Modding Knightrider/HDD meter

That is a superb idea, thanks all for your help. I'm off to buy some fiber... now if only I could get some gigabyte cards hmmm...

 

What is PSU that is written in the drawing of the circuit? And those X's, are those connection points (headers)?

Cant wait to make this circuit

 

Fab complete

Thanks for the great walk-thru Macro. I completed my first circuit over the weekend. I've been lurking here for a couple of months and wanted to say thanks to everyone else as well. Truly inspired mods and good discussion w/ lots of help.

FYI - here is an excellent walk-thru on PCB etching that I used (I know that Macro was going to author one but this worked for me)
Tonepad's photo-essay on PCBs There is also a photo-essay that covers the etch.

Also, reducing the image 25% did not work for me; created an image too small - I reduced to 33%. Haven't figured out the problem here as I used many different graphics programs to print from as well as scaling the images first to determine where the problem was.....

I got all of my components from allelectronics.com (see the useful links sticky)

(Pictures are from geocities so drag to address bar if they don't show and you really care.......)

Breadboard with Bloo (checking to see if I can read a circuit diagram - I'm a MechE; the only think I know about ElecE is you can't spell gEEk without the "Double-E"):


Finished circuit with 9V power - fiddled with VR1,2,3 to get proper effect; note red LEDs as I didn't want to scrap the expensive blue ones on my first attempt:


Dodgy soldering - well, at least it works. Radioshack 15W iron is junk. Got my eye on a nice butane one at Lowe's with a proper chisel tip:


ooh pretty lights - the wife thinks I am crazy. Akin's me to a moth as I am attracted to blinky things:

 

If I'm using the circuit with 10 BLUE LEDs instead of the red, do I need to change any resistors? My knowledge of circuits and components isn't very good so I'm a bit confused on how the voltage is limited to the leds in this circuit. Is it the IC that does it automatically? Or do we need to adjust it or change out other resistors if we used leds with a different forward voltage requirement?

Zap has been trying to help me with this (patient guy ). I think its the resistor R7 that determines it - but its set at 3.3k - the spec list says:

Vref out = 1.25 ( 1 + R2/R1) - no idea which resistors R2 and R1 are on Macromans circuit, however. And say our leds are 3.3V each - we want Vref out = 3.3v?

 

The circuit will work with blue leds as it is. No need to change it unless you have an overwhelming desire to do so.

 

Cool.

So Macroman, if I change the leds to say blue with 3.3fV rating or 3.7V it would not be a problem with the current circuit? (no pun intended).

Just to better my understanding, how much voltage and current is being supplied to each LED the way you have it set up?

Is that determined by the IC? Or by R7? Maybe you can explain it better so I can learn.

Thanks Macro!

 

I want to build the circuit, but there is something i dont understand in the setup:

you say that the tweaking of VR3 and VR2 must be done when power is off, but some lines below you say:

So?

 

Actually, if you let the circuit free run it is a lot easier to adjust.

You can do this by bypassing whatever you are using to sense the hard drive activity.

Adjust then remove the bypass...... don't have it hooked up to the Hard drive when you bypass it..... shouldn't be that big a deal, but doesn't hurt to be safe.

 

sorry but dont understand what bypassing means here. I can have psu connected but hdd disconnected? how o I simulate the hdd activity?

 

This circuit uses an optoisolator hooked up to the hard drive header.
This neat little piece of silicon gives you isolation between the motherboard and the Knightrider circuit. It also acts as a switch between pins 5 and 4..... pin 5 coming from a potential, and pin 4 going to a load.
To make your circuit free run just temporarily short pin 5 to pin 4 and the apply power.
adjust your circuit to the way you want, and then remove the short.

Just a note, to avoid any mishaps I would also disconnect from the mother board Hard Drive header while adjusting.

 

ok, just one more thing:

in the circuit scheme on bittch article the connection to the hard drive says "to HDD (2+ and 2-)...

Where do I plug it? to the mobo pin header that goes to the led? or is there a connector on the hdd that can directly go to a led (never noticed this).



thanx alot. I'll show your guidelines to my father. he's an expert.

 

Mobo HDD LED Header

 

okay! thanx alot!!! i've just bought all the components. i just cant find male connectors for 12v PSU power... (the small white ones). tink I'll have to grab them from an old pc card...

 

Good luck,
Take pictures......
It's always good to take pictures......
At least thats what they tell me.

 

hey here you are some pics... I had forgot this 3d... (sorry )


...so have opened a new one

http://forums.bit-tech.net/showthread.php?s=&threadid=35451


what do u think? (reply there)

ciao,
jack.

 

Variation

I was thinking about a variation of the Knightrider HDD meter...

What if the circuit were redesigned with a decoded counter IC? I'm picturing several LED's scattered throughout the case (I have a lot of plexiglass and lucite in my case). Every time there was disk activity the next LED would light resulting in flashes of light from all over the case during activity (lightning-like even with some high ccd whites). The problem is I have only a basic understanding of electronics. I think a 4017 or 4022 would work but I'm not sure how to properly drive the clk with the hdd led header (perhaps an opti-iso and a small capacity or driver?). Ideas anyone?

Here are the IC's I was looking at:
http://us.st.com/stonline/books/pdf/docs/8217.pdf
http://www.semiconductors.philips.com/acrobat/datasheets/74HC_HCT4017_CNV_2.pdf
http://eeshop.unl.edu/ds/CD4017BC.pdf

EDIT: Actually, I found the acrimonious chaser circuit here http://forums.bit-tech.net/showthread.php?s=&threadid=27158
It should be no problem adapting the "HDD switch" to this circuit. I'll send some pics if the project turns out.

 

It's a good Idea.
A 4017 would work, but I think the max current you can get from that chip is 25 miliamps at around 7 VDC for VCC (That means Supply Voltage). So, you don't want to use an LED that requires more than that. Fortunately most discrete LED's are 20 miliamps, and the voltage required varies with type and color, so you will end up having to use a resistor for each LED to control that....... bit-tech has a good calculator for the resistance value.

There are tons of circuit diagrams out on the net that can show you how to wire this up. Most of them use a 555 as a timer. All you would have to do is use the HDD header as an input to your clock for the 4017.

Anyway,
I've used this chip before for other things, If you need help I'm glad to.

 

I could be wrong about the current capacity of that chip, but even if I am you can use a driver chip on the outputs to drive your LED's

 

Thanks for the help... I wasn't sure if the hdd header would work as a clock input, I'm glad it will. How does this sound?...

- Take the chaser circuit and adjust the resistors for 12VDC input instead of 9VDC.

- Replace the 555 clock and use the opto-isolated hdd input from the Knight Rider circuit.

- I found some nice 6000 mcd LED's... (http://www.allelectronics.com/spec/LED-94.pdf). They are 1.94V / 20mA so the 4017 should work.

I'll post a circuit before I start to make sure I've got this right (and in case anyone else wants to try this)

 

It should work..... don't forget to take pictures