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retro technology

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)

miscellaneous and news

mini quadcopter drone … HUBSAN X4

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IMAG1395_1A new gadget from the technical area is the radio quadrocopter Hubsan X4. (thanks Ralf and Nadja: D)

Here is a short test testflight…

It is a miniature quadrocopter, the size of the palm of your hand, which turns out to be a real powerhouse. It is controlled via a 2.4GHz handheld transmitter in six axes. The transmitter can be configured in Mode1 and Mode2 (throttle on the left lever). An LC display on the transmitter provides information about the current settings and a multi-color LED shows the switch-on status and also whether there is a radio connection to the drone.

The drone is built on a very light (crash-proof) chassis that also has “recursive predetermined breaking points”. This means that in the event of a crash, part of the affected engine boom unhooks instead of breaking off. You can then simply click it back in. There is also the option of installing the training frame supplied to protect the propellers.

The power supply in the transmitter is provided by four AAA batteries. The drone itself is powered by a LiPo battery that is charged using the USB adapter supplied. You only need a USB power adapter (mobile phone charging plug) or a PC / laptop as a voltage source.

When fully charged and with moderate flight, you can achieve a flight time of just under seven minutes. Before the end of the flight you will be warned by blinking LEDs, so that you can still land safely without any problems. Recharging the battery takes just under 30-45 minutes.

As a further special feature, the drone has a small camera on board. It offers a resolution of 480p. But there is also a version with a 720p camera. The camera data can be saved directly on a microSD card. The recording is started before the start of the flight by pressing a button on the drone and should be stopped again before switching off. The result is an “.avi” container file that can be played on any PC. The image section is not very wide-angled and is just acceptable for indoor use. You also need plenty of light to get reasonably sharp images. However, this works very well outdoors.

The controls can be learned quickly with a little practice and it is a lot of fun to use.

retro technology

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

 

Mechanics hobbyist

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

Arduino, electronics hobbyist

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:

retro technology

TEDDY automatic

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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

 

 

clocks and watches

torsion pendulum clock

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A patience-related work is the restoration or repair of a rotary pendulum clock.

A rotary pendulum clock is, as the name implies, a mechanical clock that generates the clock from a pendulum rotating around its own axis. The vibration energy is transmitted here with a torsion spring (Horolovar spring), ie a very fine steel wire special alloy. IMAG1268_1 The rotary pendulum clock is also called annual clock, as due to the very slow oscillation and corresponding mechanical implementation of the escapement, a lift of the spring accumulator only once in 300-400 days is necessary.

Of course, this also requires a certain precision of the mechanical components. If something is not set correctly here, the clock will switch off after a few minutes. Even the fine adjustment of the accuracy requires some patience. And just like a clock has done to me. In an online auction house, I have a cheap ‘defective’ but purchased from the components ago complete rotary pendulum clock and immediately started to disassemble and clean the parts.

https://www.youtube.com/watch?v=yFbs3kSGvvc

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Knurled screw for the pendulum diameter

 

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suspension spring

After this work we went back to the assembly. The Horolovar feather was replaced by a new one. Now we went to the adjustments. First, I had to find out how many pendulum oscillations, more precisely half vibrations, should make the clock in one minute. At my watch (a Kundo) these are eight beats. The easiest way is to use a stopwatch to measure the time it takes to reach the 8th half-cycle. For example, if the measured time is over one minute, the watch will run too slowly and must be adjusted with the thumbscrew (the one that changes the position of the pendulum weights in diameter). Turning the thumbscrew clockwise will make the clock slower and counterclockwise faster, of course.

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Escapement with anchor plate

It should be a precision of +/- 1 minute per month possible. So a deviation of 12 minutes a year. Of course this requires optimal environmental conditions. (constant temperature and humidity, as well as a firm, vibration-free state)

 

 

 

electronics hobbyist

Surrounded by radioactivity?

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After the self-made Geiger Müller counter and the associated experiments, I noticed that there is one or the other radioactive element in our environment.

With the SOEKS 01M Geiger counter, an industrially manufactured device, I have now again “scanned” objects in the area.

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SOEKS 01M

Again, I realized that some of the old clocks in my collection are equipped with radium-painted dials. The SOEKS shows here a radiation exposure of about 1.11 microSievert per hour. The environmental load is displayed at approx. 0.14 uSv / h.IMAG1290

But in my mother’s kitchen, I found a beautiful, colorful old vase that displayed about 10uSv / h. (The thing is now in the far corner of the cellar).

It should be uranium paint. (To see orange / red painting in the video below)

 

miscellaneous and news

Taster day in technology

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In the last two days we received a visit from two young gentlemen from the fourth year of the Villach High School Sankt Martin. Mr. Martin Ungermanns and Mr. Fabian Treu came to us as part of a “taster program” of the middle schools. The two students can participate in the “world of work” and get some insights into the technology.

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deepened in the soldering work

The program included work such as assembling and soldering of electronic kits (the well-known shaker cube), a small series work (flashing of PIC microcontrollers), exposure and etching of circuit boards, milling of aluminum plates.

As conclusion of the two taster days both high school students were allowed to build up a complete “device”.

 

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Martin Ungermanns and Fabian Treu

It was a “clap switch kit” that detects a loud sound event via an acoustic sensor and then turns on a relay contact. So that this circuit can also be used meaningfully, the circuit has been extended by a self-made power supply, all installed in a plastic housing and equipped with power cable and Schuko coupling. So any consumer (eg a floor lamp, TV) can be switched on and off with this switchgear by simply “clapping” …

Arduino, electronics hobbyist

Radioreceiver in a retro look – Update: The case

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IMG-20150130-WA0000-2 It’s time! The first picture of the absolutely real wooden housing for radio electronics is here. A beautifully crafted housing made of glued elements. This work comes from Gebhard’s hands, a master carpenter from the Upper Carinthian region;)

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Housing with holes for the speakers

Jetzt kann das Nostalgie-Radioprojekt wieder einen Riesenschritt nach vorne machen.

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This will be the aluminum front panel

The case is on our table. First, the holes for the speakers were drilled. Later these should be covered by a milled aluminum panel. So the next step is to construct the milling data for the front panel. Here again the layout tool “Eagle” is used. The data can simply be exported as a “.dxf” file and imported into the circuit board plotter software.

 

UPDATE:

Barely a few minutes, I went to the circuit board plotter, imported the production data, clamped the “two-cutter cutter”, of course, the aluminum blank and off we went.

The speed for the 1mm cutter I have chosen with 60000 rpm and set the feed rate to 1.5mm / s in both axes. Cooled and lubricated was the way with alcohol.

A not negligible amount of work is, by the way, the cleaning of the plant after the work done … 🙂

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