The Goerz multimeter, model: Minitest FE5101 dates from 1969 and was manufactured by the company Goerz Elektro Ges.m.b.H from Vienna.
Introductory sentence from the operating instructions: “It is a multi-measuring instrument, which is particularly suitable for service work in the field of news and radio technology and electronics due to its small dimensions and low weight as a pocket instrument It allows the measurement of: equal and AC voltages, DC and AC, resistance, capacitance and frequency. “
The internal resistance is 20kOhm for DC and 4kOhm for AC. The achieved accuracy is 2.5%
As overload protection, the moving-coil meter is equipped with antiparallel-connected diodes.
In this model, the measuring ranges are not to be selected by a selector switch, but each individual measuring range is designed as a socket on the device. The sockets themselves are suitable for 2mm banana plugs. The power supply for the resistance measurement comes from a 3V dry cell battery (type 2R10 duplex battery).
For the measurement of the capacitance with this device an external voltage is necessary, because here no own alternating voltage generator is installed. This said external voltage is the 50 Hz mains voltage which is connected to the device via its own supply cable. So a capacity measurement up to 500nF can be achieved. Measurements greater than 0.5uF are no longer possible due to the low measuring frequency. Goerz supplied a polystyrene transport case for storage and transport.
From the years from 1964 comes the analogue multimeter Unigor 3n from Norma, respectively Goerz-Metrawatt. It was characterized by the large measuring range of 52 measuring ranges, all of which can be selected with just one selector switch. The measuring mode and polarity reversal is realized with a push-button switch. All measurements (except the 10A range) are possible on just one terminal pair.
The measuring mechanism is a “clamping band measuring unit” with a very good vibration resistance and low self-consumption.
The internal resistance for voltage measurements is a maximum of 4MOhm in the highest measuring range (see photo technical data). The voltage drop in current measurements is given as 12mV in the 120uA range and 120mV in the 30A range. The measuring accuracy is 1% for DC and 1.5% for AC measuring ranges.
Like the Unigor 6e, the 3n model is also equipped with various safety features.
The power supply of the multimeter takes over a 1.5V mono cell.
A good friend of the older generation of technicians is certainly the analog multimeter of the manufacturer Unigor. In this case, it is the model Unigor_6e from the 70s.
An excerpt from the preface of the operating manual:
The electronic instrument Unigor 6e combines the advantages of classical measuring technology with those of modern electronics.
It was specially developed for measurements in the field of electronics and for all those applications where practically no power is required. The high sensitivity is achieved by means of a battery-powered transistor amplifier.
The field effect transistor chopper for DC measurements and the multiple negative feedback guarantee high stability and negligible drift. The large measuring range and the high accuracy of 1% at AC and DC, allows universal use in the radio and television service in test field and laboratories.
The “6e” offers a total
54 DC and AC / voltage ranges
13 dB ranges
12 resistance and capacity ranges
2 temperature ranges
The electronic components of the meter are powered by four 1.5V batteries and take a current of about 2.5mA. The working range of the electronics is between 4V and 7V. The battery is switched on with the rotary switch (which also represents the R, C adjustment knob at the same time). To check the battery voltage, a check position is provided on the measuring range shutter.
The Unigor 6e also offers a variety of protective devices and is therefore protected against damage caused by incorrect handling and overload. (I can remember quite well from my school time that this is not always the case: D)
The Unigor 6e has an electromechanical circuit breaker function. Its relay responds to overloads with DC and AC and requires no auxiliary power. The protection therefore remains fully effective even when the battery switch or battery is switched off. The restarting in case of permanent overload is prevented by a special switching mechanism.
Furthermore, fuses provide protection at the higher current ranges to respond in the event of a short circuit or tripping of the circuit breaker.
Against overvoltages at the inputs are voltage arresters at the input terminals whose breakdown voltage is lower than that of the internal circuit.