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Discussion Starter · #1 ·
I just ordered a Delta 410 for my HTPC and a new 5x125w power amp. After some reading here at the forum I got the idea to build my own volume wheel for controlling the master volume.


Have anyone tried anything like this?


I have seen many case modes using a wheel for controlling the fan speed, but this is probably a little more complicated. What I need is first a wheel and then some device sending commands to a serial port and witch is read by girder plug-in.


Does anyone know how to build such a device which reads the movement of a wheel and then sends some signal. Maybe a variable resistor could be used and something to read the changes in the power on the other side?


That solution seams pretty complicated and expensive maybe there is a cheaper one.
 

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i remember seeing one a while ago that was exactly that, a big nob you could put in front & it ran through a USB port. It was neat but i can't remember where i saw it, but it does exist.
 

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Discussion Starter · #4 ·
This seams like the right thing but still pretty advanced...


Variable Resistors

When you want to measure varying amounts (analog measurement) of energy in the physical world, one of the easiest ways is to use variable resistors. Resistance is the measure of how easy it is for current to flow through a circuit. Suppose you want to know how hard someone is pressing down with their thumb on a picture on the wall. You would find something to convert the pressure from the thumb into an electrical resitance, a force sensative resistor. You would put the force sensative resistor under the picture on the wall and send a current to the resistor and depending on how much current flows through, you know how hard the person was pressing. To measure how much current came back, you will need a mircorcontroler with A/D conversion capabilities. After you decide on your variable resistor you will want to install it into a analog input circuit with your microcontroller. You would then program your microcontroller to watch the variable resistor and perhaps program your authoring software to react to the microcontroller using serial communication.

http://fargo.itp.tsoa.nyu.edu/~dano/...l/transdu.html
 

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You could use a potentiometer (standard variable resistor)

together with a 555 timer IC to generate different digital

signals depending on the resistance dialed on the

potentiometer. This digital signal would be fed to the

serial port and read by the software driver to chose the

desired volume.


HobbieMan
 

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Discussion Starter · #7 ·
_HobbieMan


Have you tried to build something like this?

And can you please describe how an 555 timer IC work?



_NickB


I need a Black wheel and the Griffin doesn't seam to have any good ways to mount it on the case.
 

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I believe that HobbieMan is referring to an astable multivibrator based on the 555 timer IC (here's a quick link: http://webhome.idirect.com/~jadams/e...555astable.htm ). The frequency of the pulses that the circuit produces is a product of the ratio between two resistors and a capacitor. If you replace one of the fixed resistors with a potentiometer, you can vary the pulse train (say 1Hz = 0% volume and 1kHz = 100% volume). You could interface it an unused serial port but you'd still have to write a program to poll the port and interpret assigned events (control Winamp, etc.)


Actually, you don't even need a 555 timer IC -- a couple of transistors, a handful of resistors and a capacitor are all you need -- you can find the info on serial port interfaces on the Net.
 

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Yes, a long, long time ago, I built a similar circuit.


Just like _ajira99_ mentioned, the frequency of the generated

signal is proportional to the resistance and capacitance of

the components used. Anyway... I believe RadioShack has a small

and inexpensive 555 timer projects book that you can use to build

what I have suggested. Or you can go on the net and find it.


HobbieMan
 

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I bought the Griffin Wheel myself, and I have to say that it is really well built, and definitely worth the money. I plan on mounting it so that the wheel itself is sticking out of the fascia of my case. It is a wheel/push button and has built-in blue LEDs that dim


I'm hoping that they will relese an API so that I can integrate the wheel as a controller for my VFD-based menu system.
 

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Sure if you dont actually want it on the case Girder will put volume control into any IR remote for you..
 

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Well, I bought the griffen volume knob and am going to integrate it into the front of my new HTPC facia. I'll let you know how it works.


Wes
 

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Discussion Starter · #14 ·
_Mooneyass


That would be great, maybe I could spary paint it black.


_phunge


Is the USB connector located under or on the side of the wheel?
 

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Two simple ideas off the top of my head: 1) Gameports are designed to read pots directly (actually up to 4 pots I believe), so just a little code would do the trick I would think. 2) Use a rotary encoder which looks and acts like a pot, but outputs digital codes which could easily be read via a serial port. (I would use google to search like "rotary encoder" and " serial port", as I'm sure someone must have done this already).


Zarcov
 

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Discussion Starter · #18 ·
Quote:
Originally posted by Mooneyass
AndreasB


I'm trying to find out how to lock my DVD at 2x. How did you do it? Can you point me in the right direction?


Wes
Pioneer has a dvd utility where you can select preferred speed. But it only works with some of dvd-roms with the newest firmware.
 

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Regarding the Powermate...


The USB cable comes out of the side of the unit, right near the base. I could probably post a picture, if you like. If you were going to mount it, you would want to do so such that the base was behind the fascia, and only the wheel was sticking out.
 
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