Hi
I need some help ,I have got hold of some 5 volt leds with built in resistors ,just wondering if it would be possible to use with pokeys 57 e and the ext card if i cut the resistor on the ext card .and just connect the led on the original feed from the ULN2803A chip on the board without resistor. If so could I use all outputs like this if leds have built in resistors?
Definitely you can. You just need to calculate the voltage you need to supply to extension card. I feed 12v to my extension cards ( built them myself) where I use LEDs from Christmas lights. Also have one ext card designed for 5v feed (used for 6-pack and AFDS LEDs).
see http://elephantair737.blogspot.ca/p/mip.html (http://elephantair737.blogspot.ca/p/mip.html)
:2cw:
Nick
Thanks for that Nick ,so what do you mean, I have to calculate voltage can I just supply the ext card with 5 volts as my leds are 5 volts ?
Mick
No, you will need to use higher voltage and calculate your needed resistors value (including built-in resistor). I would suggest you use 12v and calculate from there.
Do you know what forward current your LEDs are for? Take one of your LEDs and experiment with it. You could use http://led.linear1.org/1led.wiz (http://led.linear1.org/1led.wiz)
There is a Pokey extension card for LEDs already built by a company in Europe. So easy to use, and very cheap. Why create something from scratch?
The led extension board can be used with higher voltages up to 25 volt. The normal voltage for the onboard resistors is 5 Volt. Or you can ask me to leave the resistors out, I will bridge the gap where the resistors were.
If you want one like that just ask me.
Regards, Wendy
flightsimparts.eu
Thanks for that wendy ,sounds good to leave resistors outfor me ,I shall let you know in the next few days
Kind Regards Mick