Progress with Elektronic Wien lathe

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Hello everybody!

Now that some time has passed since my last post, here some pictures of the progress with my Electronic Wien lathe... . If you have the problem that your own cutting machine only has one speed, you can run a synchronous motor at other speeds very cheaply, even without a frequency converter: You should never throw away your old 100V amplifiers. In my basement I still had an obsolete 120W mixing amp from Klein & Hummel (absolutely no HiFi), which I supplemented with a cheap Chinese LF generator to form a kind of motor power oscillator. The EW synchronous motor was switched from 220V to 110V. The amplifier now supplies 3 frequencies for the speeds 33, 45 and 78 via the LF generator, namely 21.4 Hz; 29 Hz and of course 50 Hz (the Elektronik-Wien lathe originally runs at 50 Hz, so only 78). Now one can also do cuts at 33 and 45. The applied voltages then depend on the chosen frequency to avoid magnetic saturation of the motor armature. So at 33 rpm and 21,4 Hz its only 20-25V. So it has less torque and now the question is if it´s sufficient just for embossing or even for cutting. However, the direct drive motor does not manage frequencies below that - I've tried everything, it refuses to work at 16 rpm. The whole setup now lives in an old flight case and was allowed to move into the living room. A CD can currently have a recording capacity (at 78 rpm) of approx. 2 minutes. Of course everything lo-fi and mono with a self-cut gramophone needle. The results are satisfactory at 45, at 33 I still have to experiment a little (better needle, maybe electrically heated). The inverse RIAA-Pre is still under construction (see first picture).
Cheers,
Martin

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