Renzo Dal Bo

Hi Eremitage, Yes, my control box works only connected to the Visacustic Control Unit and a direct connection is impossible. The speed of all Visacustic projectors can be controlled through the Braun Control Unit by means of voltage levels sent to the TCA955 integrated circuit. The Control Unit is designed to receive two types of input signals simultaneously. A square wave signal from the projector, generated by an optoelectronic sensor connected to the shutter. The second type of signal was 1000 Hz pulses, originally thought to come from a special AV tape recorder with an additional recording head. The Braun Control Unit is able to process these signals, and compare the number of 1000 Hz pulses with the number of frames processed by the projector. If the comparison reveals any differences, the Control Unit is able to vary the speed of the projector until the difference is zero. Typically the biggest differences are at the projector start, but the Control Unit is able to reset them in a 2/3 second interval, and then maintain the synchrony between the 1000 Hz pulses and the projected frames. If we now think of replacing the tape recorder with a 1000 Hz pulse generator at a very precise frequency, regulated by quartz, we also get that the projector speed will be extremely precise. Even some Bauer projectors (610,525 and P8 models) have an optoelectronic sensor that allows the TCA955 integrated circuit, which they are equipped with, to regulate the projector speed through a feedback process. However, these signals are used internally in the projector and are not also sent to an external socket, as in the Visacustic projectors. Furthermore, the Bauer projectors lack the ability for an external control unit to communicate a reference voltage level to the TCA955 integrated circuit, in order to be able to continuously vary the projector speed. For this reason, Wolfgang Tuille (aka Pedro) had planned a series of modifications to the electrical circuit of these Bauer projectors to implement the missing parts and make the projectors compatible with an external control unit created by him, completely similar to the Braun Visacustic Control Unit.

Good evening to all the members of this wonderful forum, which I have been following for several years, even though I do not speak German, but with the help of automatic translators. I apologize immediately if I write in English, which is a language that I express myself better with. I would like to give my contribution on this topic, based on my experiences. First of all, being a fan of Braun Visacustic projectors, I can guarantee that it is already possible to build an external device that is able to generate 1000Hz pulses that can drive the Visacustic projector, by means of the Visacustic Steuergeraet control unit, with a maximum error of between 1 and 2 frames/hour. I myself have made some for myself and for other enthusiasts, with which I have re-dubbed several films in my language, even on entire 240m reels, without any interruption, due to the loss of synchronism from the unit that supplied the audio to be recorded (almost always a computer). Device that does not require any modification to the projector or the Visacustic control unit, but can be directly connected to the Steuergeraet unit, through the 6-pole din socket. The Steuergeraet control unit is also able to recover, especially at the start of the projector, any difference between the number of pulses generated by the external device and the number of frames shown by the projector, thus maintaining the synchronism between the two devices. For those interested, I can provide links to the videos on my Facebook page, relating to the tests I carried out myself. As for the modifications to be made to the Bauer projectors, which mount the same TCA955 integrated circuit for speed control, to make them similar to the Visacustic projector, capable of accepting external synchronization pulses, via an external control unit, it had already been solved by Pedro, in particular with his latest creations. Pedro built some devices that internally contained a copy of the Visacustic Steuergerat circuit and that, at the same time, integrated a 1000Hz pulse generator and an ESS pulse generator both driven by quartz, in addition to other specific features. This made it possible with a single unit to drive several projectors including Elmo GS1200, Visacustic, without any circuit modification, but also Bauer 610 and Bauer P8, which however required circuit modifications to make them compatible. In fact, for these latter projectors, in addition to the control unit, Pedro provided special PCBs, to be connected to the original circuit of the projectors, in order to accept the signals of his external unit (which were mostly variable voltage levels to regulate the speed of the projector through the TCA955). Together with the PCBs and other accessories such as sockets and switches, to make the modifications, he also provided detailed instructions to make them yourself. Unfortunately I have never been able to find a Bauer 610 or Bauer P8 projector with such modifications made, to be able to describe them better, but only some photos of the PCBs. Perhaps there are people in this forum who own these "modified" Bauer projectors and are able to describe them in more depth. Renzo

Gilt dieses Angebot auch für mich als Italiener, wenn ich die entsprechenden Versandkosten bezahle? Lass es mich wissen, danke. Grüße. Renzo.