electronics

Oscillators:

Table 1. Performance Comparison of Clock Source Types (Source: http://www.maxim-ic.com/appnotes.cfm/an_pk/2154)

Good Design Practices

 Analog

- When doing a highly sensitive first order RC filter, put half of the capacitance near the source, and the other half near the micro. This cap near the source helps remove some of the higher-order harmonics from introducing noise to your PCB, while the cap near the micro finishes the filtering in addition to cleaning up residual noise from PCB lines.

- Separate power/ground for analog/digital

FILTERS

 High Pass Filter: F=1/(2*pi*R*C) 

 Low Pass Filter: F=1/(2*pi*R*C) 

Digital

- When connecting to an external device (any wiring assembly)
    Outputs: Place 100 ohm resistor near the microcontroller. Current limiting, helps prevent surges
        (capacitance in the PCB, inductance in the lines, ect)
    Inputs: Place 100 ohm resistor near the connector. This prevents it from acting like an antenna and
        introducing noise into your circuit.

 -Charlieplexing: n drive pins can be used to control n^2-n LEDs

 MOSFET Pin names

 Project Ideas

Taken from http://laser.physics.sunysb.edu/~tanya/report2/

For better information: http://www.robotroom.com/ReversedLED.html

Mouser
Blue: 2200mcd, $.29, WP7113QBC/D
Red: 6000 mcd, $.35, HLMP-C008-U0000
Green: 1000 mcd, $.79, WP7113MGC
Yellow: 5000 mcd, $0.54, SLI-580YT3F
Orange:7000 mcd, $.59 WP7104SEC/J
Cost: 2.56
Op-amp:

Digikey:
Blue, 3800mcd, $.66, OVLGB0C6B9
Red, 8550mcd, $.21, OVLGS0C8B9
Green: 6000mcd, $.92, LTL-353TGK
Yellow: 10300mcd, $.21, OVLGY0C9B9
Orange: 2500mcd, $.23, WP7113SEC
Cost: 2.23
1MHz rail-rail Op-Amp: $.72, MCP6004-I/P-ND

 USB Information

http://www.beyondlogic.org/usbnutshell/usb1.htm

Other Websites

All Electronics: Surplus electronics equipment.

Miscellaneous

 Component Choices:

Capacitors
- Metal can capacitors cannot do higher frequencies because of eddy currents
- Dry-film capacitors can only handle up to 250V before the corona  effect kills them
- Oil-filled capacitors can handle higher voltages (up to 600V) before the corona effect occurs
- oil-filled caps are usually metal can
- Steel caps cannot handle as much current as aluminum caps

Resistors
- Wire wound resistors can handle up to 10x their rated power for a limited amount of time

MOSFETS (General TO-xxx packages)
- A package can handle 1/10 of the rated wattage without a heatsink. Datasheets assume an infinite heatsink.

 Decoupling Capacitors
-All decoupling capacitors have an associated inductance and resistance. The inductance of standard packages can be seen below along with its resonant frequency for a .1uF and a .01uF capacitor (Source: http://www.avx.com/docs/techinfo/parasitc.pdf)

 -If you want good decoupling, you should use a .1uF cap in an 0805 package and a .01uF cap in a 0603 package (place the smaller cap nearer to the device). Just make the bigger cap fit in a bigger package than the smaller cap.