5
•
Experiment to obtain best signal. Transducer
output should be at least 100-200 mV.
•
Peripheral vasoconstriction, often due to a
cold subject or room, can cut the signal
greatly. Touch subject's fingers to your
cheek -- coldness indicates vasoconstriction.
•
Model 1010 finger pulse signal differs from
usual pressure pulse signal due to poor low-
frequency response of transducer piezo-
electric element. Use a charge amplifier
circuit (see below) to correct response and
obtain a good pressure pulse waveform.
10K
To Model 1010
1M
22M
To signal conditioner
+
-
U2
LF411
3
2
6
7
4
V+
V-
47 nF
.
.
6
To measure carotid pulse:
•
place Model 1010 on one of the carotid
arteries, just below hyoid bone, and hold
there with VELCRO® strap or elastic
webbing 2.5cm (1") wide or more.
•
Use minimum tension needed to obtain an
adequate signal; expect 40-60 mV.
To monitor swallowing:
•
place Model 1010 on throat near base to one
side of thyroid cartilage; secure with elastic.
•
Properly placed, Model 1010 should produce
several hundred millivolts during a swallow.
To monitor Korotkoff sounds:
•
place Model 1010 under blood pressure cuff,
directly over brachial artery.
•
Model 1010 should produce 50 mV or more
per pulse.
To monitor heart sounds:
•
secure Model 1010 to chest with elastic
webbing. You will obtain best results when
Model 1010 is in direct contact with skin.
•
Connect Model 1010 leads to audio amplifier
or chart recorder.
