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Analogue  Modular  System  A-100







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Owners Manual

Voltage Addressed T&H

The A-152 is a very useful switching and T&H (Track & Hold) module. It combines a voltage addressed 1-to-8 multiplexer and 8 fold T&H that can be used as an analogue shift register too. The active in/output is displayed by a LED.

The digital output of the currently addressed step outputs "high", the remaining digital outputs are low.

Instead of voltage control, a clock/reset controlled addressing of the active step is possible. The rising edge of each clock signal causes an advance to the next state. The rising edge of the reset signal resets to step 1.








Doepfer A-152

Basis principles:
The sum of the voltages coming from the manual Address control and the CV input define the currently addressed step of the 3 sub-devices. If the module is controlled by clock and reset the control voltage has to remain unchanged as the CV control has priority over the clock/reset control (e.g. simply turn the CV control fully counterclockwise and do not touch the Address control knob).
Sub-device #1 is the bidirectional 8-fold multiplexer (kind of an electronical 8-fold rotary switch). Bidirectional means that it works into both directions like a mechanical rotary switch: the common socket may work as an output that is connected to one of the 8 inputs that are e.g. connected to modulation or audio sources. But the common socket may even function as input. In this case the signal applied to the common socket is output to the currently addressed single socket. The voltage range of the in/outputs to be switched is the full A-100 voltage range -12V....+12V. All A-100 signals can be switched without any restrictions.
Sub-device #2 is the addressed 8-fold T&H / analogue shift register. The signal at the common T&H input is connected to the addressed T&H output. As soon as a new output is addressed the last voltage is stored at the output (Track&Hold function). The T&H section of the A-152 allows the emulation of the "toggling T&H" function of the Buchla module 266 "Source of Uncertainty". Only the first two T&H outputs of the A-152 are required for this application.
Sub-device #3 is the digital output section. The digital output of the currently addressed turns to "high". All other digital outputs are low. The digital outputs can be used to trigger e.g. envelope generators or to control the reset input in the clocked mode to reduce the number of addressed stages.

Note: In contrast to the Sample&Hold (see S&H A-148) the output voltage follows (i.e. tracks) to the input voltage as long as the corresponding stage (1...8) is active. Just when the stage is deselected the last voltage is held.
The "Common T&H Input" socket can be normalled by jumpers to the "Common Switches In/Out" socket, i.e. the common T&H input is connected to the common switches In/out socket as long as no plug is inserted to the "Common T&H Input". This allows a multiplexed T&H, i.e. each T&H output has a separate signal to be sampled. It is also possible to modify the T&H outputs for S&H function. If S&H (Sample&Hold) is chosen the voltage applied to the common input is sampled immediately when the output in question is adressed. T&H (Track&Hold) is similar but in this case the output follows the input as long as the output in question is addressed. The voltage is stored not until another output is selected.