Electronics Workshop

Are you interested in working with or creating your own electronic devices? Would you like to dazzle your friends with blinky LEDs? Have an idea for an interactive art piece? Want to add some custom sensors to your home automation setup? Ever wonder how an ohmmeter or oscilloscope might help you? Then we have the series for you!

Every month, squidwrench will be hosting a monthly series on electronics. We started from very basic concepts, and we help folks build a solid foundation as we go along. These workshops aim to be very hands on. We will cover some concepts to establish an understanding, and then move into application and practice.

This session will cover transistors as switches, capacitors as charge storage elements, and how to not kill your microcontroller. Expect to learn about graphical load lines, power dissipation, energy storage, time constants, and blinky LEDs galore!

The details:

Transistors as switches

NPN transistor as "to ground" switch

• where to measure device voltages?
• passing mention of flyback diodes
• IB needed for saturation

Graphical parameters: saturation voltage and cutoff

• resistive load line: VR = VCC - VC
• power dissipation
  -secondary breakdown parabola

Darlington transistors

• extreme beta with higher VBE

PNP transistor as "from supply" switch

• why VCC must not exceed controller VDD
• kill microcontroller & logic

Wire up pulse gen to transistor

• base current
• collector resistor for LED
• oscilloscope to show voltages

Capacitor as charge-storage devices

C = Q/V, so C = ΔQ/ΔV, thus
i = C * Δv/Δt
energy = 1/2 * C * V²

Charging from a voltage source through a resistor

Exponential waveform: e^t/τ
time constant τ=RC
show 3τ = 5% and 5τ < 1%

Add cap to transistor switch with R

• charge vs discharge paths
• calculate time constants
• verify!

This is a lofty set of goals, so we may not make it through it all. If we don't, you're always welcomed to come ask questions at one of our Weekly Doings (every Tuesday at 7pm).

We have plans to cover everything we can including theory and math, practical use of instruments, various soldering and desoldering techniques, as well as design and (super small scale) manufacture of printed circuit boards. If you don't know what some of those words mean, come on out anyway and we'll get you up to speed!

We have some tools available for use, including meters, scopes, and soldering stations, so if you're brand new, just bring a notebook and a pencil. If you have your own tools and would like to be more proficient with them, feel free to bring those.