Electronics notes/Bluetooth notes

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This is for beginners and very much by a beginner.

It's intended to get an intuitive overview for hobbyist needs. It may get you started, but to be able to do anything remotely clever, follow a proper course or read a good book.

Some basics and reference: Volts, amps, energy, power · Ground · batteries · resistors · changing voltage · transistors · fuses · diodes · varistors · capacitors · inductors · transformers · baluns · amplifier notes · frequency generation · skin effect

And some more applied stuff:

IO: Input and output pins · wired local IO wired local-ish IO · · · · Shorter-range wireless (IR, ISM RF, RFID) · bluetooth · 802.15 (including zigbee) · 802.11 (WiFi) · cell phone

Sensors: General sensor notes, voltage and current sensing · Knobs and dials · Pressure sensing · Temperature sensing · humidity sensing · Light sensing · Movement sensing · Capacitive sensing · Touch screen notes

Actuators: General actuator notes, circuit protection · Motors and servos · Solenoids

Some stuff I've messed with: Avrusb500v2 · GPS · Hilo GPRS · JY-MCU · DMX · Thermal printer ·

Audio notes: microphones · device voltage and impedance, audio and otherwise · amps and speakers · basic audio hacks · digital audio ·

Less sorted: Common terms, useful basics, soldering · Arduino and AVR notes · ESP series notes · PLL · signal reflection · pulse modulation · electricity and humans · resource metering · Microcontroller and computer platforms · SDR · Unsorted stuff

See also Category:Electronics.

Bluetooth works in 2.4 - 2.4835 GHz, in 79 separate 1Mhz channels

Bluetooth continuously hops channels, to lessen the probaility of consistent interference with other devices and other protocols (in particular 2.4GHz WiFi). Busy areas still have congestion problems, though.

This article/section is a stub — probably a pile of half-sorted notes, is not well-checked so may have incorrect bits. (Feel free to ignore, fix, or tell me)

Versions and speed

Maximum speed:

  • Bluetooth 1.1 and 1.2 versions is 1mbit in theory, ~700Kbit/s in practice
  • Bluetooth 2.2 can reach ~1 to 3Mbit,
  • Bluetooth 3 HS can do ~24mbit in theory, 3 plain is still ~3MBps
  • Bluetooth 4 didn't really change speed(verify), but changed low power details


Range is primarily a function of output power, and is either:

Class 2: ~9m, which is what many portable devices do (PDAs and in particular most headsets) (...which is arguably primarily helpful, both to limit collision/congestion, and to limit power use)

Class 1: Up to ~100m, though in practice it may be more like ~30m. Dongles may well be class 1