Thursday, June 29, 2006

Tiny Threads - Tiny Multitasking Threads for Microcontrollers

by: Regulus Berdin
Limitations:
  • Maximum 254 lines per thread.
  • Thread context switching will not work within a switch block.
Usage example:
     TT_DEF(1)
{
TT_BEGIN(1);
while (1)
{
...
TT_SWITCH(1);
...
...
TT_WAIT_UNTIL(1,keypress);
}
TT_END(1);
}

TT_DEF(LED_TASK)
{
TT_BEGIN(LED_TASK);
while (1)
{
LedOn();
delay=DELAY_1_SECOND;
TT_WAIT_UNTIL(LED_TASK,delay==0);
LedOff();
delay=DELAY_1_SECOND;
TT_WAIT_UNTIL(LED_TASK,delay==0);
}
TT_END(LED_TASK);
}

void main(void)
{
...
...
while(1)
{
TT_SCHED(1);
TT_SCHED(LED_TASK);
}
}


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Wednesday, June 28, 2006

LED Circuits

LOW BATTERY VOLTAGE FLASHER (9) (undervol)
This circuit is designed to monitor two alkaline cells (3v) that from the battery often used in portable electronic equipment. It use an inexpensive IC from Panasonic that is connected to an efficient LED flashing circuit. When the battery voltage drops below a certain point the circuit flashes the LED. In the off state the circuit draws only 1uA, while in the active flashing state it draws 20uA. Published in EDN, Jan 2, 1997

FLASHING LED POWER INDICATOR DRAWS LOW CURRENT (18) (3vledfs1)
This circuit flashes a power indicator LED to keep the average current low.

1.5V LED FLASHER VERSION A (23) (ac14fls)
Many published circuits that flash LEDs need 3 volts or more. This circuit uses only a single inexpensive C-MOS IC and flashes the LED for a full year on a single 1.5 volt AA alkaline battery cell. The circuit uses a charge pump technique to provide the LED the needed voltage.

1.5V LED FLASHER VERSION B (24) (1vled3)
To squeeze even more energy from a alkaline battery cell, this circuit adds two transistors to a circuit similar to the above design to boost the efficiency. A small 1.5 volt alkaline N cell should flash the LED for a full year. It too uses a "charge pump" technique to provide a LED the needed voltage.

2 LINE TELEPHONE LINE STATUS INDICATOR (46) (2phostat)
Many home businesses use multiple phone lines. This circuit gives you a visual indication when a line is in operation. The two AA battery cells should provide enough power for about one year of operation. The circuit is line polarity insensitive...

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Monday, June 26, 2006

Bowden's Hobby Circuits

A small collection of electronic circuits for the hobbyist or student. Site includes over 100 circuit diagrams, links to related sites, commercial kits and projects, newsgroups and educational areas. Most of the circuits can be built with common components available from Radio Shack or salvaged from scrap electronic equipment. Most all of the circuits have been built and tested and believed to perform as described, however possible mistakes may be found.


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Sunday, June 25, 2006

Magnetic Levitation Schematic

Why Build a Magnetic Levitation Device?

Wacko Sales Pitch

Want to amaze and impress your friends?

Can something be held in mid-air with nothing touching it?

Do flying saucers use electrogravitics?

How does a maglev vehicle work?

Need a super accurate force/weight measurement?

Want to measure small changes in gravity?

Who says gravity cannot be beaten?

Want to see a simple coil levitate a steel ball in a magnetic field?

As long as you're building a coilgun, and have: magnet wire, power supply, breadboard, voltmeter, resistors and capacitors, switches, hookup wire, and other miscellaneous parts, why not?!

Maglev for Science Fair

I started this project with my 2nd grade son for a science project. The science fair was on March 16th, 1999, at an elementary school in Washington state. This was a fair, not a competition, where the emphasis is on having fun. Most sane parents would not design a closed-loop feedback control system with a second-grader, but as it turned out we didn't enter the project in the fair after all. It didn't work quite well enough, and the coil would overheat after a few minutes.

The benefits of doing this project were many, but not where I expected. I somehow expected to relate some ideas about electronic design. In reality the benefits were probably of more lasting effect. I worked together with my 7-year old and we had a great time. This was a chance for him to cut boards with a saw, drill holes, handle a screwdriver, measure and mark with a square, cut wires, and plug in chips and resistors. We handled parts, learned their names and looked at their symbols in schematics.

Some other things we accomplished were:
- To play with a cool gadget that we made ourselves.
- To experiment with magnetism, and see and feel how it works.
- To be challenged by designing a closed-loop control system.
- To use what I learned from my first coilgun, and learn more that might help with my next one.
- To refresh my knowledge of op-amps and analog circuits.
- To use up part of a mile of 24ga magnet wire.
- To buy new tools, in this case a dual-tracking 30v 5a lab bench power supply bought cheap at an auction.
- To learn how IR emitters and phototransistors work.
- To help fill my garage with electromagnet toys...

Schematic diagram of LED emitter, optodetector, amplifier and coil driver

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Circuit Schematic Symbols

The schematics symbols for most major electrical components can be found in this table. However, each component may have numerous possible representations. In cases where there is more than one common symbol we have tried to give an alternate representation.
COMPONENT SYMBOL ALTERNATE
Ammeter
[Schematic Symbol]
And Gate
[Schematic Symbol]
Antenna, Balanced
[Schematic Symbol]
Antenna, General
[Schematic Symbol]
[Schematic Symbol]
Antenna, Loop, Shielded
[Schematic Symbol]
Antenna, Loop, Unshielded
[Schematic Symbol]
Antenna, Unbalanced
[Schematic Symbol]
[Schematic Symbol]
Attenuator, Fixed
[Schematic Symbol]
Attenuator, Variable ...

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Thursday, June 22, 2006

Games and fun stuff (schematics)

  • Visor cradle serial interface
  • Electronic coin tosser
  • Electronic craps game
  • First response monitor
  • VCR ping pong game
  • Video ping pong game
  • MBC5/CPLD for the GameBoy
  • GameBoy Camera Parallel Port Interface
  • PSX controler to PC MIDI converter
  • Dreamcast PC serial adapter
  • GameBoy Cart Programmer
  • Memory game
  • 32 Kb x 8 emulator for the GameBoy
  • Project: NES to Atari 2600 controller interface
  • Battery Meter for Pinball Machines
  • SRX1 (Stephane's Robotic eXperiment 1)
  • Pine Racecar Victory Judge
  • Interfacing Sony control stick to Empeg
  • Electronic Nicad glow plug driver
  • April Fools LEDs
  • Pinewood Derby logic
  • Quiz Master
  • GameBoy Schematic
  • GameBoy LCD schematic
  • GameBoy Power & Cartridge schematic
  • GameBoy ROM+RAM+MBC1 Cart Schematic
  • GameBoy MBC1 circuit equivalent
  • Super GameBoy schematic
  • Quiz show indicator
  • Dreamcast interface
  • Flashing heart
  • Phoenix programmer
  • Funcard programmer
  • Bingo!!! (on your tv)
  • Slot car TV cronograph
  • Furby reverse-engineered circuit
  • Sanyo 20EZ monitor Arcade Game (300k ZIP)
  • Burger Time Arcade Game (500k ZIP)
  • Dig Dug Arcade Game (800k ZIP)
  • Frogger Arcade Game (500k ZIP)
  • Galaga Arcade Game (542k ZIP)
  • Gyrus Arcade Game (800k ZIP)
  • Junior Pacman Arcade Game (400k)
  • Ladybug Arcade Game (335k ZIP)
  • Mappy Arcade Game (470k ZIP)
  • Moon Cresta Arcade Game (300k ZIP)
  • Mr.Do Arcade Game (554k ZIP)
  • PacLand Arcade Game (316k ZIP)
  • Pengo Arcade Game (313k ZIP)
  • Q*Bert Arcade Game (600k ZIP)
  • Qix Arcade Game (476k ZIP)
  • Scramble Arcade Game (600k ZIP)
  • Time Pilot'84 Arcade Game (870k ZIP)
  • Xevious Arcade Game (450k ZIP)
  • Magic Wand Conjuring Trick
  • Quiz game circuit
  • E.S.P. Conjuring Trick
  • DIT shutterglasses controller
  • Tic-tac-toe game using PIC16F628
  • Archery timer
  • PIC micro Tetris game
  • Magic lamp, IR remote control jammer and other fun circuits (PDF)
  • Lego Mindstorms Double Rotation Sensor

  • Source

    Tuesday, June 20, 2006

    Discover Circuits

    Discover Circuits, with its 23,000+ electronic circuits or electronic schematics cross-referenced into 500+ categories, is a vital resource for engineers, hobbyists, inventors & consultants. The site's collection of links will help you find quick solutions for electronic design problems. Bad links are removed and new circuits or schematics are added frequently.

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    Telephone Circuits

    Telephone Ring Generator Using Switching Supply

    The telephone ring generator shown below generates the needed high voltage from a simple switching mode power supply (SMPS) which employs a CMOS Schmitt Trigger square wave oscillator, 10 mH inductor, high voltage switching transistor (TIP47 or other high voltage, 1 amp transistor) and a driver ...

    Telephone Ring Generator Using Small Power Transformer

    This ring generator will ring a telephone once every 10 seconds. The interval between rings can be lengthened or shortened by varying the value of ...



    Telephone In-Use Indicator


    Telephone In-Use Relay Controller


    Circuit to close a relay when any phone extension is off-hook. Voltage at the gate of the MOSFET should be ...

    Telephone Audio Interface

    Audio from a telephone line can be obtained using a transformer and capacitor to isolate the line from external equipment. A non-polarized capacitor is placed in series with the transformer line connection to prevent DC current from flowing in the transformer winding which may prevent the line from returning to the on-hook state. The capacitor should have a voltage rating above the peak ring voltage of 90 volts plus the on-hook voltage of...

    Microsoft Rolls Out Robotics Dev Kit

    By Lance Ulanoff

    Robotics has captured the minds and imagination of those inside and outside the technology market, but as a market unto itself, robotics can barely get its act together. Microsoft today announced during Robo Trend Inc.'s RoboBusiness Conference...

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    New Blog

    Welcome to my new blog!

    This site will contain new circuits and microcontroller programs for hobby use. Please check out this site from time to time for new updates.

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