Opencockpit and usb output

[jespergb]

I want to build some "lights" using the opencockpits usb output board. There's only one GND on the board so how do i connect more LED's? Do i need some kind of split cable or how to do it?

Also what is the best way to connect to an LED - just solder the cable to the led-legs? or?

Sorry i'm kinda new to this - hope i can get some help

[dc8flightdeck]

If you are using the onboard USB power to light your LEDs you connect each LED ground to each individual output connector on the board, and the LED + side all connect together to the power + terminal on the board. Ignore the GND. The positive side of ALL the LEDs maust be ganged together to the + slot on the board.

If you use an external power supply then you connect the power supply - to the GND slot on the board and then connect the power supply + directly to your LED or light bulbs. Once again the + from ALL of the LEDs are ganged together.

So to sum it up, The 64 outputs at this card share a common +5V. This is different from the 38 outputs at a Master card that share a common GND.

In SIOC you do not have to take these differences into account, writing a '1' to an output in SIOC will always make the led light.



justin

[pdpo]

Hi there,

also dont forget to protect the leds and the card with a resistor for each led (limit the current through the led)

one remarks about the above posst. The USBoutput card allows also tu use higher voltage for the outputs. Hust need to take care that the jumpers are in the right position so the higher voltage doesnt reach the usb port electronics. These are then powered by the USB port of the PC and the outputs receive there voltage from the external power. I think the card allows up to 50V external power. Of course if you only power leds then 5v is enough.

Greetz Peter

[jespergb]

Hey,

Thanks for the answers - i'm still abit confused (not very good in electronics)

so lets say i have 2 LEDs i want to connect to that board. Where should the two wires from each leg of the LED go? Should they go to the numbers on the board? or - can you try to be more specific?

thanks!

[dc8flightdeck]

(1) What voltage are your LEDs set up for? As Peter pointed out, LEDs are basically 3v DC. If you are using the card's onboard power it provides 5v. You will need a resistor on the positive side of each individual LED to make them work on 5v. Im not sure what size resistor you need for this. You should be able to purchase LEDs with resistors already connected. I purchase LEDs configured for 12v on Ebay.

(2) LEDs are ground and positive specific. The ground side of each LED connects to the numbers(outputs) side of the card. So one LED ground goes to 0, One LED ground goes to 1, etc. To quote the manual, "Numbered from 0 to 63, there we can connect the ground poles (GND) of leds, lamps or another elements." The posotive side to all of the LEDs you must connect together into one connected bundle and then connect this bundle to the Positive (V+) on the card.

(3) WARNING: If you want to connect an EXTERNAL power source for the outputs with a different voltage than +5V and you have the jumper1 and jumper2 connected, the card will be damaged.

Take a close look at page 3 of the manual. It shows 5 volt light bulbs (the circles with x through them) connected to the card and it also shows LEDs with resistors between the LEDs and the 5v power supply.

http://www.opencockpits.com/uploads/...utputs_eng.pdf

[kiek]

As Peter pointed out, LEDs are basically 3v DC. If you are using the card's onboard power it provides 5v. You will need a resistor on the positive side of each individual LED to make them work on 5v.
]

Just for clarification: leds have a 'Forward Voltage' ranging from 1.5 to say 4.6 V. Most of them are 1.5 V. A led with a forward voltage of N Volt will work with any Voltage greater then N Volt. However, a led has no resistance, so that's where the resistor comes in. You have to put a resistor in series in order to limit the forward diode current (through the led) according to its specification (mostly 20 mill ampere), otherwise your led will burn to death immediately...

At this page you can calculate the resistor depending on Supplied Voltage, Forward Voltage and optimal diode current: led calculator

[jespergb]

Ok, I think i get it now. Some more questions:

1. How do i know which resister to buy?

2. Should i buy a resister for each LED or just one for all of them set to the 5v on the board?

3. The LED's available at OC - are they 3v?

4. Is there a good way to collect all the wires into one (to be inserted to the 5v)? Is there some kind of device that will collect wires - or how should this be done?

Thanks in advance

[kiek]

1) by calculation, see the led calculator link in my post
2) each led needs a resistor
3) that depends on the type of led, ask for specifications. But every electronics shop sells leds, there's no need to buy them from OC.
4) the only thing that's important is that he current can flow, so make good contact. How you physically solve that is up to your imagination, but it is certainly wise to use a bread board or something like that to solder the +5V wires together and let one wire go to the +5V.

[dc8flightdeck]

These LEDs already have resistors attached,
http://cgi.ebay.com/Wired-LED-Bright...item27acaccd3e

Search Ebay and there are other colors available.

Regards,
Justin

[dc8flightdeck]

Thank you for the correction, Im used to dealing with specific RGB LEDs that are about 3v.