Jeff Duval and Palash Nandy
Get the Electronics 101 slides
Read Sparkfun’s electronics fundamentals
Here is what we are going to go over:
At the end of this you should be able to design the circuit needed for homework
The slides also cover op-amps and power electronics. Very useful for the outputs week
This book: Horowitz and Hill, is the bible for electronics.
Get EAGLE CAD (sparkfun’s setup instruction)
Read Sparkfun’s PCB Basics and How to Read a Schematic
We will cover with a live demo:
At the end of this part you should be able to create a millable file for your circuit
display none dimensioninto command box at the top to see outline.
display none topto see traces
See Jeff’s tutorial for more pointers
Q:Does the voltage divider (with two resistors) always provide the same voltage drop, regardless of the load/resistance on V_OUT? I suppose not, so how do we regulate this?
A 1):No. The rule of thumb here is to load the circuit with 10-20x more resistance. If you make your divider with 10k & 10k you shouldn't connect it to a load lower than say 100k.
A 2):Please note that even 10k & 10k is high for an ADC input. A cheap & simple trick is to place a small (say 10 or 100nF) cap in // with the lower resistor.
A 3):To keep this voltage independent of the load use a follower opamp
Q:Do we need 1 resistor per LED in parallel because otherwise, the current flow will be much higher in some LEDs than others (due to manufacturing variances, etc)? Or for some other reason?
A 1):Yes. If you look at the Current/Voltage curve of a diode (http://www.amperor.com/products/led/images/led_i_v_curve.jpg) you'll see that a slight voltage difference can create a huge difference in current.
A 2):What will happen if you // LEDs with only 1 resistor is that you'll destroy the one with the lowest voltage... then the second lowest... up to the point where they'll all be dead