The CMS 1036 Dual Sample & Hold/Random Voltage module is a functional circuit package designed for use with the CMS series 1000 Electronic Music Modules. The module contains two sample and hold circuits, two random noise generators, and two voltage controlled pulse generators. The 1036 is usually used in conjunction with CMS/ARP voltage controlled oscillators to produce random tone sequences, scales, arpeggios and programmed melodic patterns. The module can also be used to control voltage controlled filters, amplifiers, etc.

A sample and hold circuit has a signal input, a signal output, and a sample command input. When a pulse is applied to the sample command input, the output signal voltage immediately assumes the same value as the input signal voltage. In the case of the 1036 sample and hold circuits, this process takes about 10 microseconds. After the sample command pulse, the output signal voltage will hold at that same level until another sample command pulse is applied. During the holding period between pulses, the input signal has no effect on the output signal. In the case shown in Figure A, a sawtooth waveform is applied from an external oscillator to the "Ext Sig" input of a 1036 sample and hold. Sample command pulses can be generated by pushing the "Single Sample" button, applying an external pulse (as from an oscillator or keyboard trigger) to the "Sample" input (with the "Trig/Gate" switch set to "Trig"), or by using an internal clock pulse generator.

There are two separate clock pulse generators. The frequencies of the clock pulse generators are determined by the front panel "Clock Freq" knobs and range switches. An external signal applied to the "Clock Freq Mod" inputs will also affect clock frequency. The 2 toggle switches directly beneath the range switches are the clock routing switches that determine the destination of the clock signals.

The clock (a) routing switch on the left assigns the clock pulse (a) as follows: Left position connects clock (a) to sample and hold (a). The center position is (off). The right position assigns clock (a) to both the (a) and (b) sample and hold circuits

The clock (b) routing switch on the right assigns clock pulse (b) as follows: Left position connects clock (b) to sample and hold (a). The center position is (off). The right position assigns clock (b) to sample and hold (b).

The "Clock Pulse" output is a 10 volt pulse that corresponds to the sample period of any sample command pulse reaching the sample and hold circuit. The internal clock, the "Single Sample" button, or external pulses all produce pulses at the "Clock Pulse" output. Usually this pulse can be used to trigger envelope generators, sequencers, and so forth.

When a sample command pulse is received from the clock, "Single Sample" button, or external pulse, the output voltage appearing at "Out (a)" or "Out (b)" assumes the same value as the input voltage. In the case of Figure A, a sawtooth wave going from 0 volts to +10 volts is sampled at irregular intervals by the application of sample command pulses.

Any external signal which one desires to sample must be applied to the "Ext Sig" inputs. The knobs associated with the "Ext Sig" inputs are used to attenuate the incoming signal.

The output voltage from the sample and hold circuit will usually be a series of steps or discrete voltages. The output signal shown in Figure A is typical. Normally this output signal is used to control voltage controlled oscillators, filters, amplifiers, and so forth. If a waveform is sampled at a high enough frequency, however, the output signal can be used as an audio source.

In addition to sampling external signals, the module 1036 has built-in random signal generators. By advancing the front panel knobs labeled "Int Random Sig", noise can be applied to the signal input of the sample and hold circuits. When this random signal is sampled by the application of a sample command pulse, the output signal is a series of stepwise random voltages, as shown in Figure B. If an external signal is also applied, the random signal and the external signal will be mixed internally before being sampled.

When an external sample command pulse (as from an oscillator) is applied to the "Sample" input, two different results can be selected by the "Trig/Gate" switch. In the "Trig" position, the input pulse is differentiated and the leading or positive-going edge of the external pulse triggers the sampling circuit for 10 microseconds. The duration of the external pulse under these conditions is immaterial. When the "Trig/ Gate" switch is in the "Gate" position, the output signal of the sample and hold circuit will track the input signal as long as the external sample command pulse is positive. As soon as the pulse ends and the voltage at the "Sample" input returns to zero, the sample and hold circuit will store and hold the last value of the input signal voltage before the sample command pulse returned to zero. Figure C shows an example; when the sample command pulse is high, the output signal tracks the triangle wave at the signal input. When the sample pulse goes to zero volts, the output signal voltage holds at the voltage which was present when the sample command pulse dropped to zero.

THE 1036 SAMPLE & HOLD CIRCUITS ARE BUILT FOR HIGH SPEED OPERATION. THE SAMPLE COMMAND PULSE CAN BE CLOCKED AT AUDIO FREQUENCY FOR COMPLEX EFFECTS. ALSO THE SAMPLE & HOLD CIRCUIT IS CAPABLE OF PROCESSING AUDIO FOR GRANULAR DIGITAL EFFECTS.

ELECTRICAL SPECIFICATIONS:

INPUTS:

• SAMPLE & HOLD SIGNAL IN = +/- 10V
• SAMPLE COMMAND INPUT = 0 TO 15V, 8 V THRESHOLD
• CLOCK CV INPUT = APPROXIMATELY 1V PER OCTAVE
• CLOCK SYNC INPUT = 0 TO 10V, 8V THRESHOLD

OUTPUTS:

• SAMPLE & HOLD SIGNAL = +/- 10V ( 20V PP )
• ALL CLOCK OUTPUTS = 0 TO +10V

POWER REQUIREMENTS:

+ 12 volts @50 ma, regulated to +0.1%.

SIZE SPECIFICATIONS:

MODULE DEPTH: 1.75 inches

MODULE WIDTH: 14HP

e-mail: filter@discretesynthesizers.com

Phone: 912-727-2195