HARVARD 50-9513 Operating And Maintenance Instructions Manual

Publication #
Revision 0
Date 12/28/94

84 October Hill Road
M

assachusetts 01746

Tel.: [phone]
Fax: [phone]
e

-mail: bioscience
@harvardapparatus.com

W

eb Site: harvardapparatus.com

Operating and Maintenance

Instructions

Harvard

Isolated Preamplifier

Catalog Number:

50-9513

Table of Contents

Subject Page(s)

Caution/Warning Statement ............................................ 2

Introduction ....................................................................... 2

Specifications ..................................................................... 3

Operating Procedure:

Recording with Electrodes .......................................... 4

Siting and Fixing the Electrodes ................................ 5 - 7

Use with the Harvard Modular

Universal Oscillograph ................................................. 8 - 9

Use with the Harvard

Student Oscillograph .................................................... 10 - 11

Problems .............................................................................. 12

Service Information .......................................................... 12 - 13

Customer Contact Addresses ........................................... 13

Diagrams:

Figure 1 – Isolated Preamplifier Controls ................. 3

Figure 2 – ENG Electrode Positions ............................ 5

Figure 3 – EMG Electrode Positions ........................... 5

Figure 4 – ECG Electrode Positions ........................... 6 - 7

Figur

e 5 –

Modular Universal Oscillograph
Controls

........................................................ 9

Figur

e 6 – Student Oscillograph Contr

ols

..................

11

Figur

e 7 – Back Panel of Pr

eamplifier

.......................

12

2

Important Notice

This unit is intended for use as a research or teaching tool
ONLY and is not authorized for use as a component in a life
support device or other clinical system. Therefore, neither
we nor our agents can be held responsible if this notice is dis­regarded.

WARNING

50-6808 Harvard Surface Electrodes

When using Coupland-Davis type electrodes or ANY type of needle
electrode, ALWAYS STERILIZE THE ELECTRODES BEFORE AND
AFTER USE ON EACH SUBJECT to reduce the chance of skin
infections or blood-carried diseases being transmitted.

Introduction

The Harvard Isolated Preamplifier has been designed for ECG
(EKG), EMG, and ENG (EOG) recording with subject isolation. The
front end of the preamplifier is a battery operated opto-isolator.
The remainder of the circuit obtains its power from the host unit.

There are two types of input: a 3-pin socket for ordinary differen­tial applications, and a “5-lead” input for ECG limb selection, cou­pled with a 7-position selector switch. There is a 3-position gain
selector and 3-position filter selector.

NOTE: When this Isolated Preamplifier is to be used with our
Universal range of Oscillographs or with either the 50-4027 or
50-4028 4-Channel Interface Adapter, the 50-5966 Isolator Interface
Unit is also required.

Specifications

Batteries 2 standard 9 V “transistor radio” type (PP3 or

IEC designation 6LR61)

Inputs 5 standard color coded ECG 2 mm pin type

sockets LA, RA, LL, RL, C. Also 3-pin socket
for general differential input applications

Lead Selector Standard 7-position ECG lead selector: I, II,

III, AVR, AVL, AVF, V

Filtering 3-position filter switch:

30 Hz 3 dB down
150 Hz 3 dB down
15 kHz 3 dB down

Gain Selectable x10, x100, x1000

Other Facilities DC level control; battery level indicator;

choice of DC or AC coupling

Rear Panel Coupling lead for use with Harvard instru-

ments; battery housings

3

Figure 1

I s o l a t e d P r e a m p l i f i e r

INPUT

R.A. L.A. R.L. L.L. V

RED YELLOW BLACK GREEN WHITE

I

II

III

AVR

AVL

AVF

V

D.C. LEVEL

FREQ

CUT

GAIN

15 xHz

150 Hz

30 Hz

A. C.

D.C.

x 1000

x 100

x 10

HARVARD

(4)(3)(2)(1)

(6)

(5)

4

Operating Procedure

Please note the “Important Notice” on page 2

The instructions that follow are for use with the Modular Universal
Oscillograph and the Student Oscillograph. To use the Isolated
Preamplifier with the Harvard Electrophysiological Teaching Unit,
please refer to the instruction manual supplied with that unit.

Points About Recording with Electrodes

Human Subjects: First, always clean the area of electrode applica-

tion with surgical spirit or similar, to remove grease, dirt, grime etc..
When using Coupland-Davis type electrodes or ANY type of needle
electrode ALWAYS STERILIZE THE ELECTRODES BEFORE AND

AFTER USE ON EACH SUBJECT

to reduce the chance of skin

infections or blood-carried diseases being transmitted.

Always ensure that the electrodes are clean. This reduces noise on
your chart recordings.

Choose the siting of the electrodes carefully. Avoid areas of excess
fat (fat will reduce the amplitude of your signals).

Animal Subjects: If you are using needle electrodes, there is a
chance that a small DC voltage will develop at the electrode site
which may well “swamp” the input of the amplifier, causing the sig­nal to get progressively smaller until it finally disappears. This can
be countered by connecting the 50-8390 Harvard Capacitor Box
between the electrodes and the Isolated Preamplifier.