Shure 66D User Guide

DATA SHEET No. 162

DATE: September 1940

SUBJECT: Model 66D Piezoelectric

Stethophone

MODEL 66D PIEZOELECTRIC STETHOPHONE

GENERAL:	Model	66D	Stethophone is	primari-
	ly designed for pickup or heart-
	beats	and	chest sounds.	A pie-

zoelectric crystal converts the vibrations transmitted through the flesh into corresponding electrical impulses for amplified reproduction or recording. The instrument responds with uniform efficiency to the entire frequency range covered by heart sounds, murmurs, rales, etc. Model 66D replaces the earlier Model 65A Stethophone.

The new Stethophone is highly sensitive to the vibrations produced by body sounds but is extremely insensitive to air-borne or acoustic sounds. It is therefore possible to use the instrument in close proximity to loud speakers without acoustic feed back, and to successfully amplify extremely faint body sounds in the presence of external noises. This has not been possible heretofore with electrical Stethoscope devices which acoustically pickup body sounds from an air chamber.

In operation the Stethophone is simply applied to the body with moderate pressure in much the same way as the conventional Stethoscope would be used. A suitable high gain amplifier and reproducing or recording equipment must be supplied by the purchaser.

APPLICATIONS : The usefulness	of the Stethophone
in conjunction with the proper
amplifying and	reproducing equip-

ment has extended to fields which are far beyond the possibilities of the ordinary Stethoscope. Heart and chest sounds can be observed with much greater clearness than with a Stethoscope. Extremely faint noises can be heard clearly with the Stethophone which would be difficult or impossible to detect with the ordinary Stethoscope.

Auscultation

A 66D Stethophone, in conjunction with a suitable amplifier with one or more sets of headphones, constitutes the simplest complete equipment for auscultation. The sounds can be heard by several persons simultaneously by simply providing a sufficient number of headphones. This feature is particularly useful in teaching auscultation to medical students.

Clinical Demonstrations

By feeding the output of the amplifier to one or more suitable loud speakers, body sounds can be demonstrated to a large group without the necessity for individual headphones. If desired, the demonstration can be made at a point remote from the patient.

Surgery

The Stethophone Can be strapped to the chest of a surgical patient during an operation and the condition of the patient’s heart can be observed continuously throughout the course of the operation. The observation may be made at a distance from the patient by suitably extending the connecting cord thus causing a minimum of interference with those actually engaged in the surgery.

Visual Observation

By means of a cathode ray oscillograph or other suitable device, the electrical wave forms which correspond to the body sounds may be observed visually. In this way it may be possible to observe abnormalities which might not be apparent from auscultation.

Graphic Records

By means of a suitable recorder, recording galvanometer, or oscillograph, permanent records of heart sounds can be made which are analogous to the Well known electrocardiograph records.

Sound Recording

With the aid of the Stethophone, recordings can be made or heart end body sounds by any of the well known sound recording methods. "Instantaneous" phonograph discs are especially Convenient for this purpose. Such sound records offer convenient means for demonstrating abnormal heart sounds to students.

Many other applications of the Stethophone will undoubtedly occur to those in the medical profession.

CONNECTIONS: Suggested block diagrams of the 66P Stethophone, associated amplifier and various reproducing,

indicating and recording devices are shown in Fig. A. Many other arrangements are of course possible.

The Stethophone should be connected to the grid circuit of the first tube across a resistance of 5 megohms, as shown in Fig. B.

The output level Of the Stethophone depends upon individual conditions but good results should be obtained with high-gain amplifiers designed for crystal microphone operation.

A 7-foot cable is supplied attached to the Model 66D. If necessary, added cable may be attached for extension purposes to a maximum of 25 feet total length. High quality, low-capacity cable should be used. It is essential that the leakage resistance of the cable be high so that it will not appreciably reduce the effective shunt resistance across the Stethophone. Heartbeat sounds are of relatively low frequency and leakage resistance will reduce the low frequency response.

When splicing in extra lengths of cable, the respective coded conductors should be sol-

COPYRIQHT 1940 SHURE BROTHERS. CHICAGO

( O V E R )

PRINTED IN U. S. A.

No. 162

DATA SHEET

dered together and carefully insulated with a good

125° F. or permanent damage to the crystal may

grade of rubber

tape.

A wrap or fine wire or a

result.

piece of

metal

braid

sleeving

soldered to

the

FREQUENCY

Heart

and chest sounds

are

made

shield of

the

cables

should be

used

to

cover

the

RESPONSE:

up of

frequecies

below

approxi-

joint of

the

cable

to

complete the shielding.

mately

1,500 cycles and

the

66D

Connector

fittings

are

suitable

for

jointing

Stethophone has

been

designed to

reproduce these

cables if

they

provide

complete

metallic shield-

sounds faithfully and accurately.

The

response

ing or the conductor.

to frequencies above 1,500 cycles is low, thus

lessening pickup of undesirable high-frequency

sounds. The response is down 10 db at 2000

OPERATION:

Although the crystal unit Of the

cycles and down 25 db at 8000 cycles.

By

suit-

Stethophone is not extremely del-

able design of the amplifier, the transmitted

icate, It should not be allowed

frequency range may be adjusted to accentuate

to come in contact with hard, sharp objects. It

either normal heart sounds, or murmurs, in any

should not be

operated

at

temperatures

exceeding

desired manner.

SPECIFICATIONS

Voltage Sensitivity: The output level depends upon individual conditions. The output voltage for an average heartbeat Is of the order of 5 to 10 millivolts r.m.s.

Recommended Load
Impedance:	5		megohms
	MODEL,		66D
	(See Fig. C)
Diameter. . . . . . . .			1-5/16"
Thickness . . . . . . .			15/16"
Finish. . . . . . . . .			Chrome	Plated
Net Weight (less cord).			3	oz.
Shipping Weight . . . .			3/4	lbs.
Code Word . . . . . . .			RUTEF
List Price. . . . . . .			$35.00

Guarantee: Every Shure Stethophone is guaranteed to be free from electrical end mechanical defects for a period of

one year from date of shipment from the factory, provided all instructions are complied with fully.

License	Shure Crystal	Devices are	licensed		FIG. A
Notice:	under patents of the Brush Develop-
	ment Company.	Shure patents	pending.

F O R M N O . 1 6 2 1 2 4 3 ¼ C