tech question 7seg Display

[jackpilot]

Too hot outside , spent the afternoon building a dummy IRS display (until it gets functional)
I used MAN384OA . the tech sheet says 2.2V /max 3V /absolute max 6V.
They are all wired in parallel using 3V on the pic
I have to use 5v.
Any advice?

[Maurice]

The ATX power supply has a 3.3 V output. Not sure the amperage rating but that should do for sure.

Maurice

[saabpilot]

I suggest a small power supply that can give +3V if no ATX power supply available.
Or put a resistor on the +5V line.
5V constantly on will otherwise I believe burn the LED:s and might be too bright as well.

Bjorn

[jackpilot]

Not sure about those leds., mean how to compute a resistor value as all segs are lit.
I tries one 220 Ohm for the whole row: no light
100 same
40 nice dim but the resistor could boil an egg!
I cant put a resistor for each as they are in parallel.
My knowledge of electronics is ltd.
I always can hook it to the PSU 3V but I'm trying to keep everything 5V.

Morality: how to create problems when you do not have any from start.

[jonesthesoftware]

LED's are not normally kept powered on continuously but "strobed" by their driver circuit. As long as it's faster than 25-30 times per second it looks as if they are on continuously this means of course that the resistor feeding each LED will not get so hot due to the "duty cycle" How are you driving the LED's?
regards
geoff

[jackpilot]

Just an eyecandy thing for the moment as the IRS is not emulated via software (yet)

So I put all common together and all seg together to get 88888 fed by one plus and one minus of 2X1.5v batteries in series.
Probably not very professional!

[727737Nut]

Not sure about those leds., mean how to compute a resistor value as all segs are lit.
I tries one 220 Ohm for the whole row: no light
100 same
40 nice dim but the resistor could boil an egg!
I cant put a resistor for each as they are in parallel.
My knowledge of electronics is ltd.
I always can hook it to the PSU 3V but I'm trying to keep everything 5V.

Morality: how to create problems when you do not have any from start.

Jack,
Just use a 40 Ohm 10watt resistor and see what happens.  May have to go a little bigger but doubt it.  They will take allot of heat.   Don't ask how i know!  LOL

[jackpilot]

Thanks Rob will try that

I hope It will be interfacable one day.
Actually the keypad is from a real one!