An inexpensive 28-V timer circuit using solid state and relay devices

An easily constructed 28-V dc timer circuit is described. The circuit is as precise, reliable, and versatile as some commercially available units, but is much less expensive to construct.     

An improved circuit for control of LED luminance

The light-emitting diode (LED) is becoming increasingly popular as a luminance source in behavioral research. We describe a simple, inexpensive LED driver circuit that produces luminances almost linearly proportional to an input voltage. Negative feedback provides a stable output. Unlike previous designs, the LED is ground referenced.     

Integrated circuit random foreperiod device and digital interval timer1

A digital integrated circuit computer that produces random (as opposed to pseudorandom) foreperiods is described. Also contained in the device is a precision digital interval timer.     

An accurate millisecond timer for the Commodore 64 or 128

The use of the Commodore 64 or 128 as an accurate millisecond timer is discussed. BASIC and machine language programs are provided that allow the keyboard to be used as the response manipulandum. Modifications of the programs for use with a joystick or external switches are also discussed. The precision, flexibility, and low cost of these machines recommends their use as laboratory instruments.     

An automated open-field apparatus utilizing an improved resistance detection circuit

An open-field apparatus that can be automatically operated is described. Detection of movement is electronic and based upon the fact that the S will complete a circuit path when crossing an open field. The circuit is very sensitive yet quite immune to the usual problem of 60-Hz interference.     

An inexpensive digital millisecond timer and event counter

A simple circuit for a digital millisecond timer and event counter is described. The total cost of the unit including all components, a power supply, and an enclosure is less than $30. Daily use in simple reaction time experiments has demonstrated the reliability of the design.     

An external millisecond timer for the Apple Macintosh with applications to cross-modal lexical priming

The circuit and program described in this report allow researchers to use Macintosh personal computers to conduct research that requires timing with millisecond accuracy. This is accomplished with external response keys and an external clock that sends characters through the Macintosh’s serial port. For researchers interested in cross-modal lexical priming tasks, a tachistoscopic slide shutter is incorporated to allow for accurately timed presentation of visual stimuli. Because the visual display and response keys are external to the computer, display and reaction times are not subject to the timing constraints inherent to the keyboard or the Macintosh Event Manager. All circuit diagrams and code are in the public domain.     

An improved method for tetrachoricr

From the ratio of the cross-products of a fourfold table, with the application of two tabled corrections, tetrachoricr's can be estimated with a mean discrepancy of less than .005 even when splits vary greatly from the medians. The necessary calculations can be handled by slide rule and the correction tables used without interpolation.     

A delay timer for presenting auditory and visual probes

A circuit designed to present auditory or visual probes is described. The circuit allows the probes to be delayed by a specified amount of time, and the volume (for auditory probes) or intensity (for visual probes) may also be adjusted. The circuit may be triggered by any device capable of emitting an electronic pulse-such as a computer or a tachistoscope.     

An improved shocking surface for pigeons and rats

A resistive shocking surface and an appropriate power supply are described. The efficacy of the system is illustrated with some data on the activity of pigeons and rats as a function of the voltage applied.     

A precision electronic timer for the measurement of acoustic signals

An electronic speech timer that uses only relatively inexpensive and readily available electronic components and common circuitry is described. This device rapidly and accurately measures the durational characteristics of speech and the durations of other acoustic signals over extended lengths of time. Its application to the measurement of total speaking time, articulation time, and phonation time are outlined. Accuracy, reliability, and validity are discussed and compared with other, more time-consuming and cumbersome methods of durational measurement.     

Millisecond interval timer and auditory reaction time programs for the IBM PC

Many types of behavioral research require the determination of elapsed time, for example to establish interstimulus intervals and to measure reaction time. The use of an IBM PC for on-line control of such applications is limited by the poor timing resolution ordinarily available. The IBM BIOS time information that is used for the BASIC TIMER function can result in interval timing errors as great as 110 msec. A machine language subroutine is described that can provide 1-msec accuracy. A BASIC program is also described that employs this subroutine to measure auditory reaction time.     

An inexpensive sound-activated switch for experiments measuring vocal-response times

An inexpensive sound-activated switch suitable for experiments measuring vocal-response times is described. This switch is comparable to many commercially produced switches in terms of its control over input sensitivity and response delay times, but it can be assembled for a fraction of the cost. Additionally, the present switch provides many features not found on standard commercial models such as a built-in speaker for monitoring the input signal and output jacks to facilitate simultaneous recording of this signal. Reliability estimates suggest that performance for this switch is comparable to that of a Scientific Prototype Model 761-G when both units are equated for frequency sensitivity and response delay time. In all, this switch offers a reliable and practical alternative to commercially produced devices for experiments in which the onset of an auditory signal must be accurately detected.     

An improved video multiplexer for behavioral research

Wellens and Revert (1979) described a solid-state circuit that allowed two sources of video information to be multiplexed and recorded using one videotape machine. On playback, the demultiplexed video signal allowed the original video channels to be viewed independently on separate television monitors. Recent changes in videocassette recorder technology have improved the playback quality of recorded images but disrupt the demultiplexing process when freeze frame or search options are selected. Improved multiplexing techniques that overcome these limitations are described.