Module A-170 contains two separate slew limiters, also known as portamento controllers or integrators. The first SL has just one joint control, which sets both rise and fall times (c. 0 …10 sec). The second SL has separate controls for rise and fall times, and can therefore be used as a simple AR envelope generator. Over and above this, you can set the overall range for these parameters, with a three-position switch, as on the full ADSRs.

Both slew limiters have two LEDs each, to show the state of the rising and falling voltages.

Additional technical remarks: If the upper slew limiter is used for precision applications (e.g. portamento/glide of one or more VCOs) a buffer (e.g. A-185-1 oder A-185-2) is recommended between the A-170 output and the VCO(s) input(s). The reason is a small voltage drop that is caused by the protection resistor at the A-170 output. An A-185-1 or A-185-2 connected between the A-170 and the VCO(s) avoids that voltage loss. For all A-170 manufactured later than May 2009 (recognizable by the label “Version 2” on the pc board) this remark is not valid as these modules are equipped with an additional voltage buffer at the output.
The lower slew limiter cannot be used for precision applications because of the voltage loss caused by the diodes of the circuit.

Module A-171-2 is a voltage controlled slew limiter with a lot of additional features beyond a simple slew limiter. It’s mostly a licensed copy of Ken Stones VCS which is in turn based on the Serge VCS.

These are the most important features:

Manual control of the Slew-Up time

CV control of the Slew-Up time with polarizer

Switch for linear/exponential shape of the rising section of the response curve

Manual control of the Slew-Down time

CV control of the Slew-Down time with polarizer

Switch for linear/exponential shape of the falling section of the response curve

Signal input: the “to-be-slewed” signal

CV Up Input, affected by the CV Up Control and the corresponding exp./lin. switch

CV Down Input, affected by the CV Down Control and the corresponding exp./lin. switch

CV Up and CV Down sockets are normalled

exponential CV input: named “V/Oct” in the original design but as it’s not really exactly 1V/Oct we will name this input probably “exp.CV”, mainly used for VCLFO/VCO applications in cycle mode or as common exponential control for both up and down times in slew mode

Trigger input: used for envelope generation or retrigger in VCLFO/VCO mode, a pulse at the trigger input will start the envelope or retrigger the VCLFO/VCO

End output: turns high as the output falls below about 20mV, turns low as the outputs goes beyond about 3.5V, in cycle mode a rectangle signal is generated

Cycle on/off switch: when “on” the End output is internally connected to the Trigger Input to generate cyclic signals like an VCLFO/VCO

Output: the signal output of the module

LED display: displays the slew limiter output signal

Typical applications:

VC Slew Limiter / VC Portamento / VC Low Pass Gate
Cycle switch = off, no trigger signal applied to Trig socket:
Voltage controlled Slew limiter or portamento generator: the signal applied to the signal input is “slewed”. The slew up and down times are controlled manually by means of the Up and Down controls, the effect of the CV Up and CV Down control voltages are controlled by the CV Up and CV Down controls, in exponential mode these controls also affect the slew shape (see symbols at the CCW and CW positions of the controls)
If an audio signal is applied an short slew rates are chosen the module works as a simple VCF/VCA combo

A/D Envelope Generator / Pulse Delay / Subharmonic Generator
Cycle switch = off, trigger signal applied to Trig socket, no input signal:
Simple Attack/Decay envelope Generator, the rise and fall times are controlled like the slew up/down times above, including the shape of the falling/rising slope of the envelope, the exp. CV input can be used to change both attack and decay simultaneously
At the End output a pulse appears as the end of the envelope is reached (less than about 20mV), this can be used as a pulse delay
If a series of triggers are applied to the VCS faster than the total rise and fall times, the module will divide the incoming signal by a whole number. In the audio range the output will be the sub-harmonic series.

VCLFO / VCO
Cycle switch = on, no trigger signal applied to Trig socket, no input signal:
Voltage controlled LFO/VCO, the rise and fall times of the waveform are controlled like the slew up/down times above, including the shape of the falling/rising slope
the exp. CV input can be used like the CV input of a VCO or VCLFO, the response is exponential but not exactly 1V/oct

A-172 is a minimum/maximum selector module and is equipped with four analog inputs and two analog outputs (minimum, maximum). The main application of the module is the processing/mixing of control voltages, e.g. random voltages, ADSR, LFO, S&H, ribbon CV, theremin-CV and similar, but even for audio signal processing the module can be used (e.g. several outputs of the same or different VCOs).

The module permanently picks the maximum resp. minimum voltage out of the four input signals and outputs these voltages to the maximum resp. minimum jack socket.
To adjust offset and amplitude for each input independently (i.e. to bring the signal into the right “position” with the desired level) we recommend to combine the module with the A-129-3 Slew Limiter/Attenuator/Offset Generator (see patch example below). The other sketch below shows the basic principle of the max/min module by means of three sine waves (e.g. three LFOs) with different frequencies and different levels.

Module A-174 modules outputs 2 control voltages generated by a spring-loaded X/Y cross potentiometer (so-called joy stick). For each output the voltage offset (zero setting) can be adjusted. Each output is equipped with 2 LEDs for positive/negative display of the output voltages. If the spring is removed for one direction the joy stick is no longer spring-loaded for this direction (as the spring is destroyed when removed this cannot be re-established !). We use a high quality joy stick made by ALPS in the A-174.

Application: manual X/Y CV control of other A-100 modules, e.g. VCF, VCA, VCO, Phaser, BBD modules, wave shaper/multiplier, frequency shifter, VCLFO, VCADSR, panning, etc.

In combination with the Dual Voltage Controlled Crossfader A-134-2 manually generated crossfades between audio or modulation sources can be realized.

The pcb is equipped with two jumpers that can be removed to obtain a voltage plateau around the center position, i.e. the output voltage does not change for a small movement range. The jumpers are labelled JP4 (Y plateau) and JP5 (X plateau). Removing the jumper activates the plateau.

A-174-2 is a modulation wheel module with two wheels. The factory setting is a spring loaded wheel at the left side with bipolar voltage output (i.e. 0V in center position, positive voltage in the upper range, negative voltage in the lower range, voltage range about -5.5 V … 0V … +5.5 V) and a wheel without spring at the right side with positive voltage output (i.e. 0V in the lowest position and positive voltage when operated, voltage range about 0…+8 V). For the spring loaded wheel a voltage “plateau” around 0 V is preset (jumper) so that the output voltage is 0 V in a small area near the center position.

By means of jumpers the factory settings can be changed. For each wheel two jumpers are available: one for the voltage range (positive or bipolar) and one for the voltage plateau around 0 V. If these settings are changed even the wheels have to be re-adjusted mechanically. Therefore such modifications should be carried out by a qualified person only. By request the module is available from the factory even with two wheels both with or without springs (additional charges Euro 10.00 for each change).
Important note for module mounting: As the potentiometer of the left wheel projects about 10 mm the rim of the front panel a 2 or 4 HP blind panel has to be mounted left from the module – unless the module left to the A-174-1 has sufficient space in this area (e.g. A-174-1) !

Module A-175 (Dual Voltage Inverter) is exactly what it says it is: two identical inverters, which will take a voltage and output it in an inverted form – so that an input of +5 V will be output as -5 V, an input of -2 V will be output as +2 V, and so on.

Two LEDs give a visual indication of the (positive or negative) output signal.

Module A-176 (Control Voltage Source) provides three voltage sources, to use wherever an extra CV is required. The top two voltage sources (CV 1 and CV 2) have controls for coarse and fine control of the voltage output; the third source (CV 3) just has the one control.
The range of the voltages output can be preset, either to 0 to +5 V or to -2.5 V to +2.5 V depending on your likely requirements. There is a jumper on the circuit board for each of the three voltage sources.

A typical use for the module would be to provide fine as well as coarse tuning for an A-110 standard VCO, (which, unlike the A-111, only has one tune control).
In general, this module will be useful whenever you need a manually controllable CV on a module which doesn’t itself have a built-in control.

Theremin module for generating a variable control voltage by approaching/removing hand to/from an antenna. The distance range is about 30 cm. Additionally the module is equipped with a Gate output with adjustable threshold level. Controls/Inputs/Outputs: antenna input, offset (knob for zero adjust), 2 x CV out, 2 x LED (for CV control positive/negative and zero offset adjust)

To simulate the original Theremin two A-178, a VCO (e.g. A-110) and a linear VCA (e.g. A-130 or A-132) are required. But of course the A-178 can be used to control other functions in the A-100 (e.g. filter frequency, modulation depth and/or speed, tempo, attack/decay time and so on).
The CV output voltage of the A-178 can range – according to the setting of the front panel controls – from -10V…+10V. The gate output switches from 0V to about +10V.

For more detailed information please look at the English user’s manual A178_man.pdf

Applications:

controlling any voltage controlled parameter of the A-100, e.g. pitch or pulswidth (VCO A-110), loudness (VCA A-130/131/132), panorama (A-134), filter frequency or resonance (A-120/121/122/123), phasing (A-125), frequency shift (A-126), resonance peaks (A-127), envelope parameters (A-141/142), tempo (A-147)
triggering of A-100 activities via gate with adjustable threshold, e.g. starting an envelope (A-140/141/142), Start/Stop of a sequence (A-155), any switching function (A-150/151)
Conversion into MIDI control change messages is possible with the A-192.
Remark: If two or more A-178 are used the distance between the modules/antennas should be at least 30 cm. Otherwise the antennas affect each other.

From August 2012 an improved version for the antenna connector is used. A so-called BNC connector is used to connect the antenna to the module (same type of connector as used in measuring equipment like oscilloscopes). Therefore the price of the module has to be increased a bit. Some mechanical and electrical skills are required to modify an existing A-178 module for the new version of the antenna connector. The module has to be disassembled. An additional hole for the new BNC connector has to be drilled or punched into the panel e.g. right from the existing antenna socket above the Offset control (the existing hole of the 3.5 mm miniature socket cannot be used for the BNC connector). Then the module has to be assembled again and the new BNC connector has to be connected to the old socket. Pay attention that an isolated version of the BNC socket has to be used. For example the BNC connectors UG1094PL, UG1094PR, UG1094W1 or UG1094W2 can be used. In Germany the connectors are available e.g. from www.reichelt.de or using e.g. the order no. 571-5413194-2 from Mouser, Farnell, RS-Online or other suppliers).

Technical Note: It’s not possible to connect the antenna via an additional cable to the antenna socket. Antenna and hand form a variable capacitor with a very small capacity in the pico Farad range. The electronics of the module is puzzled out just for this capacity range. If a cable is added the capacity range changes totally and the module will no longer work ! But it’s possible to mount the complete module with antenna at the desired position, e.g. into a small case that holds one or two of the modules. For this a longer bus cable is required. If you are not able to manufacture such a cable yourself we may offer a suitable cable upon request. Please tell us the desired length for a quotation of such a cable.

Similar control voltage modules:
Trautonium/Ribbon Controller A-198 / Foot-Controller A-177-2 / Joy Stick A-174-1 / Wheels Module A-174-2