search143000

Hi I have just bought a knock link but I don't want to mount the box itself as it looks ugly I want to wire the current LEDs to a connector and then have a leed from this to an extra set of LEDs to be mounted in the cabin just ondering if it is this simple (can I cannect 2 leds to a cct that was ment for one ?) or do I need to take out the origomal leds or add resistors etc

any help apreciated

Thanks Alistair

Leviathan

Ive seen it done, the leds were mounted remotely from the box on another small piece of PCB with another lead from the box to the leds.
There was a pic of it on here a while ago.
Sorry i cant be anymore help than that though

Gary.

markwild

Alistair,

I'm attempting the same - see here

I've connected the Knocklink up, and this afternoon I've taken it apart and removed the original LEDS. I've wired up a network cable (using 6 of the wires) to the 5 +'ve leg holes where the LED were and a common ground. I now need to connect this to the plug I've fastened to the bottom of my LEDS, which are mounted in a circle in an A-Pillar pod. I'll post pictures when I'm done, hopefully this week !

Mark

Leviathan

Mark, how can you tell the +ive leg of the led?

Scott.T

iTrader: (2)

WARNING....

The Knocklink chip switches the grounds, so you need to wire all the LED's to the same 12V then connect the negative side of the LED's to the Knocklink chip (LM3914 I think).

Look at the PCB tracking and you will see.

I mounted mine on a thin piece of stripboard then mounted this (with trim tape) so that the LED's stick up inbetween the speedo surround black plastic and the clear facia (I did change all the LED's to 3mm tho').


[Edited by Scott.T - 9/28/2003 8:40:22 PM]

markwild

Scott, I've removed the LEDS and taken a common ground from the tracking on the PCB that was common to the LEDS. I've assumed that I can connect this to the common ground that I have connected the new LEDS with.

(Although I havn't connected it yet...)

Are you saying that the common rail is +12v and that the Chip switches the grounds ?

Mark

[Edited by markwild - 9/28/2003 9:31:14 PM]

Franko

If its COMMON ground it can not be switched that would interfere with the rest of the circuit... The positive leg is usually switched... Thus the positive leg would be in contact with the outputs from the IC (LM3914)

The flat side of the led is negative and the round side of the led is positive or the shorter leg is negative n the longer leg is positive...

Hope this helps...

Or is it the other way round??? (only kidding )

This is a good idea i'll be doing the same to mine when i get round to fitting it

[Edited by Franko - 9/30/2003 10:08:24 AM]

[Edited by Franko - 9/30/2003 10:10:23 AM]

markwild

OK - I'm being loose with terminology here - One leg of each LED on the knocklink is connected to a common track. The other leg of each LED is individually controlled.

However, I have removed the LED from the PCB (so can't see which leg was connected where) and connected a single wire to the common track.

I've then taken 5 more wires, one to each 'other' hole, where the 'other' LED legs fitted.

However, I've already wired the -ve legs of the replacement LEDS together and run 5 cables to the +ve legs. This is now in place in the car. I know that the common cable on the A-pillar is -ve, as I've tested the LEDS with a 9v battery.

If the common track on the knocklink is +ve, with each other wire being -ve, I need to invert them somehow (! ?)

Can anyone confirm this, or should I confirm it when I've completed the wiring and connections >

Mark

Scott.T

iTrader: (2)

Common LED connection is +
Negative side of LED goes to Knocklink LM3914

see http://hallbeng.jlab.org/datasheets/LM3914.pdf

markwild

BUGGER ! **** !!

I'll have to take the A-pillar apart and re-wire the LEDs in it then...

Thanks anyhow Scott. I'll post pics once I've got it working, but it'll probably be a weekend job now...

Mark

search143000

ok Guys cheers for that now we know which side is which I am sure I would probably have made the same mistake

but does anybody know if the origonal LEDs can be left in place as will as adding the extas on a lead as I would like it to work with or with out the extra lead connected as a just incase

thanks Alistair

RICH WILD

Has anyone thought of adding a buzzer to their knocklink?

I find at 140+mph you don't really want to be staring at the KL watching for knock.

A buzzer to accompany the red light would be much better.

Cheers

Rich

Franko

Looking at the data sheet from Scot.T in the above post it seems the LM3914 is capable of driving n extra L.E.D connected in parallel with the original LED... but it also says the output current is programable so depending on how the rest of the circuit is designed you may or may not be able to run two LEDS from one output...
I would say connect the two LEDS switch on and leave on for a while all the time checking incase the LM3914 gets hot... if it does get hot then disconnect and wire up using one LED... if it stays cool then you can use two LEDS...
I know this is a trial n error way of checking but without running through the entire circuit (wich takes alot of time) its hard to tell...

I think it'll be ok with two LEDS as it says in the data sheet the LM3914 is capable of running a low level lamp...

Hope this helps... i'll be striping mine down tonight and see if i can figure out how to wire it up

Franko

Thats a good idea Rich... but buzzers take up more current dont they? would anyone know how to wire up the buzzer? hmm it'll be worth looking into

Scott.T

iTrader: (2)

Use a low switching current relay