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Topic: Voltage controlled amplifier

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	Hearing aid amplifier - Patent 4396806
		The amplifier is programmably adaptable through the use of a monolithic programmable switch array using, for example, semiconductor fuseable link technology to preset digital-to-analog converters voltage controllable levels of the amplifiers and compressors of each channel according to a digital control input.
		The outputs of the second voltage controlled amplifier 88 are mixed into a single channel, for example, at the input to a buffer amplifier 90, and fed through an output line 56 to the output amplifier 14 and thereafter to a speaker 16.
		The voltage signals for controlling the amplifiers 80 and 88 and the compressor 84 are generated by the coefficient selector 34.
	www.freepatentsonline.com /4396806.html (3891 words)

	Voltage-controlled amplifier - Wikipedia, the free encyclopedia
		A voltage-controlled amplifier is an electronic amplifier that varies its gain depending on a control voltage (often abbreviated CV).
		The gain of the amplifier then depends on the light falling on the LDR, which is can be provided by an LED (an optocouple).
		The gain of the amplifier is then controllable by the current through the LED.
	en.wikipedia.org /wiki/VCA (124 words)

	Synthesizers.com --- Q108 Amplifier
		When controlling the Amplifier with a Q106 Oscillator, patch its output into Control Input #1, Set the Gain control to 5 and set the Control Input #1 Level to the desired volume.
		One example of this is to use the velocity output from a Keyboard Controller to control the amplitude of an Q109 Envelope Generator which in turn controls the output amplifier.
		When simply amplifying audio signals you'll just use one of them, but for controlling the amplitude of modulation signals you may be able to use the two inverted signals to perform interesting control functions such as alternating between two different sounds.
	www.synthesizers.com /q108.html (645 words)

	Noise reducing apparatus - Patent 4430754
		Accordingly, since the control voltage level varies according to a level expansion characteristic corresponding to the level variation of the level compressed signal, the noise within the level compressed signal applied to the signal level expansion circuit is subjected to level modulation by the signal level expansion circuit.
		The characteristics of the weighting circuit 20, the amplifier 21, and the rectifying circuit 22 are respectively selected to characteristics which are the same as the corresponding characteristics of the weighting circuit 13, the amplifier 14, and the rectifying circuit 15.
		The gain of the voltage controlled amplifier 30 is K/G where G varies according to the added control voltage E.sub.0 and K is a coefficient of the voltage controlled amplifier 30.
	www.freepatentsonline.com /4430754.html (3651 words)

	[No title]
		It is an oscillator whose pitch (or frequency) is controlled by an input voltage.
		Voltage is an electric charge, or potential, between two points, one being of higher relative voltage than the other is. A 1.5-volt battery has 1.5 volts of differential between the positive and negative end, for example.
		In keyboards, where VCA's are common, the voltage is often either tied to the note number played (higher notes might open a low pass filter) or to attack velocity (the harder the note is played the more the filter is opened).
	www.nathanspage.com /wftd/wftd_v.html (1517 words)

	Synthesis Technology - MOTM-110 Ring Modulator/VCA Module
		A VCA is an amplifier whose gain (output voltage) depends on a control voltage.
		The VCA is linear, meaning half gain is +2.5V, quarter gain is at +1.25V, etc. This is the most common form of VCA, since the driving control voltage is usually the output of an Envelope Generator (EG), whose output is not linear, but exponential.
		Normally, a VCA is designed for unity gain: a +5V control voltage means the input signal is simply "passed through".
	www.synthtech.com /motm110.html (417 words)

	The Moog Synthesizer
		Start with fixed control voltage on the A unit at 0 and use the frequency range and vernier on the b units to set the desired interval.
		This amplifier is differential, meaning it is the difference between the upper and lower signal input that is amplified.
		In linear mode the signal amplitude is porportional to the control voltage.
	arts.ucsc.edu /ems/music/equipment/synthesizers/analog/moog/Moog.html (1818 words)

	Voltage Controlled Oscillator - (Site not responding. Last check: 2007-10-20)
		The VCXO001 is a voltage controlled crystal oscillator.
		The MC100EL1648 is a voltage controlled oscillator amplifier that
		Voltage controlled crystal oscillators typically employ a varactor diode to vary the frequency of...
	voltage.faasv.com /index.php?k=voltage-controlled-oscillator (755 words)

	THAT Corporation's the History of VCAs
		The voltage-controlled amplifiers found in most recording consoles and analog effects products are based on the "Blackmer gain cell" developed by David Blackmer of dbx, Inc. The original dbx 202 "Black Can" VCAs, which can still be found in operating consoles today, have been around for over 20 years.
		The VCA Associates VCA did not have an exponential control law, but had better thermal characteristics, since it was fabricated as an IC.
		These VCAs are equal or superior to their predecessors in every regard, and in particular, do not exhibit the rising distortion at higher frequencies characteristic of VCAs built on a junction isolated process.
	www.thatcorp.com /vcahist.html (824 words)

	Voltage Controlled Amplifier (Site not responding. Last check: 2007-10-20)
		A voltage controlled amplifier accepts a voltage at its input and outputs an increased voltage proportional to its gain setting.
		An amplifier in an analogue synthesizer which changes its amplification according to the size of a control voltage.
		A transient envelope is often the source of the control voltage.
	www.sfu.ca /sca/Manuals/ZAAPf/v/vca.html (131 words)

	Product Folder : VCA610 - Wideband Voltage Controlled Amplifier
		Wideband Voltage Controlled Amplifier (Rev. A) (vca610.pdf, 247 KB)
		The broad attenuation range can be used for gradual or controlled channel turn-on and turn-off for applications in which abrupt gain changes can create artifacts or other errors.
		The high-speed, 300dB/ï¿½s, gain-control signal is a unipolar (0V to ï¿½2V) voltage that varies the gain linearly in dB/V over a ï¿½38.5dB to +38.5dB range.
	focus.ti.com /docs/prod/folders/print/vca610.html (363 words)

	Glossary of Technical Terms for Sound and PA Engineers - Dictionary of Electronic Terminology - A to Z listing
		A fader with a VCA in its case arranged so that in manual operation the slide of the fader controls how much control voltage is sent to the VCA and therefore controls the channel gain.
		Similar to a voltage controlled amplifier except that the amplifier will, with no control voltage sent to it, have no gain and no loss; as an increasing control voltage is sent to it, the amplifier reduces gain (causing a loss of signal strength).
		Full name for VCA Fader (a fader with a VCA in its case arranged so that in manual operation the slide of the fader controls how much control voltage is sent to the VCA and therefore controls gain.
	www.testing1212.co.uk /v.htm (1101 words)

	Voltage-controlled filter - Wikipedia, the free encyclopedia
		The purpose of the filter is to cut off the unwanted overtones, and leave only the wanted frequencies of the sound.
		A VCF is an example of an active non-linear filter: however, if its control voltage is kept constant, it will behave as a linear filter.
		A VCF allows its cutoff frequency and Q factor to be continuously varied; it usually gives a lowpass response, but may also be switchable to allow highpass, bandpass or even notch responses.
	en.wikipedia.org /wiki/Voltage-controlled_filter (170 words)

	4QD-TEC: Voltage controlled amplifier circuit
		In truth this, like many (most) VCAs is really a current controlled amplifier but there is really not too much difference since if you want to turn a CCA into a VCA you simply feed the current input from a voltage via a voltage to current converter (a.k.a.
		Performance control range: The maximum range of the control is determined by the performance of the op-amp.
		It is not always convenient to control a set of gain stages from one potentiometer - you may wish to use a signal - the output of a previous stage for instance.
	www.4qdtec.com /cca.html (748 words)

	PAiA 2720-1 VCA Pg.1 (Site not responding. Last check: 2007-10-20)
		The 2720-1 Voltage Controlled Amplifier provides the synthesist with a versatile means of shaping the amplitude contour of synthesized sound.
		The gain of the amplifier module is dependent on the sum of the voltages at three control inputs.
		Two audio input jacks allow the VCA to be used as a mixer/amplifier and weighting of the audio inputs allows one signal to have a 3 db.
	neolase.lasers.org /PAiA/2720_01/page_1.htm (93 words)

	Voltage Controlled Amplifiers and Audio Technology
		A Voltage Controlled Amplifier is a three-terminal device with a signal input, a signal output and a control voltage input.
		THAT Corporation VCAs are characterized by an exponential control characteristic (gain varies directly in decibels -- dBs -- with control voltage), extremely wide dynamic range, and low signal distortion.
		These VCAs are made from the same patented silicon wafers as our 2181s, but are pre-trimmed during wafer processing so they require no adjustment (trimming) to achieve their guaranteed performance.
	www.thatcorp.com /vcas.html (204 words)

	Subtractive Synthesis- Basics, Waveforms, Filters, Envelopes, Modulation, Other Features - Yala Abdullah
		The Filter section of a synthesizer may be labled as VCF (Voltage Controlled Filter) or DCF (Digitally Controlled Filter).
		AMPLIFIER ENVELOPE - The amplifier section on a synthesizer may be labled as VCA (Voltage Controlled Amplifier) or DCA (Digitally Controlled Amplifier).
		To "modulate" is to exert control or affect or influence or shape.
	www.geocities.com /SunsetStrip/Underground/2288/t2ansynt.htm (4599 words)

	SYNTH SECRETS
		Indeed, so fundamental is the VCA that it has its counterparts in every type of synthesis: digitally controlled analogue synths have 'DCAs', while pure digital synths and samplers have all manner of time-variant amplifiers ('TVAs'), operator levels, and heaven knows what else.
		As you can see, I have placed a VCA in the control signal path, and this is in turn controlled by a CV that is itself controlled by an attenuator.
		Figure 10 is similar to Figure 9, except that the CVs are controlling a low-pass filter, not an amplifier.
	www.soundonsound.com /sos/jan00/articles/synthsecrets.htm (2923 words)

	OBERHEIM 2, 4, 6, 8 VOICE SYNTH ARCHIVE PAGE AUDIO PLAGROUND SYNTH MUSEUM
		All the essential circuitry necessary for a complete synthesizer voice is included: two voltage controlled oscillators (VCO's), a voltage controlled filter (VCF), two envelope generators, a low frequency oscillator (LFO) and a voltage controlled amplifier (VCA).
		Upon detection of a note depression, control signals are directed to an Expander Module as determined by the keyboard logic and the settings of the keyboard switches.
		That is to say, it is not enough to have four oscillators only to produce four part polyphony, but rather four complete voltage controlled synthesizer systems are needed, each one including not only oscillators, but also a filter, two envelope generators and a voltage controlled amplifier.
	www.keyboardmuseum.org /ar/o/ober/v.html (1911 words)

	Subtractive Synthesis- Basics, Waveforms, Filters, Envelopes, Modulation, Other Features - Yala Abdullah
		An Amplifier is used to control the loudness of the sound over a period of time so as to emulate a natural instrument.
		This is controlled by a parameter labled as "Cut-Off Frequency" (or "Cut-Off" or "Frequency").
		Apart from controlling the Amplifier, envelopes can also be used to control other sections of a synthesizer.
	groovit.disjunkt.com /analog/subs/2ansynth.htm (4463 words)

	Method And Apparatus For Removing Or Defeating Effects Of Copy Protection Signals From A Video Signal at ... (Site not responding. Last check: 2007-10-20)
		The method of claim 8, wherein the step of controlling comprises reducing the gain of a voltage controlled amplifier during said presence of said copy protection signals.
		The apparatus of claim 17, wherein the modification circuit comprises: a voltage controlled amplifier responsive to said control pulse for increasing an amplitude of all areas of said copy protected video signal except those areas defined by said control pulse.
		The apparatus of claim 17, wherein the modification circuit comprises: a voltage controlled amplifier responsive to said control pulse for decreasing an amplitude of the areas of said copy protected video signal defined by said control pulse.
	www.theworldwiz.com /docs/method_and_apparatus_for_removing_or_defeating_effects_of_copy_protection_signals_from_a_video_signal.html (4375 words)

	Another Dual VCA (Site not responding. Last check: 2007-10-20)
		The function of this dual VCA is very similar to the other one.
		Its purpose is to offset whatever control voltage you are using to control the VCA.
		This highlights the difference between the log (on the left) and linear (on the right) response to the control voltage.
	www.musicfromouterspace.com /analogsynth/newdualvca.html (317 words)

	Plural mode envelope generator for voltage controlled amplifier (US3971284)
		A plural mode envelope generator in which a basic time constant circuit is coupled by selector switches to a plurality of envelope generating means which function under the control of one or both of a keydown detector and a legato pulse generator.
		a voltage controlled amplifier for gating said electrical tone signals to an output circuit; and
		Electronic musical instrument capable of modulation controlling a second keyboard section tone signal in accordance with a first keyboard section tone signal
	www.delphion.com /details?pn=US03971284__ (517 words)

	TLN-132 Dual Voltage Controlled Amplifier (Site not responding. Last check: 2007-10-20)
		Both channels are identical and feature: separate linear and exponential control voltage inputs with reversing attenuators, a gain control for adding a constant value to the linear control input, and a bias control for adding a constant value to the exponential control input.
		EG Response - This example demonstrates the difference between the linear and exponential control voltage inputs.
		The control signal is from an MOTM-800 EG.
	www.tellun.com /motm/diy/tln132/TLN-132.html (431 words)

	Design Ideas
		As an example: vary the control voltage from 0 to 5V to change the gain from 1 to 10 V/V. Amplifier ideas: An opamp where one of the gain resistors is made up of a JFET or a SPICE Switch device (voltage controlled resistance).
		Or, a transistor differential pair whose emitter current is controlled by an external voltage.
		Suppose you need to design an amplifier for a thermistor sensor that outputs +0.1 V / deg C with the output equal to +2.5 V at +25 deg C. Amplifier ideas: A great place to start is the Linearized Thermistor Circuit.
	www.ecircuitcenter.com /CircuitIdeas.htm (428 words)

	electronic music
		For example, if a Voltage Controlled Amplifier (VCA) were being modulated by a Low Frequency Oscillator (LFO), the result would be a periodic increase and decrease in the audio level of the signal.
		The three main voltage controlled modules in an analog synthesizer are: Voltage Controlled Oscillator (VCO), Voltage Controlled Filter (VCF), and Voltage Controlled Amplifier (VCA).
		These are external controlling devices used in conjunction with a main instrument or controller.
	www.electronicmusic.com /index.cfm?fuseaction=dictionary&letter=a (479 words)

	Product Folder : VCA810 - High-Gain Adjustable Range, Wideband, Voltage-Controlled Amplifier
		It provides a differential input to single-ended output conversion with a high-impedance gain control input used to vary the gain over a –40dB to +40dB range linear in dB/V. Operating from ±5V supplies, the gain control voltage for the VCA810 will adjust the gain from –40dB at 0V input to +40dB at –2V input.
		This 40dB/V gain control is accurate within ±1.5dB (±0.9dB for High Grade), allowing the gain control voltage in an AGC application to be used as a Received Signal Strength Indicator (RSSI) with ±1.5dB accuracy.
		Zero differential input voltage gives a 0V output with a small DC offset error.
	focus.ti.com /docs/prod/folders/print/vca810.html (588 words)

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