This can draw them in line to an acceptable dynamic range for your mix. His trace is. Free Tools for Electronics Designers, EAGLE Libraries. The original one was built on Vector 3662 plug board. This is my take on the VCA. I opened up the MG-1 and adjusted this, but unfortunately it made no difference at all. The CEM rev. com Here you can find all the datasheets that we have added over the years. DIY Modules for Arduino, Raspberry Pi, CubieBoard etc. There are two VCOs and a ring modulator. has only CEM VCO and VCA even the ju8 has no curtis filters. I wrote in some of my math off to the right, I'm not sure if it's actually doing what I says it's doing. The capacitors C19,20 are there as level shifters, so that a 5V shift on the input is transferred to a 5V shift on the base of the transistor, so it will give a -5V to 0V swing on the emitter on each pulse, charging the 22uF capacitor up to 0V and thus giving, via the diodes D11,12. No-CA3080 Guitar Compressor - The TDA7052A is a readily available amplifier chip (Farnell. Nuts & Volts May 2003, Ray Marston - Understanding and Using OTA OP-Amps - Part 2. It has a reputation for being very noisy. ROLAND/KORG Transistor VCA Based on Roland JX-3P and Korg MS10/20/Polysix VCAs. I had converted the clip control to a trimmer to keep the pedal at 5-knobs. Dual Log/Linear VCA Page 1 PDF. The VCA stage (around the 3080) is quite different, with the FET there being used to output buffer the OTA and to provide negative feedback to reduce distortion. Hello fellow Wikipedians, I have just modified 3 external links on Operational transconductance amplifier. 1-888Call CA3080. since the buyer asked that the finished product be powered by a standard 'center-positive' 9vdc supply, i would also have to build a 'charge-pump' circuit. Luckily it is not very complicated to switch between AC and DC coupling. "So the development spec for the LM13600 was that it needed a schematic to train someone in IC layout. Because this one is for my Next Generation Formant project i started with the original Elektor Formant VCA schematic and added my changes to the design. Board of the Simple VCAs: Complete module: Hints. So I decided to make a PCB and module for my Next Generation Formant project. Both revisions uses 2 CEM3360 _DUAL_ VCA per voiceboard for Crossmodulation- The older revision usesr IR309 filter like in JP4, JP8, Juno60 etc. The capacitors C19,20 are there as level shifters, so that a 5V shift on the input is transferred to a 5V shift on the base of the transistor, so it will give a -5V to 0V swing on the emitter on each pulse, charging the 22uF capacitor up to 0V and thus giving, via the diodes D11,12. The Steel King/Jazz King uses transistors in the last stage opamp feedback, this looks like a better circuit to me, and the FM could take that mod easily. A-115 or A-163) as even these module can be used to process audio or (slow) clock/gate. OTA stands for Operational Transconductance Amplifier, which is a chip like a VCA except its output is variable current, not voltage. The first thing you may notice is there are three signal inputs on Thomas' schematic. Re-inventing the Voltage Controlled Envelope Generator The problem is all too well known: You can build a decent voltage controlled envelope around an OTA like the CA3080, plus the usual control logic for a normal ADSR circuit. Voltage Controlled Amplifier/Mixer. Therefore one needs to know if a VCA used is AC or DC coupled. There are two VCOs and a ring modulator. The distortion sound effects circuit of claim 1 in which said semiconductor amplifier is a voltage controlled amplifier having a gain control input, and in which means are provided for developing a gain control signal proportional to the modified signal and means for applying the gain control signal to the gain control input, said gain varying. Another marked difference was in the VCA circuits. To study the schematic, you can check it out on Dirk's page. Voltage Controlled Amplifier. Four envelopes which are Roland 100m clones. The early stuff used a CA3080 OTA for both VCA and summing audio. There are very, very few guitar pedals that offer all five; most have threshold and level only. hello all, I am looking for a low-cost and "not-that-accurate" voltage controlled amplifier for one of my revamped projects. Here is a tremolo effect I made this weekend. 49 Easy Electronic Projects for Transconductance & Norton Op Amps [Delton T. The board is laid out to accept either the original R-Ohm BA662 OTA chip, the excellent BA662 clone part from 'Open Music Labs', or a my own VCA design based around the CA3080 OTA and a discrete buffer circuit. The VCA stage (around the 3080) is quite different, with the FET there being used to output buffer the OTA and to provide negative feedback to reduce distortion. Depending on exactly what you are shooting for, there are a number of tricky approaches, including diode ring (bridge) multipliers, FETs as voltage controlled resistors, pulse width. BYOC’s 5 knob compressor is a clone of the Ross Gray Compressor pedal with some extensive extra features. This is the same circuit as the CA3080 VCA 1, except for the output stage. 4v 9 8 19 18 b c vca module 704-a,b,c,d roland 700 redrawn : yusynth. If you're making a 1970's based synthesizer, you can use many different VCA circuits. This VCA block diagram was inspired by the classic Korg MS20 semi-modular synthesiser. 49 Easy Electronic Projects for Transconductance & Norton Op Amps [Delton T. Most OTA devices are now considered obsolete, such as the CA3080 and CA3280. Sensing level at the input. has only CEM VCO and VCA even the ju8 has no curtis filters. I wanted a decent DC coupled audio VCA to process audio as well as control voltages. (OTAs) like the CA3080 and LM13600 that are often used to create multipliers, but usually just 2-quadrant. Improved VCA (CA3080, LM741). I just took a picture from the Inside of my Oberheim OB8. His trace is. A couple of years ago a friend of mine introduced me to the world of modular synthesizers at a school where he was enrolled, where they had a pretty big, original ’70s Serge with cherry-picked set of modules (I’m assuming) as well as an original Buchla 200 series system from that era. Printed by hand on Gildan Premium shirts. Time to look for a replacement. vca out dc bal. English: Conceptual schematic of the 1963 Fender tremolo effect built around a vactrol. The Waveulator Harmonic Waveform Bender Schematic Differential modulation of the VCA's Ec+ and Ec- ports greatly reduces "carrier" feedthrough. A-115 or A-163) as even these module can be used to process audio or (slow) clock/gate. 6V and +15V. Since LM13600/LM13700 is a dual amplifier the second one is configured as a VCA with manually set control voltage. I managed to successfully reverse engineer it by deduction from the AR317 schematic (Aries designers did their maths!), and Dave Brown independently reached the same. Jörgen's DIY VCA shootout. Schematics Well, most schematics of my Formant systhesizer come from the book 'Formant MSS2000' by H. Finally the Polaris does have the ancient CA3080 VCA on the main output. Just used the 3080 exactly. The HA2500 op ap is acting as the. To study the schematic, you can check it out on Dirk's page. Craig used a dedicated chip (the NE571 compander chip) to cover the voltage follower and VCA portions of the circuit. I just took a picture from the Inside of my Oberheim OB8. normally AC coupled signals) as well as slowly changing CV voltages (e. Expo convertors, Oscillators 1,2 & 3 and VCF are here. The hard-to-find/easy-to fake ua726 diff pair has been replaced with a CA3046 with no loss of performance. the blue jack of a PCO) and feed it into pin 3 of U16 (CA3080). What we have here, in ef­ fect, is the usually difficult-to-build and expensive repetitive circuit that is the core of any quality polyphonic sys­. Theres also Thomas Henry's page which has some great DIY circuits, the VCA-1 uses a CA3080. Therefore one needs to know if a VCA used is AC or DC coupled. It says in their parts list that it is a "hand picked part". I looked for schematics, there are only two You can find: one hand-drawn with english/german markings, second comes from the service manual - both have errors and some missing values. OverviewThis simple synthesizer with well available chips consists of eight 10 x 16 cm printed boards, containing:1 x One board with Power supply (350 mA)1 x One board with Sample-&-hold and LFO circuit2 x One board with VCO and exponential converter circuit1 x One board with 2 ADSR circuits1 x One board with VCF circuit including exponetial converter for tracking filter1 x One board with VCA. Another example is a divider (e. Let's start with the signal input. Imagine the musical breakup of a Red Llama crossed with an analog synth and you are close. Depending on exactly what you are shooting for, there are a number of tricky approaches, including diode ring (bridge) multipliers, FETs as voltage controlled resistors, pulse width. Aries AR-316 Documentation (compliments of Michael Gilbert) This is a simple module with three adjustments for linear gain, exponential gain, and CV rejection. com A Low-Cost VCA Limiter. A conventional op-amp (a) is a fixed-gain voltage. This one contains an easily-digestable introduction to the CA3080 Operational Transconductance Amplifier, including circuits for a simple VCA, VCO and a ring modulator. Note that all diodes shown are really diode connected transistors as in Fig. The task of the module, its voltages and controls are shown by the amplification symbol (triangle) and lines on the front panel. It's a very late model (after 1983) where Oberheim discarded the CEM3360 VCA and went back to a CA3080-OTA-based VCA, like. Control feedthru can be minimized, but this minimum is still more than for a good semiconductor VCA. net 2009 r1 100k r2 100k r3 100k r1 b r2 b r3 b-+ 2 3 6 5 7 4 ic1 ca3080 b-b+ b+ b+ r4 150k r5 100k r6 100k r7 1m r8 560 r9 560 0 10k d1. Perhaps you can lend a hand? So, I'm the most technically advanced (which don't say much :cool: ) of my friends, and 1 of them has this Realistic MG-1 Moog synth that I was handed, to clean up. The input is fed into an ADC channel to be rectified and averaged in order to detect when a note is played. If you don't have much experience with electronics, I would leave that particular board alone. I have come across the LM13600 and was wondering if anyone knew if I could just use half of it and operate it without. State-variable variant: the Polivoks VCF. This new class of operational amplifier not only includes the usual. 4 Electrical Characteristics These specifications apply for VS = ±15 V, TA = 25°C, amplifier bias current (IABC) = 500 μA, pins 2 and 15 open unless otherwise specified. OTA stands for Operational Transconductance Amplifier, which is a chip like a VCA except its output is variable current, not voltage. It doesn't always have to be that way, though. The trusty old CA3080 is used here in a logarithmic VCA. The synthesier consists of 2 oscillators, a noise generator, simple decay envelopes, VCF and VCA. I equipped my Stringz’n’Thingz with a dual voltage controlled amplifier (VCA) based on René Schmitz’ VCA-3+ design. Schematics Well, most schematics of my Formant systhesizer come from the book 'Formant MSS2000' by H. BA662 Internal Wiring. No CA3080,CA3082,LM13600 or LM13700. Modulation amount VCA for modulating the filter frequency by the triangle waveform output of the VCO. Nowadays you have to pay quite a bit for them, but their sound quality is pretty good. The LM386 headphone amplifier does impart artifacts that may or may not be considered useful. The following is a list of synths using the 3080 or 3280 OTAs for the VCA: CA3080: Moog Taurus (I & II), Prodigy, Rogue, Opus 3, (Realistic) MG-1, ARP Odyssey, Octave CAT CA3280: Sequential Circuits Pro-One Not all synths use OTA chips for the VCA. This is the same circuit as the CA3080 VCA 1, except for the output stage. The CEM rev. The reason my wheels started spinning in another direction when you mentioned the CA3080 as being the closest match for the input of the BA662 is the interesting and little-known fact that the OTA section of the LM13700/13600 IS a CA3080! The link following is a short article written by one of the chip's two designers, Don Sauer:. Once it is detected, the ramp generator is triggered and provides the control voltage for the first VCA. njm-2069ad ssm2020 ssm2024 ssm2030 ssm2031 ssm2033 ssm2040 ssm2044 ssm2045 ssm2047 ssm2050 ssm2056 ssm2300. Increasing the audio output level can be easily occur remedied by removing R102 (1K). EDP Gnat Synthesizer Schematics. Not as loud as when the VCA is open, but it's still very much. CA3080 OTAs used in orginal are replaced by. A compressor which includes a voltage-controlled amplifier first compresses the audio input signal within preselected limits, and the distortion operations are performed on the compressed audio signal to advantageously render the subsequent. Schematic: ( IMG) An op amp (IC3) generates a triangle wave, which then modulates the bias of a CA3080 op amp (the same thing that's in Dynacomps etc. The wiper of this pot travels between -0. So this VCA makes a good workhorse or general VCA. This is also ca3080 opportunity to build a better discrete OTA. In addition,these types have an amplifier bias input which may be used either for gating or for linear gain control. Luckily it is not very complicated to switch between AC and DC coupling. Of course, there can be a tendency to go overboard with this. A distortion sound effects circuit producing an output signal corresponding to an input signal but containing one of four selected types of distortion. The trusty old CA3080 is used here in a logarithmic VCA. the blue jack of a PCO) and feed it into pin 3 of U16 (CA3080). U2C removes this. vca env out vca vca env cv' s vcf env cv' s ga te vca env vcf env adsr's track cv w a ve sel & tracki ng vco1 w a ves vco2 w a ves w a ves sel w a ve select sa w2 ra w sync p vco1 i nputs vco1 w a ves vco 1 sync p sa w2 ra w vco2 i nputs vco2 w a ves vco 2 fi l t out vcf i nputs vcf env track cv w a ves sel fil ter vcf env cv' s vca env cv' s. For audio signals, you would normally use the exponential VCA (A-131), and for control voltages, the linear VCA (A-130). Voltage Controlled Amplifier/Mixer. Star Synare 3. Part Number Ca3080 Use the part number decoders to decipher the orderable part number structure iSim Simulator Quickly select supporting components, build schematics ca3080 validate designs. The LM307 and CA3080 are can style packages. net 2009 r1 100k r2 100k r3 100k r1 b r2 b r3 b-+ 2 3 6 5 7 4 ic1 ca3080 b-b+ b+ b+ r4 150k r5 100k r6 100k r7 1m r8 560 r9 560 0 10k d1. The MSK 009 Coiler VCF is one of my own designs of this type - it uses conventional LM13700-based VCA elements, with unique inductor-based integrators. The amount of amplification the VCAs provide is determined by the voltage at the CV input, and the position of the gain control, which sets the overall gain in the system. VCA DC schematic. The chip has 134000 then M5207L01 written directly below that. The VCA stage (around the 3080) is quite different, with the FET there being used to output buffer the OTA and to provide negative feedback to reduce distortion. Ibanez AD-9 Analog Delay Schematic As said, I've seen 2 versions of the AD-9 of which the later is identical to the CD10 form a filtering-component perspective. Roland mostly used the BA662 which is a VCA rather than OTA. Standing off the main analog board there we have a few more 3080's used in the Delays for the LFO's to give a nice smoothing dimension for that aspect even!. The problem with most of them is that they are either expensive, hard to find, out of production or all of the above. TEXT CHANGES Page 32, under GENERAL, step d), delete: +15V to -15VDC - Balance within 300m V of each other Page 32, under 4. Anyway, looking at the schematic, you’ll see it’s a triangle core like the Buchla 259 core we discussed in class, except a CA3080 is used instead of the “roll your own” 4-transistor OTA Buchla uses. CA3080 CA3094 300mA, CA309ducts CA3080 equivalent 5W amplifier tone riaa preamplifier circuit diagram phonograph preamplifiers schematic diagram in bass treble ca3080 amp phonograph preamplifiers ceramic 2khz CROSSOVER circuit diagram CA3046: 1994 - CA3080 equivalent. Note that all diodes shown are really diode connected transistors as in Fig. The day after I released the first version of this module, I was emailed the schematic of the Serge version, and apart from the value of the resistors, the "folder" was the same "reflector" I had designed. There's a Moog Prodigy transistor ladder filter clone and a Oberheim SEM multimode CA3080 filter clone. do you have a schematic for the tm3030 id like to get to the bottom of the vca click at some point its usually dc offset in the vca I added an offset trimpot to my custom mainboard. Board of the Simple VCAs: Complete module: Hints. Let's start with the signal input. pdf Aphex_VCA_505_card. A CA3080 type OTA is used for the VCA within the Hand Clap, in place of the original BA662. If you want to build it the way I did, then you should incorporate the dual VCA (from the last in­ stallment of Practical Circuitry) on to the same circuit board. U1a (1/2 TL072) sums up and inverts the two inputs. I wrote in some of my math off to the right, I'm not sure if it's actually doing what I says it's doing. This is only a fragment explaining the concept! Based on schematics. I tried different architectures and then decided to separate audio and DC VCA. Anyway, looking at the schematic, you’ll see it’s a triangle core like the Buchla 259 core we discussed in class, except a CA3080 is used instead of the “roll your own” 4-transistor OTA Buchla uses. 7m ldr1 ldr r32 1m j1 cv delay 100k r35 220k r34 360 d1 to pin 6 pt2399 voltage control +5v k8 k9 k10 k11 r13 47k 5 6 7 u1:b tl074 6 + 3-2 5 4 7 u3 ca3080 5 6 7 u2:b. Test of the dual S&H sections and the output low pass filters. Module List. The 2500 modules make extensive use of matched transistor pairs, and Op Amps are used in CV summing and final audio stages. 49 Easy Electronic Projects for Transconductance & Norton Op Simple VCA (CA3080, LM741) about relationship between R1-R2 and R3-R4 on the schematic found on. EMS VCS3 Type Ring Modulator Neat RM based on famous VCS Synthi. The CA3080 is obsolete and the LM13700 is currently just over $1 at Digikey. CA3080 CA3094 300mA, CA309ducts CA3080 equivalent 5W amplifier tone riaa preamplifier circuit diagram phonograph preamplifiers schematic diagram in bass treble ca3080 amp phonograph preamplifiers ceramic 2khz CROSSOVER circuit diagram CA3046: 1994 - CA3080 equivalent. The following is a list of synths using the 3080 or 3280 OTAs for the VCA: CA3080: Moog Taurus (I & II), Prodigy, Rogue, Opus 3, (Realistic) MG-1, ARP Odyssey, Octave CAT CA3280: Sequential Circuits Pro-One Not all synths use OTA chips for the VCA. The pedal has two CA3080's, and the schematic is from the version with a LM13600. The gain of the TDA chip was set too high resulting in high noise levels. Both revisions uses 2 CEM3360 _DUAL_ VCA per voiceboard for Crossmodulation- The older revision usesr IR309 filter like in JP4, JP8, Juno60 etc. The first thing you may notice is there are three signal inputs on Thomas' schematic. Several (but not too many) months ago I saw a schematic for a voltage controlled amplifier (VCA) circuit that claimed to have very low distortion in the audio range (~. SO-16 to DIP-16 without a SMD chip - assembly example. SUPPLEMENTAL LM13700 APPLICATION EXAMPLES At the time when the LM13600/LM13700 datasheet was done, management was beginning to feel that the number of applications was getting out of hand. principles behind the OTA which is commonly used in VCA’ s, VCF’ s and also VCO’ s. has only CEM VCO and VCA even the ju8 has no curtis filters. The only part which is not so easy to find nowadays is the CA3080 IC. vca env out vca vca env cv' s vcf env cv' s ga te vca env vcf env adsr's track cv w a ve sel & tracki ng vco1 w a ves vco2 w a ves w a ves sel w a ve select sa w2 ra w sync p vco1 i nputs vco1 w a ves vco 1 sync p sa w2 ra w vco2 i nputs vco2 w a ves vco 2 fi l t out vcf i nputs vcf env track cv w a ves sel fil ter vcf env cv' s vca env cv' s. Two years ago they where really cheap. The solution is quite simple. Cool, eh?! I built this using half a 13700 VCA, but it'd work equally well with the (extremely similar) CA3080 single VCA. The Control and Audio op-amp's are shown as separate I. The OTA or Operational Transconductance Amplifier is also a commonly used VCA, despite relatively poor overall performance. First of all, let's look at the goodies. The chip has 134000 then M5207L01 written directly below that. AR-316 VCA Document. There are various audio amplifier chips with DC volume control - The BTL types are best avoided, single ended amplifiers are simpler to design around. The HA2500 op ap is acting as the. Bass Comp/Limiter (cAMPus design): This is a new generation of compressor that uses the THAT Corporation 4301P VCA compression chip. Gain is about 20 with a 10V control signal. The newer MKS uses IR305 which is both VCF and VCA. Board of the Simple VCAs: Complete module: Hints. Optical compression has a reputation for having more character than a VCA or FET based compression and The Warden is no exception. Now this was sort of an interesting board. Voltage Controlled Amplifier (VCA)Image 8 shows the diagram of the VCA. The input voltage is converted to a log response by U1-C and associated transistors Q1 and Q2. I've built and tested the circuit on breadboard and stripboard. A conventional op-amp (a) is a fixed-gain voltage. Therefore one needs to know if a VCA used is AC or DC coupled. CA3080 CA3094 300mA, CA309ducts CA3080 equivalent 5W amplifier tone riaa preamplifier circuit diagram phonograph preamplifiers schematic diagram in bass treble ca3080 amp phonograph preamplifiers ceramic 2khz CROSSOVER circuit diagram CA3046: 1994 - CA3080 equivalent. Where our older compressors were based on the CA3080 or the LM13700 and are perfect for single coil guitars, the new Keeley Bassist Compressor has no problems with active pre-amps and line level input signals!. but I've bought a couple PCBs from them and frequently use their schematics. Unfortunately i dont have a schematic of the voiceboard-version with CA3080, my scheme only shows some MFC6040. Sensing level at the input. Therefore they are directly suited to bass guitars. Also in this issue I have included a re-hash of the Penfold ADSR. These are basically VCA's cores. To study the schematic, you can check it out on Dirk's page. The first thing you may notice is there are three signal inputs on Thomas' schematic. lin width exp offset exp width response exp lin 13 14 10 green red +14. Such a circuit detects when the output signal increases above a preset limit and reduces the gain of the circuit to cause the. Nowadays you have to pay quite a bit for them, but their sound quality is pretty good. CA3080 VCA 1. Bass Comp/Limiter (cAMPus design): This is a new generation of compressor that uses the THAT Corporation 4301P VCA compression chip. The first thing you may notice is there are three signal inputs on Thomas' schematic. The clock circuits in the crash, ride and hi-hat circuits each require a 4011 quad NAND IC, and this IC must be an un -buffered type for the oscillator to work correctly. Here you can find datasheets and schematics for loads of synths drum machines, effects, etc etc. is an improved version of the CA3080, and incorporates input linearizing diodes that greatly reduce signal distor-tion, and have an optional buffer stage that can be used to give a low impedance output. Most OTA devices are now considered obsolete, such as the CA3080 and CA3280. I tried different architectures and then decided to separate audio and DC VCA. Here's the original VCA, with the blue marking on the 3080 presumably to show that it has been selected for low CV feed-through. The parts in the design are not critical, you can use substitutes for the transistors (2N3904) or the silicon diodes (1N914). I think I used CA3080's for the four VCA's. Perhaps you can lend a hand? So, I'm the most technically advanced (which don't say much :cool: ) of my friends, and 1 of them has this Realistic MG-1 Moog synth that I was handed, to clean up. Roland mostly used the BA662 which is a VCA rather than OTA. Might be an interesting alternative to compressors based on obsolete CA3080 OTA. The first OTA provides the log response and the second one the linear response. These are basically VCA's cores. Control feedthru can be minimized, but this minimum is still more than for a good semiconductor VCA. Increasing the audio output level can be easily occur remedied by removing R102 (1K). At first. It acts as the VCA for the 303, and was replaced with the very similar BA6110 in the x0x. vca out dc bal. A VCA is used to control the amount of feedback. The first OTA provides the log response and the second one the linear response. This is a VCA, application taken from Nuts & Volts magazine I think (don't have the article). Its in two parts of which this is the first. IC2A sums up the external and internal audio signal. The THD in the Elektor Formant VCA is about 1% and the noise to voltage ratio is not that good either. The following shows three levels of saturation from soft to hard: Waveulator Harmonic Waveform Bender Oscillogram The Waveulator is a zero-attack zero-release limiter:. I've done some looking on both mouser and digikey as well as some Google searches and cannot find a datasheet for it. The problem with most of them is that they are either expensive, hard to find, out of production or all of the above. I haven't done extensive measurements, but I estimate it to be about what an untrimmed CA3080 VCA will show. Four envelopes which are Roland 100m clones. Therefore one needs to know if a VCA used is AC or DC coupled. I’ ve re-jigged the schematic a little to make PCB layout easier, reduced the values of the. I wrote in some of my math off to the right, I'm not sure if it's actually doing what I says it's doing. The input is fed into an ADC channel to be rectified and averaged in order to detect when a note is played. pdf (an article) DBX 2150 Application notes Dbx 202 VCA - schematic and data NTP M-100 Discrete opamp, 1978 More versions of NTP M100 Schematics. These are basically VCA's cores. It is referred to as "pack 3" in the service manual. I'm working on a schematic for a pedal and have come up to this IC. It's also my very vague recollection that it might have been by Bob. Note also that the two PNP mirrors are somewhat more complex than the NPN mirrors. It would be a major redesign to put in a completely different VCA. (OTAs) like the CA3080 and LM13600 that are often used to create multipliers, but usually just 2-quadrant. No matter how low I turn everything down, you can still hear everything on. The circuit is very simple and represents a kind of simplified Formant-VCO: Everything which is not absolutely necessary, was omitted. Both the NJM13600 and NJM13700 are still available from New Japan Radio, so I thought they would be good OTAs for experimentation. pdf), Text File (. Another small booklet by Thomas Henry. Contact me if you have the rest of the schematics for this beast. More about the tremolo once we get to it. IC2A sums up the external and internal audio signal. The CV inputs operate from 0-5V to go from off to fully on. Also included are schematic updates and servicing guides. Let's start with the signal input. In this particular synth EG voltage is actually a reference voltage for sampler's DAC, so it becomes a component of audio signal (it is somehow similar to VCA control voltage bleedthrough). The parts in the design are not critical, you can use substitutes for the transistors (2N3904) or the silicon diodes (1N914). The following is a list of synths using the 3080 or 3280 OTAs for the VCA: CA3080: Moog Taurus (I & II), Prodigy, Rogue, Opus 3, (Realistic) MG-1, ARP Odyssey, Octave CAT CA3280: Sequential Circuits Pro-One Not all synths use OTA chips for the VCA. Just used the 3080 exactly. There is no official documentation of the circuit and indeed it was blocked out on schematics, presumably because it is almost identical to the ARP 2500 VCA's expo converter. The VCA circuit also allows the builder some choice in the construction. The part is a low-cost, space-saving solution for multi-channel VCA applications. The VCA stage (around the 3080) is quite different, with the FET there being used to output buffer the OTA and to provide negative feedback to reduce distortion. There is also one offset pot per VCA to adapt negative cvs. UNDERSTANDING AND USING 'OTA' OP-AMP ICs by Ray Marston 58 N UTS & V OLTS Everything For Electronics Take a look at Operational Transconductance Amplifier (OTA) op-amp principles and at practical CA3080 OTA circuits in this opening episode of a two-part mini-series. VCA-1 Circuit Theory. Tim Stinchcombe's Synth Stuff EDP Gnat Synthesizer Schematics I originally bought one of these out of idle curiosity - having read all about the Wasp and its use of digital inverters in the analogue section, I couldn't resist buying a Gnat (a 'Special' in fact) when the opportunity arose. That is, the part number must. This module uses the CA3080 as the voltage controlled gain device, driven using a trick originated by Walter Jung and documented in Electronotes. I know very little. DIY Modules for Arduino, Raspberry Pi, CubieBoard etc. My beloved Octave CAT won't shut up. In addition,these types have an amplifier bias input which may be used either for gating or for linear gain control. The first OTA provides the log response and the second one the linear response. The D100 is a small quad VCA based around the SSM2164 VCA chip from Analog Devices. The VCO's are based on the Oberheim SEM but with Moog temp stability mods. For me, the Attack control seems like it's going to be a set-and-forget control. That 3080 overdrive contributed to the raw sound of early Oberheims. Here is a tremolo effect I made this weekend. THAT Corporation unveils the new THAT 2162, the company's first dual Blackmer® voltage controlled amplifier (VCA) IC. This includes the A simple OTA like the CA3080 will become very distorted if the differential input signal. I managed to successfully reverse engineer it by deduction from the AR317 schematic (Aries designers did their maths!), and Dave Brown independently reached the same. Notable Features: Added attack knob. Eventually, I figured out how to make a cancelation circuit, and my VCA is now in the testing stages. The VCA circuit also allows the builder some choice in the construction. No matter how low I turn everything down, you can still hear everything on. VCA DC schematic. Board of the Simple VCAs: Complete module: Hints. There are several others on the main page as well. There are two VCOs and a ring modulator. If your Ernie Ball or other volume pedal exhibits scratchy pot problems or tone loss, this circuit will correct the problem. 1% without any adjustment. It refers to a specific circuit design based around the CA3080 chip (or a modern replacement for it like the LM13700. The Thomas Henry VCF-1 documentation is for personal use only and may not be published without permission of Thomas Henry or Scott Stites. This is based on the latest schematic. The Star Synare is a cool looking synth, like a rubber UFO! It can be triggered by hitting the top pad with a drum stick , the sound is modified by the knobs around the edge. The lower end is taken to just below 0V to guarantee the VCA is turned off. Last of the OTA's There has been a lot of fearmongering from the electronic music crowd for a long time about electronic music parts going out of production. OTA stands for Operational Transconductance Amplifier, which is a chip like a VCA except its output is variable current, not voltage. My modular synth is all perfed (!!!) from scratch. The VCO's are based on the Oberheim SEM but with Moog temp stability mods. Board of the Simple VCAs: Complete module: Hints. The first OTA provides the log response and the second one the linear response. A conventional op-amp (a) is a fixed-gain voltage. vca out dc bal. THAT Corporation unveils the new THAT 2162, the company's first dual Blackmer® voltage controlled amplifier (VCA) IC. Let's start with the signal input. Eng PGCE Oakley Sound Systems Looking at the bottom right quarter of the schematic is the common section. IMO, it pretty much makes previous compressors pale by comparison if you're going for a clean, uncolored comp/limiter. In the VCA the same OTA is used as in the VCF. I looked for schematics, there are only two You can find: one hand-drawn with english/german markings, second comes from the service manual - both have errors and some missing values. State-variable variant: the Polivoks VCF. The original specifies two CA3080 OTA chips. With the Engineer's Thumb you can adjust all these parameters very easily to suit your taste; in most cases only a single resistor needs to be changed (see schematic). The inputs to the buffers are grounded and outputs are open. This is a VCA, application taken from Nuts & Volts magazine I think (don't have the article). The newer MKS uses IR305 which is both VCF and VCA. --- Log opened Sun Jul 01 00:00:32 2018 2018-07-01T00:01:19 Cracki> uh no 2018-07-01T00:01:24 vampi-the-frog> but it doesn't transform it from PDM to I2S or anything 2018-07-01T00:01:31 Cracki> the audio_dac_out is also referenced to ground 2018-07-01T00:01:47 Cracki> and it doesn't touch the PDM_OUT stuff that's lowpassed into AIN4 2018-07-01T00:01:54 Cracki> PDM is a digital signal 2018-07. I've got a very technical question about the Moog ladder filter: Why so many different implementations of the output buffers ? Sometimes a single OTA is used (CA3080 Taurus 1), sometimes two separate op amps are used (LF353 double, MG-1, Rogue), sometimes no op amps are used (Minimoog D discrete transistor pairs), sometimes a combination of discrete transistor pairs and an OTA (Prodigy). This page relates to Musical circuits, schematics or diagrams. 13700 → 3080 raw PCB. Nowadays you have to pay quite a bit for them, but their sound quality is pretty good. This is an example of one of the better wired modules. Guitar Compressor Schematic >>>CLICK HERE<<< "Ross Compressor" and I came across the General Guitar Gadgets website. CA3080 VCA 1. Star Synare 3. Trashofonium. vca balan 20k 50k 33k agno volume vrio 50k lg lj5d lj6 4069 ca3080 r32 680r vca-out agno agno r33 100nf agno r38 107 18k agno vca-out r124 123 3k d nd u23a lm386 line out dgnd speaker dgnd r88 47r phones dgnd c28 + 220uf 125 1 or c42 47nf 4071 u29b e41e 4071 4069 l29a 4071 u28b 4081 4071 u40a u29d 4071 4081 1.