All posts by ASC

Plotting With Gnuplot And Parameter File

How do I set up Gnuplot so that the ouput will be safed to a file, what parameters influence the output.

#Title of the plotdes
set title “Verbrauchsdaten Strom und Gas”
#Title of the x-axis
set xlabel “Monat”
#Title of the y-axis
set ylabel “Strom-/Gasverbrauch in kWh”

#the x-axis is formatted as a date
set xdata time
#the data format for the x-axis data is “06/2006”
set timefmt “%m/%Y”
#the label of the x-axis shall be in the form of “Jun 06”
set format x “%b %y”
#the y-axis shall have 5 subdivisions of the main tics
set mytics 5
#on the x-axis only the months 07/2005 till 06/2006 shall be displayed
set xrange[“07/2005″:”06/2006”]
#the grid shall be behind the plotted data
set grid back
#the line width of the main grid shall be 2, of the sub grid 0,5
set grid mytics lw 2, lw .5
#for the x-axis no grid is displayed
set grid noxtics
#the data will be displayed as boxes which are 80% wide
set boxwidth 0.8 relative
#the boxes will be filled with a 25% intensity
set style fill solid .25
#the legend will be displayed left of the plot
set key left
#output to pdf file
set terminal pdf
#output file will be named “strom_und_gasverbrauch.pdf”
set output ‘strom_und_gasverbrauch.pdf’

#input data is in file “strom_und_gasverbrauch.csv”,
#for Gasverbrauch column 2 is x-axis and
# column 7 isy-axis
# in legend the plot will be described as ‘Gasverbrauch’,
# it will be display as box with color 3
# the second plot uses column 2 and 4 is labeled ‘Stromverbrauch’
# will be displayed as box and with color 1
plot\
‘strom_und_gasverbrauch.csv’ u 2:7 title ‘Gasverbrauch’ w boxes fs 3,\
‘strom_und_gasverbrauch.csv’ u 2:4 title ‘Stromverbrauch’ w boxes fs 1

Low-Cost 12V Fan Control With NE555

Fan control with a 555 timer ic for a PC enclosure fan.

In the enclosure of my PC is installed an additional fan. From that I removed immediately after purchase the supply voltage because of the noise it generated.

However. To achieve a lower temperature inside of  the computer case but to keep the noise level low I trew together some components from my electronic stuff box and build a fan control.

Platine Lüftersteuerung The core component is a NE555. The whole circuit is build on as grid-style PC board. But I did the desing in EAGLE just because it gives me the possibility to place the components on a defined grid and makes the routing easy.

The application circuit from the datasheet of the menufacturer was changed so that the discrete resistors were replaced by a potentiometer. The on-time of the generated PWM can thus be changed but the frequency of the PWM will not change.

The choise of the components was defined by availability in my stuff box. With the potentiometer of 50 kOhm and the capacitor of 0.33 µF the frequency of the PWM calculates with 1/f=0.63*R*C of about 100 Hz.
The output power of the NE555 is rather low, that’s why there is the transistor BC140 as an amplifier of the PWM. Because the signal is a PWM there is no need to consider the operating point of the amplifier. The resistor to the base of the transistor only limits the current to the base.

The connection of the fan is made by cutting the connection wire and placing the circuit between fan and its power supply. The electrical connection will be made by screw terminal that are placed on the board.

Img 0155 1A

Downloads for this article:
Eagle Board file, Eagle Schematic

Pwmboard-1 Pwmschematic