Module A152 is a very useful switching and T/H module. It combines a voltage addressed 1-to-8 multiplexer and 8 fold T/H that can be used as an analog 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 even 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.

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 / analog 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 and 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.

technical details

Width: 16HP

Connections:
CV input
Clock input
Reset input
SW I/O 1-8
Common Switches I/O
S/H output 1-8
Common S/H input
Dig. outputs 1-8

Module A-148 (Dual S/H) has two identical sample and hold modules, designed to produce 'staircase' voltages.

The signal present at the sample input is sampled at a rate set by the signal at the trigger input, and held at that voltage at the S/H output.

The exact shape of the staircase depends on the sort of waveform at the sample input: NOISE or RANDOM signals produce random patterns; an LFO produces rising or falling staircase patterns.

Two LEDs for each S/H indicate the voltage (positive or negative) of the sampled signal.

For each sub-module the operation mode S/H (sample and hold) or T/H (track and hold) can be selected by a jumper.

In T/H mode the output signal follows the input signal while the trigger input is "high".

As soon as the trigger input turns to "low" the last voltage is stored.

The factory setting is S/H for the upper device and T/H for the lower device.

technical details

Width: 4HP

Connections per unit:
Trigger input
Sample input
S&H output

Module A-149-1 is the first module of the A-149-x range. In this group Doepfer presents by popular request several functions of Don Buchla's "Source of Uncertainty 265/266" (SOU) modules that cannot be realized with existing A-100 modules.

Module A-149-1 has available four different analog random control voltages that are generated in different ways.

The "Quantized Random Voltages" section has available 2 CV outputs: "N+1 states" and "2N states".

N is an integer number in the range 1...6 that can be adjusted with the manual control (Man N) and an external control voltage CVN with attenuator.

Whenever the rising edge of the input clock signal (Clk In) appears a new random voltage is generated at the N+1 resp. 2N output.

The N+1 output is capable to generate N+1 different voltage levels (or states), the 2N output up to 2N different states.

If for example N is set to 4 the N+1 output generates up to 5, the 2N output 16 different states.

The voltage steps of the 2N output are adjusted to 1/12 V in the factory. Consequently exact semitones can be obtained in combination with a VCO.

The voltage steps of the n+1 output are adjusted to 1.0 V in the factory corresponding to octave intervals in combination with a VCO.

For each output a trimming potentiometer is available on the pc board that enables the user to select other voltage steps for the output in question.

Even the "Stored Random Voltages" section has 2 stepped CV outputs available: one with even voltage distribution of the max. 256 output states and second one with adjustable voltage distribution probability.

The distribution probability is adjusted by a manual control (Man D) and an external control voltage CVD with attenuator.

With the control set fully counterclockwise most of the random voltages will be low magnitude but even medium and high magnitude voltages may appear but with smaller probability.

As the control is turned to the right (or a positive control voltage appears at the CVD input) the distribution moves through medium to high magnitude voltage probability.

The symbol at the lower jack socket shows this coherence graphically.

The voltage range is 0...+5V for both outputs of the "Stored Random Voltages" section.

For each output a trimming potentiometer is available on the pc board that enables the user to select another voltage range for the output in question.

The A-149-1 can be extended by 8 random digital voltages with the A-149-2 Digital Random Voltages module.

Technical details:
If you are interested in technical details here is some information.

All random voltages are derived from digital pseudo random generators that work with shift registers and digital feedback via exor gates.

The digital output voltages of the shift registers are added up with resistors to obtain variable stepped analog voltages.

For the N+1 output all resistors have the same value, the 2N output uses resistors in ratios of 1:2:4:8:16:32.

Consequently the N+1 output has less different states available than the 2N output.

In addition the digital shift register outputs are gated dependent on the current N voltage (sum of manual control + external CV) by which the number of possible states can be reduced.

In contrast to the A-117 the shift registers are not clocked by an internal oscillator but by the external clock input Clk In.

The generation of the "Stored Random Voltages" is similar but with different resistor values and more shift register outputs.

In addition the random voltage is processed by a non-linear clipping unit with adjustable offset that allows to modify the distribution probability of the voltage levels appearing at the lower output.

Even though the module is intended to generate slowly varying control voltages clock frequencies up to moderate audio range (about 2 kHz) can be processed.

technical details

Width: 12HP

Connections:
CV N input
Clock input 1
QRV Out n+1 output
QRV Out 2n output
CV D input
Clock input 2
SRV output 1
SRV output 2

A-149-2 is an extension module for A-149-1. It makes available 8 digital random voltages (i.e. only low/high states like a gate signal).

The outputs are controlled by the "Quantized Random Voltages" section of the assigned A-149-1 and correspond to the 8 digital outputs of the shift register that is used to generate the Quantized Random Voltages.

As the alteration of the A-149-2 outputs is clock controlled by the Clk In of the "Quantized Random Voltages" section of the A-149-1 the A-149-2 can be used to create random rhythmical sequences.

The A-149-2 requires the A-149-1 and has to be mounted directly to the left or right of the A-149-1 as an internal ribbon cable connection has to be established between A-149-1 and A-149-2.

technical details

Width: 4HP

Connections:
Outputs 1-8