#1793

[@synthnerd4539]

For those asking, the CEM3340 is back in production again, by Curtis themselves (the Rev G), but also by Alfa (AS3340) who are also making many of the other CEM devices, among others.

[@AdmiralQuality]

And Coolaudio/Behringer.

[@hintoninstruments2369]

The data sheet for this IC contains several exaggerations that cannot be realised in practise. e.g. Large Sweep Range 50,000:1. Only if you bypass the temperature compensation and drive Q1 directly! The precision multiplier is only one quadrant which is limited to about 10 octaves or 1024:1. Not all outputs are fully buffered. It does not run on +/-15V supplies, the maximum voltage across the IC is 24V. Nearly all applications of this IC incorrectly implement the scale adjustment using the TC calibration instead which means that the TC does not work. Most applications of this IC used microprocessor corrected tuning. Read the data sheet text carefully, it does not describe the diagrams shown , but everybody blindly copies the diagrams. Then read the Alfa application notes. Zener diodes are not a temperature stable reference and are usually noisy. It is better to use an external -5V reference. You are wrong about waveform glitches not mattering, when used at low frequency for modulation they are very annoying. There is no spec on the worst case and it varies IC to IC. Q1-3 are not current mirrors, they form a standard exponential converter with an extra output. The Curtis chipset was actually customised analogue arrays never designed specifically for this use and still are. Doug Curtis worked for the company that made them so he had insider knowledge and was able to wring the best out of them and surpassed the performance and reliability of the rival SSM ICs. The modern Alfa version is an ASIC reverse engineering the functionality.

[@robinbrowne5419]

Where I used to work our boss did experiments on his breadboard at lunch time. He often made really weird sounds by hooking up a speaker to some chips and a pot. It sounded like ghosts or space invaders had invaded the shop :-)

[@patricktuchais7596]

The circuit around A2 is also a log converter, necessary to follow the musical scale

[@chrisharper2658]

Kind of reminded me of a few chips I tinkered with: the Teledyne 9400cj and the Intersil ICL8038c. Have fun!

[@DeadManWalking4574]

HFT trimmer is to compensate for the increasing emitter resistance in the exponating transistors Q1Q2Q3 at increasing frequencies.

[@fromgermany271]

He missed the Q1Q2 exponential function completely. The diagram even showed „linear FM“ for the alternative input to the opamp. That should give a hint that there is something „non-linear“ as well. But I would assume he’s not (technically) into music and did not recognize that 1 octave difference is just double frequency and so the 1V/Octave voltage needs to go to an exponentiation stage. He’s more into MHz and GHz, so what 😉

[@Symplegades]

I haven't found a north American source for these, but you can get them from either Electric Druid or Thonk, both of which are (I think) in the UK. They are not cheap; Thonk currently has them at $16.75 each, and Druid at $15.20. Obviously, prices will vary as the exchange rate of euro vs dollar changes.

[@IMSAIGuy]

www.amplifiedparts.com/search/node/as3340

[@arnoldgrubbs2005]

Not sure if you have done a chip of the day on the Curtis 8044 chips, but it would be an interesting video. Designed a long time ago by Jack Curtis, K6KU. Not sure if he was the head of the company or it was a family thing, but I am there is some interesting stuff there. I remember these were big in home brew'ed keyer circuits when I first started in amature radio..

[@fredmitchel1236]

Fantastic...can't wait to watch. Meanwhile work work.

[@TheEmbeddedHobbyist]

Got a few of these a while back. They are still being produced ut off hand i can't remember by who.

[@darkwinter7395]

Actually there were quite a few digital synthesizers in the '80s... the DX7, for example.

[@IMSAIGuy]

The DX7 was quite special. Lots of FM mathematics in that one.

[@TranscendentBen]

The figure I heard was a quarter million DX7's were sold. Just that one model killed off all those analog-chip-based polysynths (and thus the chips themselves), as well as a couple other keyboard instruments, the Rhodes electric piano and Hohner Clavinet. All of these other instruments are now collectible at high prices, but you can still get a DX7 for well under a grand.

[@fromgermany271]

@@TranscendentBen DX7 and analog polysynths both have their place in music. They are different in features, non is a better version of the other.

[@Dennis-uc2gm]

Great explanation of the operation. I wondered if this is the same outfit that made the 8044 keyer chip ?

[@jamesmorton7881]

DDS with multiplying DAC. Total control. Like the Outer Limits.

[@headpox5817]

The folks who designed this chip (and the partners to it) were seriously clever.

[@DeadManWalking4574]

Doug Curtis, one person.

[@AnalogDude_]

Some advice not to use the onboard zener to prevent the chip heating up.

[@StepDub]

Care to elaborate?

[@AnalogDude_]

Well, rather than injecting -15V you inject -5 Volt and the internal zener on pin3 isn't turning on, thus the chip doesn't heat up and starts to drift when you play it.@@StepDub

[@StepDub]

@@AnalogDude_ interesting. thanks.

[@AdmiralQuality]

I'd like you to do about 4 more hours on this one. ;)

[@jamesmorton7881]

Why fool around, DDS direct digital synthesis. ❤❤

[@Madness832]

What's the difference between the 3340 and 3345?🤔

[@mephistowalzofficial9970]

I think it is the same die but different pins brought out to the user.

[@nickcaruso]

are these in production? I googled but it was unclear to me.

[@AdmiralQuality]

Coolaudio (Behringer) now make clones.

[@PWMaarten]

Yes, they’re in production again. Also, Alfa Rpar has a clone the AS3340.

[@viperwizard491]

AS3340

[@wolpumba4099]

*Abstract for a 5-Year-Old* Imagine a special music box that can make different sounds. This music box has a tiny heart inside called a chip. The chip makes the music go up and down, high and low, just like singing! To change the music, you can turn a little knob, just like turning the volume up and down on a radio. This music box chip is special because it was used in lots of cool old music machines called synthesizers. *Key points:* * *Tiny chip makes sounds.* The chip is like the heart of a music box. * *Sounds go up and down.* It makes triangle-shaped sounds. * *You can change the sound.* Turning a knob changes how fast the music plays. * *Special for old music machines.* These chips were important for special music machines a long time ago. *Abstract* This transcript describes a KZbin video about the CEM3340 voltage-controlled oscillator (VCO) chip. Here's a summary of the key points: * *Historical Significance:* The CEM3340 was an iconic analog chip used in many famous synthesizers from the 1980s, such as the Prophet 5 and Roland Jupiter-6. These synthesizers were polyphonic, meaning they could play multiple notes at once, requiring multiple VCO chips. * *Functionality:* The CEM3340 is a versatile chip. Its core function is to produce a voltage-controlled waveform whose frequency can be adjusted with an input voltage. Beyond that, it also offers: * Multiple Waveform Outputs: Triangle, sawtooth, square, and pulse * Pulse Width Modulation (PWM) * Frequency Modulation (FM) * Internal Temperature Compensation for stability * *Modern-day:* The CEM3340 was discontinued long ago but has seen a resurgence in popularity due to the love of analog synthesis. It is now re-manufactured and used in DIY modular synthesizers and other projects. i used gemini

[@IMSAIGuy]

Sounds go up and down. Wiggle Wiggle

[@davidkclayton]

​@@IMSAIGuy we don't wiggle wiggle here😅

[@IanNature7]

🦦 you explaining me curtis chips 🐬 so much thx 🙏

[@IanNature7]

🦦 on a day were you got nothing to do 😆 maybe you can explain us the vcf 3320, too 🦋🐬