Used in Physics and Electrical Engineering laboratory experimentsPotentiometer, Type D-73-E in polished wood box with lift out circuit diagram inside the lid. Black top panel with terminal posts, switches and selector knobs.Black Dymon tape on lid "Ass.No. 50"scientific instrument, potentiometer, physics, electrical engineering, laboratory

Students potentiometer type D-73-A. Black top panel with terminal posts, elector knobs and switches. In a polished wood box wit lift-off lid. Circuit diagram inside lid. Serial Number 3008scientific instrument, potentiometer, physics, electrical engineering, laboratory

Potentiometer Volt Box, 6 ranges: 1.5, 15, 30, 150. Black terminal panel on top of polished wood box. Large circular ventilation holes in all six sides. Distributed by A.E. Supplies Pty Ltd., Melbourne. scientific instruments, potentiometer volt box, cambridge instrument co. ltd, volt box

This general purpose Multi-meter was manufactured after 1950 and used by the SEC Vic (Kiewa Hydro Electricity Scheme) from that date until late 1900's. It was used to measure very small voltages associated with the operation of the various Hydro Generators. The readings were able to be shown by the resistor in use in the current circuit. During this time period, high quality testing instruments were either sourced from Europe or England. This particular meter was manufactured in the Netherlands. This type of "old" analogue meter was replaced by digital meters whose electronic components are a fraction of the size of the older analogue ones.This analog General Purpose multi-meter is quite a large (for handheld mobile) apparatus which permits the easy monitoring of electrical variations within the large SEC Victoria Hydro Scheme's electrical generators. These generators are powered by the hydro force of "stored" water at a higher altitude. The establishment of both the NSW and Victorian Hydro schemes was achieved from the mid 1900's to the 1960's. At this point in time the need for additional power sources to quench both an industrial and domestic demand for electricity was purely an economic and not and environmental (carbon reduction) factor. This hydro scheme was instigated by "the Government of the day" as a bold move and was the major force of the World War II refugee and "technical" workforce inclusion of skilled and unskilled migration into the Australian environment. Although this mass "invasion" of workers with families was thought of in some circles as intrusive, the expansion of population post war years and its integration into the Australian rural sector, produced the multi- lingual multi-cultural diversity of later years.This General Purpose Multimeter is an analogue meter i.e. it has a needle arm that moves across a scale of divisions. This is a large(hand held) device due to the mechanical movement system within and the large size of its electronic components of its circuitry.There are two black bake-lite push buttons operating the wire inserts Positive/negative leads at the top. The meter (protected with a glass window) has clearly marked graduations (top - volts, bottom amperes). Below this are two bake-lite dials (left "potentiometer the right one measuring range selector). Below this is a "dial" switch to input the desired resistance measuring range "V" Front "H&B ELIMA" and to the right Elavi 15n. 0n the front side is a label "STATE ELECTRICITY COMMISSION OF VICTORIA TRANSMISSION DEPT E.C.No." On the bottom of the base is a stenciled layout of the battery "layout" including the fuse . The information notice is presented in five languages starting with German, English,French, Italian, Spanish and Dutchsec vic kiewa hydro scheme, alternate energy supplies, alpine population growth

The first all transistor hearing aids appeared in 1953. They were created to replace vacuum tubes; they were small, required less battery power and had less distortion and heat than their predecessor. The vacuum tubes were typically hot and fragile, so the transistor was the ideal replacement. The size of these transistors led to developments in miniature, carbon microphones. These microphones could be mounted on various items. There were body hearing aids where the earpiece was connected to the hearing aid and battery pack worn on the body. Ear level hearing aids consisted of eyeglass, behind the ear (BTE), in the ear (ITE), and in the canal (ITC, CIC) hearing aids. A new aid type, the Calaid V, was introduced featuring a forward facing microphone, and three potentiometers for adjustment of maximum gain, maximum power output, and low frequency roll off. The Calaid V was introduced in the early 1980s and remained the most frequently used aid in NAL's service for the next ten years (From: THE CALAID: AUSTRALIA'S OWN HEARING AID by Laurie Upfold and Ray Piesse Single Behind-the-ear hearing aid. Provided and manufactured by the NAL (National Acoustic Laboratories), part of the Commonwealth Department of Health. "CALAID/V" on bottom face