Matrix Orbital Corp

Hi,

I have a VK204-25, but the wide voltage model, which connects to the 12V. Therefore, I'm wondering if the + side of the GPOs are connected directly to this 12V, or are they somehow 5V?

I plan on hooking up 6 LEDs to the GPOs. They are blue and red.

http://www.adpmods.com/xcart/customer/p ... 105&page=1
http://www.adpmods.com/xcart/customer/p ... 105&page=1

Can I connect these directly to the GPOs? Should I be adding in my own resistors (if so, what OHM resistors for the LEDs I posted) and not using the built in ones? Or are the built in ones for a different purpose, and I should add mine in, and run through the built in ones also.

Can I connect more then one LED to each GPO?

Thanks for any help

After doing some research this is what I believe I have to do.

I'll just run 1 LED to each of the 6 GPOs to keep things simple.

First off the blue LEDs are 3.4V and 25mA current. These numbers are between typ and max so they should give a bright light.

The reds are 2.3V and 20mA.

I'm going to use my own resistors so, I'll bybass the existing ones by running a wire across each.

Now, for the resistors I should use.

I'm assuming the GPOs are 5V, but I still need to know, since I have the wide voltage model connected to the 12V, if this still remains true, or if the GPOs are 12V.

Anyway, assuming they are 5V.

For the blue LEDs. 5V-3.4V=1.6V
1.6/0.025=64OHM resistor

For the red LEDs. 5V-2.3V=2.7V
2.7/0.020=135OHM resistor

Since the closest resistors I can buy are 75OHM and 140OHM the LEDs in final will be getting 21.3mA (blue) and 19.2mA red.

Does this seem correct? So in final I can set this up by getting 3 reds, 3 blues, 3 75OHM and 3 140OHM resistors. Then for each LED, connect the + to the GPO, negative, through my new resistor, and to the negative on the GPO. Then run a jumper wire from each negative on the GPO to the corresponding feedthrough hole on the built in resistors?

Is there anyway I can avoid soldering on the jumper wire?

Thanks again, hopefully I answered some of my own questions. Let me know if I'm on the right track.

Hello...

To be perfectly honest, you answered most of your own questions!! Even though this unit is a 12 Volt module, a voltage regulator is used and the GPO's use the regulated 5 Volt rail. For a complete background on how to calculate these values, please see the following link: http://www.lcdforums.com/forums/viewtopic.php?t=1527

Unfortunately there is no "EASY" way to do this with through hole resistors and a breadboard may be required. Your setup will be identical to how it's represented on our PCB.