Using a PC as an assay counter-timer...

Paul N Hengen pnh at
Tue Feb 11 11:57:08 EST 1997

Richard T. Timmer (timmer at wrote:

> Hello,
> Before reinventing the wheel, let me pose this scenario to the avid
> readers of this newsgroup...
> We do many assays for various kinetic studies that require sampling at
> known times very exactly (i.e. a sample is removed at some time "t")
> with many samples done in parrallel.  Currently we have a mechanical
> counter/timer connected to a foot pedal.  We remove a sample to the
> stop solution, hit the foot pedal, and the time is recorded (on a
> hardcopy printout) at which the foot pedal was hit.  This mechanical
> system is beginning to show its age, and is frankly, a one of a kind
> device (custom made - many, many moons ago...).  
> As a replacement for this system we thought that some type of foot
> pedal could be connected to the serial port of standard XT PC.  A push
> of foot pedal would cause the elapsed time to be recorded, without
> stopping the timer/ each time point, for each sample, the
> foot pedal would be hit and the elapsed time at that moment recorded
> to disk in some type of ASCII file.
> Is this possible?
> Anyone know of a source of foot pedals that can interface to a serial
> port?
> Has anyone written serial interface software to do this?  Where?
> Thanks much in advance for your help.
> Cheers,
> Richard Timmer

How about having a voice activated setup where you give the word and it does
the same thing? Or maybe have it trained to some frequency of a buzzer or bell
that you ring? I think this would be easy to do given all the new software
available for voice recognition.  I remember there was a device hooked into the
serial port of a PC for recording the activity of lab mice when they run on a
wheel during the night. It was published in BioTechniques by Bob Horton and I'm
pretty sure the plans are linked from his homepage, but I'm having trouble
getting to it at the moment.


* Paul N. Hengen, Ph.D.                           /--------------------------/*
* National Cancer Institute                       |Internet: pnh at |*
* Laboratory of Mathematical Biology              |   Phone: (301) 846-5581  |*
* Frederick Cancer Research and Development Center|     FAX: (301) 846-5598  |*
* Frederick, Maryland 21702-1201 USA              /--------------------------/*
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