Electronics Acrimonius: QTouch Circuit and Fan Rpm Sig to 10Led Bargraph...

Hello all...

This is directed to all electronic guru's (ZAP - have not forgotten ya mate, that mediaPC is looking damn fine , Linear, Macro) but specially Acrimonius!....

PART ONE- Qtouch.
-----------------------

http://www.qprox.com/downloads/d/qt113_102_datasheet.pdf

After going through the chip's documentation, I figured I'll wire the QT113-D like so:

5V source to pin1, 3, 4 and 5 giving an infinite gain and response time of 10ms. VSS (pin 8) goes to ground, and pin 6 connects to 7 via a 10nF cap and together to the electrode (metal)...

Now I was thinking of having this:

same 5v source ------/\/\/\/\---|>|----OUT (pin 2)

basically a current limiting resistor (if the LED is not a 5V ultrabright - which is my case it will be, so no resistor)....and the led with the cathode connected to OUT...

Now, how do I get OUT to act like an SPST so I can connect it to the PWR Header on the mobo?

PART TWO
-------------

Rpm signal to 10led bargraph.

I do relized that this needs the use of LM3914 (linear) and the yellow rpm wire....

Think you could sketch me up some schematics pls?

Thanks, Mike

 

In reply to you first question:
In section 2.2.1 of the spec sheet it says that the DC output will remain LOW as long as you are touching the sensor plate.

This means you can direclty use this to power on the PC, as the Header on the motherboard uses and ACTIVE LOW signal.

Connect the output of the QPRox directly to the header pin on the motherboard, and follow the sample schematic in figure 1-1 of the spec sheet.

The other pin on the header on the motherboard is just ground, so you can ignore it. (As long as your QPRox uses a common ground with your PSU)

 

On the bargraph; don't use the yellow RPM wire; put the bargraph circuit with an appropriate circuit IN PARALLEL with the fan to measure the voltage ACROSS it.

 

The LM3914 is a analog voltage level - to bargraph converter, so it wont work on the RPM Sensor

If you want to use the RPM sensor you would need a Timed Counter Circuit. It would have to count the number of pulses per second (Active low pulses) and then convert that to a graph.

 

Ahh acrimon, and zap!

Thanks Zap...

what was confusing me about qtouch is what Linear has in project logs, where he has a 14pin chip next to the qtouch chip so I thought more was needed....odd and it's not an optoisolator cause that's 6pins...

Acro, thanks, this way I can use the LM3914, instead of doing what Zap says which is more complicated IMO....

thanks!

Mike...

 

A possible SPST solution is to use an opto isolator; linear did a good intro to these in his 'IC Workshop'




I'd wire your bargraph like this if i were you, the SPEED CONTROL could be a potentometer or an optoisolator or a digital pot or whatever your planning to use. The are several practical examples of this circuit in my Advanced Fan Controller Reference guide.

 

Woah, Thanks acrim...

Actually I might use an optoisolator, but then I would connect the OUT from the qtouch to the collector, emmiter to ground, and the LED (pin 1/2) to the pwr header ???

Um, did you pay for livewire ?? Love it....how can I get the full thing...(I'm poor hint)

Thanks Mike...

 

I payed for it,worth every penny too.

Maplin:
Livewire Student Edition: order code: N29AJ. price: £24.99
PCB Wizard 3 Student Edition: order code: N31AJ. price: £24.99

 

ahh thanks, very cool....but answer my previous when you got some time pls:

"Actually I might use an optoisolator, but then I would connect the OUT from the qtouch to the collector, emmiter to ground, and the LED (pin 1/2) to the pwr header ???"

Thanks a million, your ACE!

Mike...

 

No, you want the circuit/IC to switch on the LED to activate the phototransistor, the collector and emmiter conect to the Power Header. Its shown on that diagram, have another look at the bit at the top.

 

Ahh sweet, it all makes sense now..sweeet

do all of 'em Opto's support 5V for the LED, and is there any current limiting it may need?

thanks,

Mike

 

I pushed 12v Through one of them once; 5v should be fine at a low current, allthough a 200Ohm resistor for peace of mind is allways good practice.

 

Ohh another use just hit me. what if I want to use this to work the 'eject' switches on my CDRW and DVDROM ???

I know that there will have to be a 'flexible' lead running from the 'unit' to the 'stealthed plate' (this will be the electrode...hehe') and that when it closes that it must not catch...but, other than this...does anything have to be altered?

Thanks,

Mike...

 

damn your quick, but thanks

how do you know which leg of the pwr header is ground? I mean, mobo man does not state....?

thanks, Mike...

 

Well you just use an optoisolator with the phototransistor instead of the eject switch and the LED side on the output from the IC.

 

Check out my Re-wired DVD Activity LED and Eject switch -Guide

Using the Audio Header is optional, it just makes it very clean.

 

Ahh thanks ZAP..actually I was going to use that as a guide...

hey your the man to ask this...

If you jamm the drive tray...how do you fix it...

I.e. press eject and the tray gets stuck....

got any pics of the internals...ect? And what 'stop' must one shove to remove the tray?

Thanks, Mike

 

clean, very true, but the problem still exists given that when the tray pops out the catode to PCB lead will need to be pulled (some give the length of the tray...

(2) this wire should remain hidden...

(3)...should not jam the drive..hrm...

A: remove the tray, and drill a hole the length of the tray and have some excess wire inside the drive...

B: instead of using the stealth panel as the electrode (because if there is another drive on top...then they will both eject... : PAIN!!
using another part of the case will mean I will use the audio connector

Mike...

 

Why does he talk about using a relay when it's easier to do it this way acromonious?

Thanks a million dude!

Mike..

 

LOL, no probs