https://www.photonicsguy.ca/ 2026-04-06T20:39:24+00:00 https://www.photonicsguy.ca/ https://www.photonicsguy.ca/_media/wiki/dokuwiki.svg text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/electronics/tirepressuresensor/code?rev=1415904614&do=diff Tire Pressure Sensor Code Return to Tire Pressure Sensor Project. ;############################################################################### ;# TITLE "Pressure Sense" ;# ;# Program : Pressure sensor using an MPX5700DP sensor and LCD display ;# Version :1.0 ;# Revision Date : ;# Author : Jeff Brown ;# ;# ;# ;############################################################################### ; radix hex #define RA0_… text/html 2024-02-12T12:09:09+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/wiki/syntax?rev=1707739749&do=diff Formatting Syntax DokuWiki supports some simple markup language, which tries to make the datafiles to be as readable as possible. This page contains all possible syntax you may use when editing the pages. Simply have a look at the source of this page by pressing text/html 2021-07-06T14:15:59+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/t530?rev=1625580959&do=diff Lenovo T530 Laptop WiFi upgrade I successfully installed an Intel Dual Band Wireless-AC 7260 wireless card by modifying the whitelist in the BIOS. I've compiled this step-by-step guide with references as I had trouble finding a similar resource online. Living in Toronto, the 2.4GHz WiFi band is over saturated and my best wireless throughput was roughly 16Mbps, now with 5GHz Wireless AC, I get an average of 700Mbps. I decided not to upgrade to the latest BIOS and to attempt the whitelist modifi… text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/htaguide?rev=1415904614&do=diff My quick guide to the Ontario HTA for Bicyclists and Drivers Ontario Highway Traffic Act “highway” includes a common and public highway, street, avenue, parkway, driveway, square, place, bridge, viaduct or trestle, any part of which is intended for or used by the general public for the passage of vehicles and includes the area between the lateral property lines thereof; text/html 2024-02-12T12:09:09+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/wiki/dokuwiki?rev=1707739749&do=diff DokuWiki wiki:dokuwiki DokuWiki is a simple to use and highly versatile Open Source wiki software that doesn't require a database. It is loved by users for its clean and readable Formatting Syntax. The ease of maintenance, backup and integration makes it an administrator's favorite. Built in text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/electronics/voip/dvg-1120?rev=1415904614&do=diff DVG-1120 9600 Baud, 8N1 Serial Port Pinout RJ9ColourFunctionPin1BlkGround2RedRX (Data to Computer)3Grn4Yel?ColourFunction-BlkRedTX (from computer)GrnRX (To Computer)YelGround Commands CommandFunctionspy 16 *Show Debug info for SIPnwdbg bridge off text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/reference/flukemeter?rev=1415904614&do=diff Fluke 189/187/89-IV/87-IV Remote Interface Specification Archive of http://www.cfa.harvard.edu/~thunter/manuals/RemoteSpec89_18X.htm Retrieved October 2009 from Internet Archive, dated September 13th, 2006. Technical Note Fluke is providing this information to those few customers who would like this information. We give this information with the understanding that Fluke will not provide any additional support on this information. This means that our Product Support Service will not be able t… text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/dvr?rev=1415904614&do=diff MythTV DVR System Upgrade Hardware * Intel Celeron Dual Core E1200 CPU Allendale * Intel Desktop Board DG35EC * Product Guide * Integrated graphics with DVI out - Not used * Four Sata connectors * Gigabit Ethernet * 2x1024MB PC5400 RAM * Masscool Socket 775 CPU Cooling Fan * Cooler Master computer case * Nvidia 7300GT PCIexpress video card text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/rideau?rev=1415904614&do=diff Rideau Canal Kingston to Frontenac Provincial park. I thought downstream paddling would be preferred, but the information I found says we should paddle from Kingston up due to the prevailing winds. Guide I think Frontenac would be best, at the very least, they have the most detailed information on their website and they have Kevlar canoes. We pickup the canoes in Frontenac and drive them down to Kingston. Similar to Saugeen, we drive a car back to Frontenac, or leave a car there if we can get… text/html 2016-03-09T00:46:23+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/electronics/sumppump?rev=1457484383&do=diff Sump pump Monitor My parents have a cistern and a sump pump which would be useful to have some sort of water level monitoring. In the past, we would check the cistern level with a pressure gauge calibrated in inches of water. There was a rubber squeeze bulb which which would pressurize a plastic line which fed into the cistern, and the resulting level would be shown on the gauge. text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/gps?rev=1415904614&do=diff GPS Kayaking * Oshawa Kayaking * Kayaking on the Rideau Canal Bicycling * Niagara Falls to Niagara on the Lake * Welland to Port Colborne Automatically generated list ~~PAGEINDEX=:gps~~ (Automatically generated list) Bicycling Links * Greater Niagara Circle Route GIS * LIO Internet Map Browser System * Niagara Maps gps logging track google maps route text/html 2017-11-12T18:39:20+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/archive/coop?rev=1510511960&do=diff Coop * $150 USB-GPIB Adapter * PIC USB-GPIB Project * <http://www.thegleam.com/ke5fx/gpib/readme.htm> * <http://www.thegleam.com/ke5fx/gpib/7470.htm> * <http://www.printcapture.com/details.html> * <http://www.webalice.it/hotwater/PicPlot.htm> * <http://www.synrad.com/e-newsletters/08_09_07.htm> * <http://www.optikon.ca/photonic.htm> URL's * <http://www.repairfaq.org/sam/laserco2.htm#co2sdf> * <http://www.protectivepackaging.ca/310.htm> TEA CO2 <http://www.vin.bg.ac.yu/V… text/html 2017-11-12T18:38:16+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/archive/eeepc?rev=1510511896&do=diff Eee PC Customizations Some Eee PC customizations via shell script * Disable suspend to ram when AC adapter is plugged in and the lid is closed. * 30 minute timeout, after which the computer is suspended anyways * If the lid is closed and the AC adapter is unplugged, then suspend to ram is run. text/html 2017-11-12T18:33:58+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/archive/nslu2?rev=1510511638&do=diff Embedded Linux computer with 1-wire net Linksys NSLU2 running Debian Linux off of flash memory, polls a 1-wire net every 5 minutes and records the data (temperature and humidity) to a remote SQL server. 1-Wire PIC18 Microcontroller PIC18F4523 reading an ADT7410 temperature sensor via I2C. text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/electronics/mbed?rev=1415904614&do=diff MBED Ethernet Magjack - [lU1S516LF Datasheet] [Pinout] PinmbedP1RD+P2RD-P3VccP4n/cP5n/cP6VccP7TD+P8TD- <HTML><BR CLEAR=ALL><BR></HTML> First Project - Halloween Window Setup Light Sensor Possible IC to use: IVC102 text/html 2023-12-20T15:30:29+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/esphome/watermeter?rev=1703086229&do=diff Water meter monitoring Hardware Using a ESP32 with QMC5883L compass module. TBD Accuracy Quite accurate, each interval (max to min to max) from the water meter appears to be 32.5ml, this was confirmed over the course of a few days and about 1.6 m³ of water (about 49 thousand intervals). text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/405nmlaser?rev=1415904614&do=diff 405nm Laser Diode Blue, Violet, almost Ultraviolet really. I made a driver board and just need to finish the heatsink and mount it in a case. I bought a translucent blue project box from Hammond that I'll be mounting the laser in. * 405nm (Blue) Laser text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/interferometer?rev=1415904614&do=diff Michelson interferometer I want to create a small Michelson interferometer using a laser diode and small, inexpensive mirrors. <http://www.iop.org/EJ/abstract/0143-0807/25/6/012> text/html 2024-02-12T12:09:09+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/wiki/welcome?rev=1707739749&do=diff Welcome to your new DokuWiki Congratulations, your wiki is now up and running. Here are a few more tips to get you started. Enjoy your work with DokuWiki, -- the developers Create your first pages Your wiki needs to have a start page. As long as it doesn't exist, this link will be red: text/html 2016-03-09T02:48:00+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/electronics/mysensors?rev=1457491680&do=diff MySensor board After reading about the MySensors project, I decided to design a small circuit board to hold the Arduino and radio module. Status: * Nov 25th: I've assembled two working boards. Imgur photos * Nov 24th: I received the boards, Yay!! * Nov 7th, 2014: I'm waiting on the PCB's from text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/electronics/panelmeter?rev=1415904614&do=diff Panel Meter Interface Components * Panel Meter * [MCP41050] * [LM321] * [MAX5487 Digital Pot] * [12-bit DAC with SPI Interface] 1mA Full scale meter 94 Ohms coil resistance 5K Ohm resistor @ 5V = 1mA MCP4821 Pin No.SymbolFunction1VddSupply (2.7 to 5.5V)2CSChip Select3SCKSerial Clock Input4SDISerial Data Input text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/electronics/tirepressuresensor?rev=1415904614&do=diff Tire Pressure Sensor The pressure is determined by the formula, <m>P=0.145* Parts Part# Description Source Cost MPX5700DP-ND0-101.5PSI Pressure sensorDigikey$16 2 Ft 1/4ID hoseHome Hardware$1.50 2 crimp style hose clampsHome Hardware$1.60 text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/electronics/x10?rev=1415904614&do=diff X10 Interfacing X10 Mini Timer power supply The LCD display seems to die after a few years (on three units I've used) so I figured out the pinout. 4N35's are used internally for opto-isolation, The power is from a transformer internally, with a rectifier and a capacitor. text/html 2016-03-09T03:23:15+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/3d/openscad/start?rev=1457493795&do=diff OpenSCAD Endcap Endcap for a clear plexiglass tube to hold an LCD display module <HTML><BR CLEAR=“ALL” /></HTML> Drive Pulley Pulley for a drive belt for a Kodak Slide projector <HTML><BR CLEAR=“ALL” /></HTML> text/html 2021-07-06T13:33:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/eagle?rev=1625578394&do=diff CadSoft EAGLE Libraries <https://github.com/Photonicsguy/Eagle> eBay parts Footprints for components I've bought from eBay * eBay search for Arduino pro mini * eBay search for nrf24l01+ module Arduini mini pro NRF24L01+ module I've included a keepout block to prevent ground planes or traces from being routed under the antenna. I'm using this module for text/html 2014-11-13T20:01:05+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/education?rev=1415908865&do=diff Education I have a Bachelor's of Applied Technology - Photonics degree from Niagara College. I have also previously graduated from the Computer engineering technician program also at Niagara College. Bachelor of applied Technology Photonics In addition to lasers, I've had the opportunity to be exposed to all kinds of neat and interesting stuff text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/electronics?rev=1415904614&do=diff Electronics Pages This section is more for quick notes. See Electronics Projects for more pages ~~PAGEINDEX=:electronics~~ (Automatically generated list) text/html 2017-01-09T21:38:15+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects?rev=1483997895&do=diff Projects THIS PAGE IS NOT ORGANIZED Electronics * 7-segment display Pressure Sensing * Tire pressure sensor * Sump pump level Temperature * Thermocouple GPS * Track Logging Other ---------- ~~PAGEINDEX=:projects:electronics~~ ---------- Physics experiments I'd like to try Mercury and Aluminum text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/taurus?rev=1415904614&do=diff Vehicle If I only had a single wrench, I hope it's 13mm. 10mm for thermostat bracket bolts. Remote Starter Does not engage A/C, rear defroster. Horn is not connected either (for programming). Rear Defroster relay [Relay] ContactNote85Coil - Switched by ECM, ground to activate text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/test?rev=1415904614&do=diff E-mail: <HTML><a href=“<http://www.google.com/recaptcha/mailhide/d?k=01tVyRJQeRv0b0Ha_nc2-JrA==&amp;c=OjytmEaPBjEYw66AkzhXoDVJUL9FEpgdlKKLq0uwCcg=>” onclick=“window.open('<http://www.google.com/recaptcha/mailhide/d?k>\07501tVyRJQeRv0b0Ha_nc2-JrA\75\75\46c\75OjytmEaPBjEYw66AkzhXoDVJUL9FEpgdlKKLq0uwCcg\075', '', 'toolbar=0,scrollbars=0,location=0,statusbar=0,menubar=0,resizable=0,width=500,height=300'); return false; text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/todo?rev=1415904614&do=diff <http://www.otherpower.com/otherpower_experiments.html> <http://link.aip.org/link/?JAPIAU/48/3895/1> <http://www.dacomwest.de/e_index.htm> TODO * E-mail Jim Bixby * Locate Rich Heineck <http://home.carolina.rr.com/gcodemcode/ttftodxf.htm> Plugins Notes Other * <http://www.matwei.de/> text/html 2021-01-19T17:23:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/archive/cetus?rev=1611077023&do=diff Cetus Tracklog Cetus TrackLog (Linux) 1.35 Copyright (c) 2001-2004 Cetus http://www.CetusGPS.dk Usage: TrackLog [options] trackfile... <Enter> Options (* are default values): -fu user defined format * -dt TAB delimited * -fx GPs eXchange format (GPX) -ds semicolon delimited -fi Gliding Commission format (IGC) -dc comma delimited -fr NMEA RMC sentence format -dl linefeed delimited -pd decimal degrees * -sp period as decimal … text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/arduino/lcd?rev=1415904614&do=diff LCD Display MJKDZ I2C board from eBay. Notes: * eBay search for board * * I2C address is actually 0x20, not 0x27 * I'm using the New LiquidCrystal library * Need pull-up resistors on SDA and SCL lines (A4 & A5 pins) Test Code #include <Wire.h> #include <LiquidCrystal_I2C.h> #define lcdAddr 0x20 // set the address of the I2C device the LCD is connected to // create an lcd instance with correct constructor for how the lcd is wired to the I2C chip LiquidCrystal_I2C lcd(lcdAddr, 4, … text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/electronics/battery?rev=1415904614&do=diff Tenergy Li-ion 18650 Pack Manufacturer site Capacity6600mAhVoltage3.7VDimensions69mm Length x 54mm Width x 18mm ThciknessWeight9.0 ozMax. charge current1AMax. discharge current3.5ACut off voltage/Over-Charge Protection: 4.35VOver-Discharge Protection:2.4V * High quality 3.7 V Li-Ion rechargeable battery pack text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/gps/algonquin?rev=1415904614&do=diff Achray, Algonquin camping trip View my Algonquin pictures. <html> <iframe src=“<http://photonicsguy.ca/gpsmaps/algonquin.htm>” width=“800” height=“800” marginwidth=“0” marginheight=“0” scrolling=“no” frameborder=“0”> <a href="http://photonicsguy.ca/gpsmaps/algonquin.htm">Click here for the map</a> text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/gps/nftonotl?rev=1415904614&do=diff Niagara Falls to Niagara on the Lake <html> <iframe src=“<http://photonicsguy.ca/gpsmaps/080622bikeride.htm>” width=“800” height=“800” marginwidth=“0” marginheight=“0” scrolling=“no” frameborder=“0”> <a href="http://photonicsguy.ca/gpsmaps/080622bikeride.htm">Click here for the map</a> text/html 2014-11-13T21:23:50+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/electronics?rev=1415913830&do=diff My Electronic Projects ~~PAGEINDEX=:projects:electronics~~ (Automatically generated list) Suppliers Online * Digikey - Supplier of choice * Sparkfun - Great hobby site, Interesting components, I've ordered quite a few parts from them. * BatchPCB.com - Great hobby site for fabricating PCB's text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/logger?rev=1415904614&do=diff Data Logging Software Perl program is on it's way, writing it now. LiveGraph - Excellent graphing software written in Java, I use it as a frontend. Perl Script Install sudo cpan -i Device::SerialPort sudo cpan -i DBI sudo cpan -i LWP::Simple sudo cpan -i Time::HiRes text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/ulaser?rev=1415904614&do=diff U doped Laser Excited-State Absorption in Fluorescent Uranium, Erbium, and Copper-Tin Glasses PREPARATION AND PROPERTIES OF POTENTIAL GREEN LASER MATERIALS CONTAINING EXAVALENT URANIUM Fluorescence Spectra of Uranyl Ion in Various Environments Heavy-element chemistry at Los Alamos Factors affecting the threshold for laser action in CaF2 crystals doped with uranium and other host lattices - No access Uranium-doped calcium fluoride as a laser material - No access Q-Switching Spectral Bleac… text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/vintage/next?rev=1415904614&do=diff NeXt Cube From <http://www.bangmoney.org/nextstep/root_password.html> Lost Root Password If you've forgotten the root password, you'll need to follow the following procedure to reset it so you can login as root. This is most helpful to people who've just purchased a used NeXT but don't know what the root password is. Reboot the system. Immdeiately after the "Testing System" message is replaced with "Loading from disk", hold down the right command key and press the tilde (~) on the numeric k… text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/gps/bicycling/june22?rev=1415904614&do=diff Niagara Falls to Niagara on the Lake <html> <iframe src=“<http://photonicsguy.ca/gps/080622bikeride.htm>” width=“800” height=“800” marginwidth=“0” marginheight=“0” scrolling=“no” frameborder=“0”> <a href="http://photonicsguy.ca/gps/080622bikeride.htm">Click here for the map</a> text/html 2014-11-13T22:37:16+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/electronics/7segdisplay?rev=1415918236&do=diff 7-segment display module [Working Display] Arduino library available on Github This was one of my first doublesided and surfacemount boards. I made this board using Eagle for layout and then I used BatchPCB to manufacture the board. The board operates correctly, however, if I were to revise it, I would use a larger SMT resistor than the 0402 size. The board will be controlled via I2C from a PIC microcontroller, initially for the pressure sensor and later for other projects. text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/electronics/cardreader?rev=1415904614&do=diff Magtek Card reader MAGTEK 21045002 MagStripe card reader. [Datasheet] Single Track, only reads Track 2 2.7 to 5.5VDC When no card is present all pins are high. When a card is present pin 5 goes low and remains that way for 140ms after the entire card has been read. text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/electronics/dgpsbeaconrx?rev=1415904614&do=diff DGPS-11 Beacon Receiver Si-tex DGPS-11 Beacon Receiver module mounted in a weatherproof housing. Wire Function Red+3A fused 10.8 to 31.2VDC OrangeRS-232C In WhiteRS-232C Out Black- Negative BlueTTL Out GreenData Ground BrownShield GroundHow can I tell if my WAAS GPS is giving me a corrected fix? Look for a "D" in your Latitude/Longitude readout. text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/electronics/relayboard?rev=1415904614&do=diff Relay board SPDT JW1FEN relays from an old UPS. Matches closest to Digikey Part# 255-1114-ND [JW Relay datasheet] [Schematic] [Board layout] <HTML><BR CLEAR=“ALL”></HTML> OptoRelay Board G4PB16 - G4 16-channel I/O Module Rack * G4 ODC5 - G4 DC Output 5-60 VDC, 5 VDC Logic * G4 OAC5 - G4 AC Output 12-140 VAC, 5 VDC Logic text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/projects/electronics/sdgpslogger?rev=1415904614&do=diff SD GPS Track Logger Why? This is why:Bicycling Trips ICSP Connector Need a PIC18 chip with more memory, I'm using the PIC18F4685 with 96Kbytes of program memory. Microchip Mass Storage Class Firmware [Still not working] Still not working. Might be software or hardware, I'll need to check it on a digital oscilloscope. Correct clock rate (less than 400KHz). text/html 2014-11-13T18:50:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.photonicsguy.ca/school/research/start?rev=1415904614&do=diff Unflatten pixmap iVision iMAQ Vision NI-IMAQ for USB Cameras * Fluorogen * * Crookes Radiometer * Quantitative use of a Crookes radiometer * A Modified Theory of the Crookes Radiometer * The radiometer revisited