buy mine and save all the trouble!!

 

Man, I REALLY misread the title. I thought, how the hell would someone know that their pen-is conductive?

 

no, no tragic lightning strike story here.

 

So flight... whats the verdict?

 

That finals still suck. I'll head to RadioShack tomorrow though I hope. Its either this or replace my front shocks, we'll see which happens depending on how much I have to get done

 

sub'd

 

Well it works!

Too bad my resistor took a crap on me and blew out my LEDS before I could even install it. Instructions work pretty much perfectly, only thing I would add is to attach the wires to the board poke 2 holes close together, string the wire through both and twist back around on itself.

 

Was is to weak or did you use the same one scooter did? Also did you get the pen at RS, they told me they didnt have it.....

Looks good tho, I am excited to see it in action..