analogue multimeter – Goerz Minitest

Goerz Minitest
Goerz Minitest

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%

IMAG1503
inside view

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).

 

IMAG1497
scale

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.

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analogue multimeter – Unigor 3n

Unigor 3n
Unigor 3n

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.

 

Technische Daten
technical specification

 

 

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The steam engine

IMAG0062
Wilesco steamengine

The following piece is about 40 years old model steam engine from the manufacturer Wilesco. (Thanks to Manfred for the loan for the media preparation). The model consists of a highly polished and nickel-plated brass kettle, which is built into an old copper-colored boiler house with brick pattern. Heating is done with a dry spirit burner located under the boiler. The pressure vessel has a spring safety valve and a „Domdampfpfeife“. The pressure line is led to a single-acting pendulum cylinder, which in turn drives the crank and the flywheel on it via a connecting rod.Trockenspiritusbrenner.

IMAG0064The entire model is mounted on an iron plate. In order to be able to drive mechanical models with the machine, a pulley is mounted on the shaft of the flywheel. Since the model has been stored in a carton for the past forty years, a few small jobs have been done. Piston and crank were stiff and had to be cleaned and re-oiled. The crank was a bit out of alignment with the flywheel shaft.

IMAG0057The seals of the „Domdampfpfeife“ and the pressure relief valve were also brittle and hardened and were replaced. Here I was able to use a suitable punching tool made of „new“ old gasket material to knock out and insert two new gaskets. Now the model was a little bit freed from the dust of the last years and cleaned and a start attempt was nothing in the way.

Now the spirit burner could be filled with a small piece of dry spirit, which was probably even older than the machine itself. At least the original box looks like this:

IMAG0054 IMAG0055

 

Invalid Displayed Gallery

 

 

 

 

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science kits PHILIPS EE 2000 series

EE2050
EE2050

Another electronics kit from my youth is the Philips EE series. It dates approximately to the years 1976-1979. The box presented here is the EE2050. Unfortunately, this is no longer the original that I recorded back then, but a version bought on eBay. But this is a real collector’s item, because the box has never been recorded.

The boxes (EE2003 / 41/50/51/52) under my custody have unfortunately not survived the years. Since the modular system was designed in such a way that all components were „free“, ie not riveted to any sockets (just as they were also used in industry), I always used them. If I needed a resistor or capacitor quickly, the kit had to serve as a „donor“.

Befestigung des Bauteils auf der Grundplatte
Fixing the component on the base plate

The concept of the modular system: It consists of a perforated plastic base plate through which a hairpin spring is inserted. This hairpin spring in turn holds a spiral spring. Now, between the hairpin spring and the upper end of the coil spring, the connection wire of the component can be clamped.

IMG_3779
Transistor on printed circuit board

The components themselves are contained in the box as they are also commercially available. An exception here are only the transistors and transformers. They are mounted on a small printed circuit board, which facilitates assembly and also protects the component itself from mechanical stress.

In the final stage, the box consists of two bolted base plates, which in turn are bolted to a control panel. In this media console then turn capacitors, rotary potentiometers, buttons, bulbs and a speaker place. The number of experiments to build is also huge. The manuals are very well structured. They describe the basics of DC technology, as well as the operation of the circuits.

Here is an excerpt from the inscription of the electronics box. Note the gender-oriented spelling 🙂

 

Wonderful world of electronics – a mysterious world that every boy wants to get to know and understand. This electronic kit gives him the opportunity to easily gather his own insights in this field. The box contains a richly illustrated instruction book and over 150 items – e.g. 10 resistors, 5 capacitors, photocell and transistors. Thanks to the clamping system, the young electronics builder can assemble these parts completely independently and without prior knowledge to the following functional devices:

Burglar Alarm Systems, Amplifiers, Automatic Parking Lights, Humidity Indicators, Acoustic Relays, Morse Exercise Machines, Brightness Controls, Timers, Others – a total of 21 electronic devices and many interesting circuits.

With additional boxes the possibilities extend to the MW radio with loudspeaker. Proper engineers work with the same parts: all the boxes in the Philips Elektronik series are equipped with the most modern parts of today’s electronics in their original form.

 

IMG_3778IMG_3777IMG_3776IMG_3784

 

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Minerva Tempocord

IMAG0039
Minerva Tempocord

A multi-band radio receiver from the year 1957 is the Tempocord of the company Minerva. The company Minerva was founded in Vienna in 1919 and began in 1924 with the production of radio receivers. The radios were initially made under the name Radiola or Aeriola. It was not until 1926 that the receivers were built under the name Minerva. The name Minerva was used until 1972.

The device here refuses any service after being supplied with the mains voltage. Thus, a first error is found quickly. The mains voltage does not reach the transformer. The reason for this is the mains fuses, which protect the transformer from all poles. Here are both broken. Probably because the transformer tap was clamped to 220V … Rectification and smoothing capacitors are fine.
 
IMAG0038
a look inside the paperfuse
IMAG0037
paper fuse
The fuses, however, are wrapped in paper security wires, which are wrapped at the ends each with a brass clip. Due to the lack of availability of these old fuses, the fuse holders located on the Trafoprint have been swapped for current ones and reinserted. After carefully raising the supply voltage, the receiver was again able to elicit sounds …

Technical Data:

 
  • Manufacturer brand: Minerva-Radio Wien
  • Model:  Tempocord
  • Construction year: 1960
  • Typ: Radio receiver (postwar receiver)
  • tubes: ECC85 ECH81 EF89 EBF89 EM81 EABC80 EL84 EZ80
  • Operating principle / construction: Superhet receiver IF 480/10700 kHz
  • 2 NF stages . 11 FM circles and 6 AM circles
  • wavebands: longwave, medium-wave, shortwave and ultrashortwave
  • Supplyvoltage: 110V, 130V, 150V, 220V,  240Volt
  • Speaker: dynamic permanentmagnet-ovalspeaker
  • Wooden housing with dimensions: (BxHxT)55 x 32 x 25 cm

(sources: wikipedia)

IMAG0040 IMAG0041

(the device was provided for documentation purposes by: Berti)

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