PC Modifications.

See general Picture Gallery.

At the end of 2002, I became aware of the trend to modify one's computer case. I have no specific desire to make a fancy computer case. I will however make a few changes, so it will match my choice of colors.

I have collected a Picture Gallery of other pc-mods that I find inspiring and educational. One day I may make my own suitcase or toolbox pc.

For now I just want to silence the computers I have running. Also I want to have easier control over the power consumption of the computer. And especially the peripherals, now that USB is catching on.

To silence my pc's I have done the following:

• installed one or more extra fans,
• and added a miniature trim potentiometer of 470 ohm to each fan, so I can turn the RPMs down, and thus eliminate the fan noise.
• hung the hard drives in rubber suspension, so no vibrations reach the cabinet.
• added some padding foam to eliminate the whine from the hard drives.

To enhance the functionality of the computer surroundings I have:

• painted some of the case, and some of the keyboard in a transparent Ice Blue color.
• changed the ON indicator light to Blue
• added a USB connector to the front side of the cabinet frame.
• added a LCD thermometer to easy monitor the case temperature
• made an external power connector with 5V and 12V.
• I plan to add a 6V and a 15V option, so I can run low-power consuming devices from the Computer power supply. Currently I need 6V for USB hubs, and 15V for an external Mikrotek USB scanner.
• added some Velcro to the outside of the case, so USB devices can easily be organized around the case or the monitor.
• made attachments for a special screwdriver kit and penlight flashlight, so they are always handy at the back of the case.

BLUE LED voltage step-up.

This is the schematic of the complete circuitry you need for a step-up power switch for LEDs
	The trim pot. can be 470 ohm. The 10K ohm resistor is to protect the transistor.

If you want a more precise value of the trim potentiometer then you need to decide how many milli amps (mA) you want going through the led, and then do a simple calculation. The transistor uses 1.2 Volt, this leaves 3.8V between the LED and the Trim.

The tables below show how many milliAmps you get by applying a certain voltage over the different kinds of LED. If we thoose the Bright Blue LED as our example, and we want 3.3mA worth of light. It needs 2.8V, leaving 1V for the Trim.  From Ohms Law U=R*I  and  R=U/I we find: 1V/3.3mA = 1/0.0033 = 303 Ohm I have calculated the Ohms needed for each of the measurements in the tables below, so you can see for your self, the interval you need for the Trim resistor. Trim Resistor Ohm is found by applying this formula: (SupplyVoltage-(1.2+voltage over LED))/mA in LED = T.ohm Below are the results of some measurements I made, on the different LED I had in my drawer.

	This illustrates what is the positive and the negative side of a LED. I remember it by thinking of the flat side of a battery, as it has the same value as the flat side of a LED.

External Power

I do not run any over clocking, and I have measured the pc's to currently use less than 30Watts, this should leave plenty power to run some of the peripherals from the pc power supply. It is a 200Watts standard power supply, and even though it may not be able to deliver all of that much power, I think I can at least get some 75% of the listed max. Amps.

Using a D-sub9 female connector (to make it different from the serial port) I now run my External IOmega CD-burner using this power source.
I have also added mini-jack connectors for 12V and I will later add mini-jack connectors for 6V external power.

One of the added bonuses I get from using the pc power supply for external boxes is that I can now unplug all those little transformers that seems to be colleting in greater and greater numbers. My last count reached 16 such transformers.

And each of them draw current, even when the device is turned off. That is right, since they are transformers they stay connected even when you turn your pc or the device off. Using 5-15 watts each 24 hours a day, weather you are using the device or not. With 16 devices each using an average of 10 watts, that is 160 watts an hour! Or 3.8KWh a day, which adds up to some 1400 kWh a year.

IOMega External Power. Red 12V, Blue 5V, Black GND