The apparatus consists of a 6" long 1/8" ID copper pipe held in a vertical position. This pipe is mounted with an LED-Photo Cell pair that detects when small
stainless steel beads, that are inserted at its top, fall inside the pipe. The circuit signals the event to a computer through a standard PC parallel port.
There are 2 versions of the "Bead Timer":
- In the first version the bead detected signal is latched in hardware and must be reset by the software. We experienced misses with this version and assumed that WINDOWS might have been reseting the latch while interfering with the printer port.
- In the second version the bead detected signal triggers a 555 timer that lengthens the signal to a hardware adjustable width. The adjustment potentiometer is accessible through an opening in the side f the 25 pin DIN connector cover. Also, in this
version, the circuit gets its power from the port input lines rather than the outputs, hoping to avoid interference from the WINDOWS operating system.
The following files to be copied to your "Windows/System32" folder if your system requires them.
- Show Data - This menu option allows monitoring the test as it progresses. A window showing the test results is open. It
updates each time a bead is detected. The "Shorter than Allowed" / "Cheating" cases are shown on the display, but the "Count" and "IBI
average" are replaced with pound signs ("#"), the IBI is displayed to show the justification for the dismissal. When the
"Show Data" option is selected while the test is already in progress or after the test is completed, any "Shorter than Allowed" case that may
have occurred is not displayed.
- Save As - The data saved to disk file does not include the "Shorter than Allowed" cases.
- Total Bead Count - This options displays a text box in which the bead total count can be edited. If this text box is left visible when the program is exited, it will be visible the next time the program is started.
- Shortest Time Allowed - When the timing between beads is less than this specified duration in seconds, the subject under test is
suspected to be cheating by picking up more than one bead at a time. The software interrupts the process and sends the subject a message. This message can be edited in the "Defaults" file: "
BeadTimerDFTs.ini". The checking for "cheating" can be suppressed by editing the defaults file "Cheater Checking" option. Checking is enabled if the string starts with a
letter "t" or "T" (for True), anything else will prevent checking from taking place (See "Defaults Options" below).
- Sounds / Collection - This option opens a new window ("Sound Collection" window) that permits building up a collection (list) of sound wave files with the "WAV" extension. A good source of
sound wave files usually is the "WINDOWS/Media folder. The Paths of the wave files are saved in an initialization file different from the other "Defaults Options" below. This file is:
Sounds / Starting - These four options let the user select a wave file for each of the four events, from the list / collection built using the "Sounds / Collection" option. To disable a sound the user should use a silent sound file such
as : "No Sound.wav", selecting a non existing file will cause the system "Standard Beep" to sound.
- Sounds / Bead Detected
- Sounds / Cheating
- Sounds / Ending
- Show Pulse Width - If there is a need to adjust the 555 pulse width, it can be monitored by the software.
- Show Port Address - If there is a need to change the parallel port address. In the "BeadTimerLatched.exe version the port address combo is
accessible by extending the program window down.
- Help on the WEB - This Web page is accessed through the menu: "Help" option.
Sample Defaults File
("BeadTimerDFTs.ini" is a word processor editable plain text file).
Editing this file is the only way to change some of this software features:
Cheater Checking Enabled/Disabled:
To enable the checking type the word "True" after the equal sign in the defaults file line: "Cheater Checking=True"
To disable the checking type the word "False" after the equal sign in the defaults file line: "Cheater Checking=False"
The message sent to the suspected cheater can be edited at the line: "Cheater Message=Inserting several beads at a time is not permitted"
2006 December 1
Last update: 2008 October 23