Walkman City Bummler from the 80s

IMG_3810From the early 1980s comes the „City Bummler“ a mobile, portable cassette player – in short a Walkman. At that time, I received it as a Christmas present during my middle school years. The special feature of this device was a built-in microphone and two headphone ports. So you could listen to music in pairs and if you wanted to say something without having to remove the headphones (or to reduce the volume), so you had to press only  an orange colored button and the intercom was active. The device was sold as a low-priced „replica“ version of the first Walkman from Sony, the TPS-L2 which came on July 1, 1979 on the market. The citybummler was distributed by UNIVERSUM via the source mailer.

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City Bummler with a self made coverplate after the original got broken

The device was delivered in a box with headphones, cassette pocket and carrying case with strap. For operation, three AA size 1.5V batteries were needed. The volume control is carried out with two separate sliders, so that each channel can be controlled separately. Unfortunately, the city loafer has not passed the last 35 years quite unscathed. Over time, the cassette cover was broken off, which I then replaced in my youth with a homemade tinplate lid. At some point I did not like the case color and I painted the device green. (or I just had green paint at hand). At least the „loafer“ still exists and it works too.

IMG_3814I was then on the Web in search of a well-preserved, in the original state city loafer. However, the offer is extremely low and the few offers on online auction houses are not interesting because of the immense shipping costs.

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Fellow FE-1

But a compromise and at the same time a new piece in the collection is the FELLOW FE-1 Walkman. I got the most cheap and fully functional on a second-hand stock market.

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left: Fellow FE-1, right: City-Bummler
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both devices in comparison

The Fellow is also a clone of the Sony TPS-L2. It differs essentially in the arrangement of the keys of the drive.

 

 

 

 

 

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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%

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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).

 

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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

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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:

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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.

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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.

 

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Minerva Tempocord

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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.
 
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a look inside the paperfuse
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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)

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

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Multimeter analog

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Unigor 6e (ca. 1970)

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
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measuring 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.

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Scale sheet of the Unigor 6e

 

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The flame licker

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A small mechanics project occupied me this time. It is again about a hot air engine. This time not about the Stirling engine, but the so-called „flame eater“.

During the search in the World Wide Web, I found, among other things, the website of Mr. James Maiwald. Mr. Maiwald is an ambitious modeler and specialist in the field of Stirling and vacuum engines. He develops and manufactures his own models in all variants and also offers them as a kit.

More precisely, it is a vacuum motor, which is popularly also called a flame eater. He is one of the hot air engines, but unlike the Stirling engine is an open system.

Technically speaking, it is an atmospheric engine, since here the external air pressure does the work (comparable to the first gasoline engine). As a result, the maximum piston force is limited to the product of piston area and air pressure. (Wikipedia)

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Detail view slide valve

And exactly one such model (lying the flame eater) is here. As I assemble the engine and the first time commissioning is seen in the following short video …

More information and interesting models and kits can be found on the website of Mr. Maiwald: www.kellergeist71.de

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Radioreceiver in retro look – The finishing

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The wooden case is painted

Now that the front panel is milled, it can be cleaned and the engravings are provided with black paint. After the varnish has dried in the indentations of the engraving, the supernatant paint is removed with solvent. Now the entire panel could be painted with clear lacquer.

While the paintwork on the front panel is drying, it’s time again for the wooden cabinet. The mounting holes for the boards, speakers, etc. were drilled and then the wood was embedded with a slightly darker wood stain. After drying, the wooden case also gets a clear coat.

In the next step, the operating elements (switches and rotary encoders) and the LC display are attached to the front panel. The milled webs for the speaker panel are covered with black fabric. (For the fabric had to serve a T-shirt).

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The painting of the housing dried about a day. Now you can start mounting the speakers and the board.

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Installation of the speakers

 

Die Platine wird mit Abstandhaltern am Gehäuseboden verschraubt.

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Assembly of the board

 

Now a suitable power supply is missing. For this purpose, a small power supply was built, which consists only of an iron core transformer with subsequent rectification, smoothing and voltage stabilization with a LM7809, ie 9V DC. For this, a small board was made (about 5x8cm) and also built into the housing with spacers.

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Power supply 240V AC to 9V DC at max. 350mA

 

Now that everything is assembled, the amplifier metrics and levels are again set and optimized with signal generator and oscilloscope.

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Adjustments

 

The finished radio receiver now looks like this from the front …

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Radio from the front

 

und die Geräterückseite ist im nächsten Bild dargestellt:

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back

In the short video, the radio can be seen in operation:

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TEDDY automatic

IMAG1321From the years 1970-1972 the radio receiver TEDDY AUTOMATIC 100 comes from the German manufacturer ITT – Schaub Lorenz. It is a multi-band receiver that covers the wave ranges of long wave, short wave, medium wave and ultrashortwave.

It is designed for mains and battery voltage (110-127V / 220-240V and for battery operation for 4×1.5 volt size AA cells).

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The output power is 0.8 watts and is transmitted with a dynamic oval speaker.

The technical structure according to the manufacturer consists of 6AM circles and 9FM circles. The receiver principle is a SUPERHET with ZF 460kHz and 10.7MHz. The housing is made of plastic (thermoplastic) and has the dimensions of 215x127x70 mm with a weight of 1.2kg.

 

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Connection for external sources
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Switch for receiving frequency

 

 

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