Difference between revisions of "Circuit notes"

From Wikiid
Jump to: navigation, search
(Audio without DAC)
(Audio without DAC)
Line 43: Line 43:
== Audio without DAC ==
== Audio without DAC ==
[[Image:Arduino audio.png|right|200px]]
[[Image:Arduino audio.png|right|300px]]

Revision as of 19:29, 11 January 2009

Some miscellaneous analog & digital circuit notes:

Analog filter


The frequency at which the filter attenuates to half it's original power is:

f = 1 / ( 2 x pi x R x C )
f = frequency in Hz
R = resistance in Ohms
C = capacitance in Farads

According to Atmel - a 10 kohm resistor and a 100 nF capacitor produces a filter with a 1 kHz 'crossover' frequency?!? Evil Mad scientist labs suggest a 33 kohm resistor and a 22 uF capacitor.

To make a high-pass filter, swap the resistor and capacitor.

Variable Resistor


On my Arduino, I see numbers in the range ~90 to ~1020 returned from analogRead(0) depending on the position of the knob. It's very non-linear though.


Arduino switch.png

The resistor is needed to avoid shorting out the Arduino pin if it's programmed as an output by mistake.


Arduino LED.png

Minimal ATmega Circuit

Minimal ATmega.png

Audio without DAC

Arduino audio.png

WaveShield DAC datasheet

MCP4921/4922 datasheet

Hooking up a Relay

Relay arduino.png

Wikiid Pages relating to Arduino (edit)
Command line Arduino
Startup code for Arduino
Low level functions for Arduino
Putting data in flash on the Arduino
External resources for Arduino
Board schematics for Arduino
Misc notes: Circuit notes, Music notes, Stepper motors