lm3919?

This is the place for any magazine-related discussions that don't fit in any of the column discussion boards below.
goner19
Posts: 84
Joined: Wed May 20, 2009 8:15 pm
Contact:

Re: lm3919?

Post by goner19 » Thu Feb 18, 2010 8:50 pm

heres a pic
hope you can see it
i know its a little messy but i got big fingers lol...

on the side is the voltage divider i made t

the brown wires coming off of 6 and 7 dont go anywhere right now
they were there for a pot test i tried...

Image

goner19
Posts: 84
Joined: Wed May 20, 2009 8:15 pm
Contact:

Re: lm3919?

Post by goner19 » Thu Feb 18, 2010 8:54 pm

can anyone see that image?

i cant


second attempt

Image


psycho
Posts: 388
Joined: Thu Jan 10, 2008 8:13 pm
Location: Northwest Indiana
Contact:

Re: lm3919?

Post by psycho » Thu Feb 18, 2010 9:01 pm

I believe pins 6&7 need to be connected - IIRC, they are feedback voltages or something for the chip. I can't look right now because I am busy as a beaver...

goner19
Posts: 84
Joined: Wed May 20, 2009 8:15 pm
Contact:

Re: lm3919?

Post by goner19 » Thu Feb 18, 2010 9:04 pm

no worries kevin...some times beaver keeps me busy too...lol....
(thats a joke)
=)

pin 6 goes to 7 and 7 goes through a 1k to the ground...

sghioto
Posts: 322
Joined: Wed Dec 26, 2007 5:16 pm
Location: Colorado
Contact:

Re: lm3919?

Post by sghioto » Fri Feb 19, 2010 8:34 am

goner19,
pin 6 goes to 7 and 7 goes through a 1k to the ground...
What are you doing! I posted the schematic for you.
Correct, pin 6 goes to pin 7 but the 1K resistor connects from pin 7 to pin 8.
The 4.7K connects from pin 8 to ground.
I tried to view your photo on flicker but it's marked Private.

Steve G.

goner19
Posts: 84
Joined: Wed May 20, 2009 8:15 pm
Contact:

Re: lm3919?

Post by goner19 » Fri Feb 19, 2010 5:25 pm

wow steve i guess youre right

but some how it works now!!!!!

putting the pot on pin5 between the + and -
seemed to do the trick

right now i do have pin 8 going straight to ground w no resistor
but it seems to be working
ill try it the way it is in your test diagram,,,
is 6,7,8 some type of voltage divider?
would it effect the sensitivity at pin 5?

hey i really want to say thanks to everyone who has helped me here
ill make sure the pics are open so you can see them
there are some pics from burningman and they are nsfw...=)

tonight im gona try and add the second lm3914 and see if i can get it to work

sghioto
Posts: 322
Joined: Wed Dec 26, 2007 5:16 pm
Location: Colorado
Contact:

Re: lm3919?

Post by sghioto » Fri Feb 19, 2010 5:53 pm

goner19,

Your're right it will work that way. With pin 8 tied to ground you are using the internal reference voltage of 1.2 volts. This means a 1.2 volt input on pin 5 will turn on all the LEDs in the bar mode. The resistor divider R1 and R2 allow you to change the reference value up to 12 volts if required. The supply voltage needs to be at least 2 volts higher then the reference voltage. Using a 5 volt supply the maximum reference you can set is about 3.9 volts.

Steve G.

goner19
Posts: 84
Joined: Wed May 20, 2009 8:15 pm
Contact:

Re: lm3919?

Post by goner19 » Fri Feb 19, 2010 7:20 pm

wow steve youre good
you can just figure that out by looking at it?
ultimately i will put 6 and 7 on a pot like buckeyes diagram

he too has 8 going straight to ground

i just want to make sure is sensitive enough to run off of an 02 sensor
plus id like to use his data for the fuel ratio calculations...


i did the double up and it works too!!!! too cool
now i have to find someone to make me a pcb for it

goner19
Posts: 84
Joined: Wed May 20, 2009 8:15 pm
Contact:

Re: lm3919?

Post by goner19 » Sun Feb 28, 2010 1:20 pm

right on thanks again for all your help guys

i really have the hang of the lm3913

ok here is my last question.
im about to weld in the bung for the 02 sensor
sense the output single from the sensor is so small
would tapping it for the lm3913 affect the pulse to the electronic control unit?

do i need to weld in a second 02 sensor and run them seprate?

thanks in advance

goner19
Posts: 84
Joined: Wed May 20, 2009 8:15 pm
Contact:

Re: lm3919?

Post by goner19 » Fri Jun 11, 2010 10:28 pm

hey psycho....you out there?
i got a business prop for you
[email protected]

anyways finally got the 2nd o2 sensor in my bmw and the pcb built
i hope to put it all together this weekend

ill post pics when its done
thanks again guys for all the good advice...

Post Reply

Who is online

Users browsing this forum: No registered users and 41 guests