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RussianAudio recorders Televisions, video Tube radios NEW Other rarities My works


Olympia DG 402




Used Google translator

     Olympia DG 402. This is probably the latest model of the recorder with recording on magnetic disks. Judging by the markings on the details it was made in 1974, when the cassette recorders were no longer a novelty. Of course this recording format has its advantages, but nevertheless, the mass production of such a device in the mid-70s is surprising. Its advantages include the ability to quickly find the right place of recording and the ability to send the discs by mail, but you can make only 10 minutes of recording on such a disc.
     The recording technology is similar to the tape recorder, but the recording is made not on a magnetic tape, but on a plastic disc with a ferromagnetic coating, on which there is a spiral groove 0.3 mm wide, along which the working part of the magnetic head moves. Probably serial production of the Olympia DG 402 was not long, and this model is quite rare, but in the previous decade, these devices were relevant and in demand. The first such voice recorder was Telefunken 600, which began production in 1962. Also in my collection there is a later and technology model Assmann TS 10, but they are all structurally similar.
     Interestingly, the microphone from the Telefunken 600 of the earliest model with a non-standard connector is fully compatible with the Olympia DG 402 recorder in the mid-1970s. By the way, this is not just a microphone, it works both as a speaker and as a remote control with the functions of turning on the recorder, turning on the playback, recording, and reversing the disc, analogue of rewinding. The recorder itself has a volume control - a recording level combined with a switch, an electric motor speed regulator, and a red button for quickly erasing a record from the entire disc. When this button is pressed above the dial, a permanent magnet extends to the width of all grooves, and when the disc is rotated, the disc is erased in a few seconds.
     The device measures 295 x 215 x 68 mm, weighs 3 kg, is powered from 220 V, 50 Hz, and has a recording function from the phone. I will add that the plastic magnetic disks Olympia DG 402 and Telefunken 600 are the same, and differ only in marking, in the first case the inscription "Olympia", in the second case the "Telefunken" logo. The electronic circuit is assembled on 11 transistors and a TAA511 chip. The amplifier uses 8 transistors BC3198 (5 pcs.), BC239C (1 pc.), BDY34 (1 pc.), And a transistor labeled S122T. The engine speed regulator uses transistors AC187, BF194, and a transistor labeled S122T.
     The device works fine, and it's really convenient to use. Especially useful was the function of reverse rotation of the disc, since this voice recorder was intended for dictating texts, and the reverse function was needed to quickly repeat the last words for the convenience of printing text on a typewriter.

Photos can be enlarged

In the kit there is a nice cover, but unfortunately there is no original microphone. I use a microphone from a similar voice recorder Telefunken 600, they are fully compatible

     Magnetic disks Olympia DG 402 and Telefunken 600 with a diameter of 155 mm are almost identical, and differ only in marking. In the first case, the inscription "Olympia", in the second case the "Telefunken" logo. Telefunken disks also have two holes, apparently for use in dictaphones with a different disk fixation. In these recorders, the disc is fixed on a rotating table by pressing it down into a hole with a diameter of 38 mm

     In the illustration to the left, the parameters of the groove of the Olympia DG 402, Telefunken 600, Assmann TS 10 magnetic disk are used. These discs are also used with the similar Traveller and Kurier dictaphones manufactured by Telefunken and AEG, respectively. However, with the original Assmann TS 10 discs, the diameter of the hole is different, but the groove parameters are the same. On the reverse side, all the disks are black. 

This recorder is made in Germany, like other similar Telefunken 600 and Assmann TS 10

In the photo above, the patch panel with the "Phone" - "Microphone"

The recording is from the edge to the center of the disc. When the tone-arm approaches the center, contacts that include a sound signal are closed. In the extreme right position, the tone-arm is fixed by a spring, the contacts of the engine control circuit are activated, and it stops. To move the tone-arm, you must press the control knob from top to bottom, while the head rises above the disc, and you can freely move the tone-arm to any position. If you move it to the extreme right of the fixed position, the disc retainer rises and you can replace it.

The photo below shows how to quickly erase information from the disk with the help of a permanent magnet

The electronic circuit of the Olympia DG 402 is much more complicated than the Telefunken 600, which is assembled with only 5 transistors

The design of the magnetic head unit is the same as that of the Telefunken 600. In one case, the erasing and universal heads are assembled. The width of the working part is 0.25 mm. Resistance of the universal head 250 ohms, erasing - 33 Ohm. Details on the construction can be found on the page Telefunken 600

I got the dictaphone in the original package