Difference between revisions of "ElectronicsClass"

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= Links and class notes =
**[ How bipolar junction transistors actually work]

Revision as of 18:36, 28 July 2010

Electronics Class

This class is targeted at the beginner who wants to learn electronics. It would make a fine prerequisite to the Microcontroller Course or the HAMClass


These images form a slide show and a gestalt introduction to electronics. In which we map the techniques available to hackers and their surrounding requisite building blocks.

My hacking started with music and production. it wasn't exacly the tech; more for the ride.

  • [[2]] WMUC main studio

Complicated behaviour arises from iteration of simple models. Learning how to operate something like this is simpler and more subtle than it looks.

  • [[3]] wheatstone broadcast console

Easier to see is block diagram form; a gestural view of a complex system. WMUC recording suites and broadcast control rooms. Computing.

  • [[4]] signal diagram

Why study DC/baseband/RF electronics; anachronism?

  • [[5]] chill on the roof.

Space shuttle shots; APRS , RACES, field day. Social technical effects require proficiency.

  • [[6]] W3EAX tower

Small systems scale into big ones. 40,000 people at Operation ceasefire (united for peace& justice) '05 at the national mall. Standing between SS, Park police and thousands of protesters.

  • [[7]] ceasefire stage
  • [[8]] ceasefire 40k

No always smooth sailing.

  • [[9]] mars needs bolts

Building whimsey.

  • [[10]] lightup dance floor

Computer control over physical objects. microcontrollers + christmas tree lights.

  • [[11]] dance floor controller

Not always smooth. Electrical compatibility != political compatability

  • [[12]] hhr - phear the transaxle

More small systems iterated.

  • [[13]] fireworks diagram

DIY Ignition source in Berlin. in a pinch you don't need a parts catalog.

  • [[14]] igniter controller

Apologies to Dakami

  • [[15]] fireworks crates

Simple systems, RC control, Robots and igniters.

  • [[16]] wm greek fire

Recently robotics have become accessible to experimenters. Bluto cuts, welds and hugs.

  • [[17]] Welding robots!

Required Materials

(see also: our Suppliers page)

Digital Multimeter.jpgAnalog Multimeter.jpg

Soldering iron.jpg



  • wire 24ga

  • 30ga solid core wire

  • Resistors 10kohm

  • variable resistor 10kohm linear $1

  • leds (various)

  • capacitor 470uf (ish) [[19]]

  • pn2222 transistor $.03

  • 1/8 male phono jack
Read The Fine Data Sheet:  They hide secrets in the documentation.


There are many like it but this one is mine.
  • Naming of parts
  • Should be a VOM - Volt Ohm Meter
    • metering modes
      • restistance - Ohms of resistance
      • voltage - Volts
      • Current - Amps/Milliamps - check the leads
      • diode check - see [Diodes]
    • leads - plugged into the right ports?
  • Continuity testing
    • set the meter to the lowest resistance mode (200ohms or auto resistance)
    • or perhaps Diode check; or even beeping
    • reads "off scale" when the leads are unconnected, this is an open circuit
    • firmly touch leads together -loopback test
    • reads near 0 if the leads are crossed
  • Voltage testing
    • set meter to 20Vdc or VautoDC
    • touch leads to metered points
    • the reading on the meter is the difference in voltages between the leads
    • Try AC mains!! - safety second.


  • use the continuity meter to diagram the electrical layout of the switch.
  • solder switch to the board.
  • test under power with meter voltage setting



  • SPDT - single pole dual throw
  • DPST - dual pole single throw
  • 4P10T - ???
- Map this mystery switchLab


The basic wire is a pipe through which electrons can flow from the lowest voltage side to the highest (conventional current) up to the physical limits of the wire.

  • Condunctor vs. Insulators
  • Current limit via wire gauge [20]
  • Voltage limit via insulation.
  • Magnetic and Electric fields surround an energized wire (what?!)
  • And wire will respond with current when moved through magnetic flux
    • bass pickups
    • Lentz law
    • Siemens, mho, ohms
  • strip wire
  • and don't nick the conductor


  • Einstein's "spukhafte Fernwirkung"
  • Quantum Electrodynamics
    • Electron and photons interact - somehow
  • Gauss, Maxwell and
  • Permanent magnets useful - locked domains
    • Ferro materials, Ni, Co, Sr, Rb, Nb, Nd, Cr and Fe.
    • Except when they aren't - curie temperature.
  • Hall effect - sensing - spaceship drives
  • Motors, linear, rotary, vibrational, direct ( magnetohydrodynamic)
  • Radios
    • EM probe demo
    • EM spectrum
      • DC, ELF, SLF (submarines, blue whales), AF, LF,HF, (Short wave), VHF, UHF, Microwave, weird stuff, gamma rays (the incredible hulk, gian ants).


Hold the cold end.

Soldering ( for our purposes ) is the process of joining electrical contacts with a low melting point metal to make a mechanically and electrically strong connection.

  • Restrain long hair/clothing/jewelry.
  • Clean both parts of waxes, oils or debris.
    • Ethanol/Methanol/SLX
    • Flux/Rosin/Dry
  • Mechanically fit connections together
  • Clean and wet the iron
    • Tip should be immaculate and bright
  • Heat both parts until hot
    • Cheat, use another heating element
      • quartz floodlight, sterno, propane or mean stare.
    • but not too hot - see blue smoke lab
  • Apply just enough solder to wet the contact surfaces
  • Wait for the connection to shine smoothly
  • remove the iron an test the connection
    • yes it's hot stupid.
    • the meter should find near 0 ohms of resistance between the two parts even when mechanically stressed.
    • the meter should read "off scale" to everything that should be isolated
  • Splice practice
    • Western Union Splice
    • Pigtail Splice

Speakermaking lab


  • junk wire, lots of it
  • magnet ( stronger is better )

Test stuff:

  • multimeter
  • signal generator, (or music source)
  • power amp


  • Make coil of wire 24ga 1" dia, 50-400 turns.
    • use a form, marker, tp tube, pvc pipe
    • Measure impedance > 1.5 ohm
  • Stick coil of wire to diaphram
  • Make stator/armature
    • stick magnet to something - not too ferrous
  • stick diaphram near armature (correct axis??)
  • connect to amplifier; apply Rock!

Exercises for suckers:

  • Use the lentz law to calculate the force generated by thingy.
  • Why 8ohm speakers in the house?


Not like the NYC variety

Resistors impede the flow of electrons across them; usually to protect components from excessive current.


  • solder resistors, meter and record;
  • compare to ohms law math

Get this out of the way early (and often)
  • turn off the switch
  • Solder the 30ga wire ends on to the lab 0 area
  • stow fingers away from wire
  • turn on switch


  • Measured in watts (usally)
* .01w laser pointer
* .25w cell phone
* 1w 
* 15w car stereo
* 25w soldering iron
* 100w light bulb
* 1500w hair dryer
* 200 horsepower (750w/hp)
* 3 tons of Air conditioner capacity (3.5kw/ton)
  • The notion of instant work
  • Energy or work is expressed in joules (watt*second). Or perhaps (Kw*H)
  • Power(watts) = Current (Amps) * Volts

Electromechanical relay is a switch that's controlled electrically.


  • Easy to design for
  • debugging (listen for satisfying click)
  • excelent isolation
  • high power control/$


  • high drive current (mostly)
  • noisy (mostly)
  • slow
  • moving parts (eeew)

a typical relay - map this mystery relay lab



  • a favorite led [21]
  • LED ( Light emitting diode ) are diodes with a clear case.
  • electrons only permitted to flow in one direction: cathode to anode
    • there are exceptions [diode breakdown voltage]
  • discontinuous IV curve
  • diode logic
  • the cathode is marked
  • the diode check function of the meter can reveal the correct polarity of a mystery diode with a suspect cathode mark.

Light Emitting Diode

  • the short lead is the cathode
  • LED's need current limiting (see BlueSmokeLab)
  • solder in 1kOhm resistor for the led , although you may use another if you can justify the value
  • Solder in the LED, with the short lead towards the ground.


Printed Circuits


470μf electrolytic cap


wikipedia capacitor <math>\operator {work} (V) = \frac {1}{2} 2)Cv^2 </math> Hmm.. no teX support here.


  • Filters
    • Decoupling - Ripple rejection
    • Blocking - DC Bias rejection
    • Use in networks - equalization networks
  • Storage
    • Pump and dump - Photoflash.
    • Tank application - DC - DC converters
  • Esoteric
    • Sensors - Strain gauge
    • Microphones - Old school
    • nonlinear math - Calculating logs/exponents.


PN2222 N channel transistor

little amplifierlab

  • class A amp
  • DC blocking caps
  • bias resistors
  • fixed gain
  • inverted waveform

construction intro

  • breadboard intro
  • soldering intro
  • led circuit

Digital Logic

  • AND C = A & B
  • OR C = A | B
  • NOT C = !A
  • NOR C = !(A|B)
  • NAND C = !(A&B)
  • MUX C = select A(n) based on B(n)


LM386 Audio Amplifier [22]

Links and class notes