Programmable outputs

awattam · Post by **awattam** » Thu Aug 25, 2005 11:38 am

Got my car (Capri 2.0) running on megajolt. The difference is amazing, so much stronger pulling through the revs and starts much better from hot. Not had chance to look at fuel consumption yet but I recon that must be better as well.

Anyway.......My question is about the programable outputs. I want to use them to run a shift light. From reading bits on here I realise i need to use an in line resistor with a LEDs to bring the current down. Also i got the impresion that the megajolt unit switches the earth rather than a 12v live as i expected. Can anyone confirm this?

I really want to sort this out so i can put the dash back together once and for all!

Oliver Sedlacek · Post by **Oliver Sedlacek** » Thu Aug 25, 2005 11:59 am

Yes, the megajolt switches the earth line. For a typical red LED with a forward voltage of 2V, the resistor needs to drop the rest of the 12V, i.e. 10V. For a beefy LED, 20mA is reasonable, so you want a resistor of around 500 ohms. If you aren't sure of the LED ratings, try something a bit bigger. Most LEDs wont tolerate 12V of reverse bias and may be destroyed if connected backwards.

awattam · Post by **awattam** » Sat Aug 27, 2005 9:38 am

That clears things up. Would it be ok to use 12v LEDs, save messing around with resistors? Going to try and sort this out over the weekend if I can.

greypride · Post by **greypride** » Sat Aug 27, 2005 11:54 pm

i did it that way for a quick fix, but when i wired 5 in series they were very bright!!!

now im using a cluster led from maplins and a 220ohm resistor

ckenyon · Post by **ckenyon** » Fri Feb 17, 2006 4:34 am

I was going to use the PGM 1 - 4 and the shift light to light up a series of LED's indicating what rpm the MJLJ thought it had. ie PGm 1 at 1000, pgm two at 2000 ect so that at 5000 rpm all five LED's would be on. So, I get 5 12V LED's and connect them up to +12v feed and the MJLJ connections are to switch to earth??
CK

MartinM · Post by **MartinM** » Fri Feb 17, 2006 11:30 am

Yep, that's perfect.

You are correct that MJLJ switches to earth.

Slightly confusingly (to me, anyway) is that you have to set the 'mode' of the outputs to 'high'. Get it wrong and you'll just have a reverse set of lights - they will go out as the revs rise!

You need a resistor (say 470 ohms) for EACH of the LEDs

Autosport Labs

Programmable outputs

Programmable outputs

Yes, the megajolt switches

Thanks Oliver

i did it that way for a

LED's anon

Yep, that's perfect.