Postbag: #37 - ETI Vocoder Parts - CMOS 4006, LM3915

[@Desmaad]

Can't wait to see the completed thing in action.

[@JulianIlett]

Desmaad Neither can I :)

[@buffplums]

You’ve really inspired me to get my electronics head on after a long time

[@markwood1705]

Looking forward with anticipation as this project unfolds. Thanks Julian as you continue to both entertain and enlighten us all.

[@edgeeffect]

I remember the ETI Vocoder and the Transendent 200... I just couldn't have dreamed of affording the parts back then but I used to like to re-read the magazine articles and dream. I'm looking forward to seeing your work on this project.

[@edgeeffect]

I quite like the sound you get on the second tap... it's got a low-fi techno feel to it.

[@Laediin]

I realize this is an older video, but for anyone in the US you can still get the CD4006 and CD4030 from NTE if you want to attempt to stick to the original design as much as possible.

[@ThingsWhichArentWork]

Nice work Julian. I'm looking forward to watching this project progress. Cheers!!

[@reggiebacci]

I looked at LFSRs a while back - the idea was to attach one to an Arduino to make a un-hijackable random number generator for encryption. The idea being that anything running in RAM would be vulnerable to malware / spyware memory dump attacks, but an off-board Arduino based jobby would be much more difficult to compromise.

[@PuchMaxi]

Cool project, greetings from the Netherlands!

[@jlucasound]

I'm from the Future!! Don't Solder the GREEN LED's IN!! They are too BRIGHT!! Oh, well, you already know. ;-) Love your videos, Jylian!!

[@Kevin-wj1do]

Just found this video and instantly subscribed.

[@csatacsibe]

2 numbers are relatievely primes if they have only one common divider, so that means they dont have to be primes, like 4 and 9

[@websitesthatneedanem]

I still have those ETI magazines somewhere!!!

[@edgeeffect]

I'd love to see them again... I used to read ETI (and Hobby Electronics, Practical Electronics, et al) avidly... I couldn't really afford any parts back then... but they provided plenty of fuel for my fantasy world.

[@smitcher]

Hi Julian, I actually did my University final year electronics project on Pseudorandom white noise generator which was basically what you have but with a selector switch to select which taps could be selected on the shift register. I also had two or three registers chained together to get the max length I needed. I then had the taps fed to a resistor network and various filter networks to get the desired rolloff curve on the specttrum analyser... Of course now you could do all of this in a 6 or 8 pin micro... Interesting project the vocoder though. I had a lot of those 80s magazines (still have i'm sure) and think I recognised it when I saw it on your videos from one of them... hmmm... up to the attic this weekend me thinks...

[@JulianIlett]

smitcher That sounds like an interesting final year project. I hope I managed to get most of this right!! Yeah, it would be fun to get that 6-pin PIC to do this instead of the CMOS logic.

[@krishna34674]

please please get into building modular synthesizers.

[@superdau]

For numbers to be "relatively prime" the numbers themselves don't have to be prime. They must not have a common factor though. So 5 (5), 9 (3*3) and 14 (2*7) are relatively prime.

[@JulianIlett]

superdau Thanks. That makes a bit more sense. I just finished the noise generator and it sounds pretty good, although there are perceptible patterns in the sequence. Now to move on to the input and output amplifiers.

[@SpringDivers]

Nice project, Julian. Let's do it. Thanks for the video.

[@0MikeG]

Nice! Have you thought about slowing down the clock to 2-10 Hz? I tried this many years ago with the SN76489's noise generator.

[@amiloduk]

Hi Julian. I have a copy of the PDF but the main board overlay is missing, have you got a copy or are you building the main board from your own design. In the PDF it say send an sae to modmags to get a copy, im sure that wont any more. id love to build this project, any help would be appreciated. john

[@liamharrison3]

Really interesting video!

[@mrgpen7850]

i would like to know how much it would cost me to buy one of each of the vocoder boards from you thank you gary

[@joohop]

interesting , i use a software vocoder in a program called reason that should be a nice unit when its up and running good luck

[@jakeypie4529]

Amazing :) keep it up I LOVE POSTBAG :)

[@alien8r33d]

Why not use the HC devices?

[@AntonVeretenenko]

I guess it's cheaper to get any 5v micro, simulate 4006 in software with interrupts for low speed clocks, and slap 4006 label over it :)

[@croonologist]

Hello: What's the country of origin of the Powertran ETI vocoder?

[@alphasnk]

Uk

[@SouthCoastMudlarks]

Sounded like an old 8 bit Atari game. Interesting project.

[@ceech123]

Would someone care to explain what does vocoder do, and why is white noise an essential part of it?

[@JulianIlett]

ceech123 Try this: www.newyorker.com/tech/elements/object-interest-vocoder

[@Ogma3bandcamp]

Loving this...

[@Coolkeys2009]

I know it goes against grain of the project but surely a micro controller would be better for implementing the logic, maybe even the LED bar graphs displays? The random sound reminds me of a ZX Spectrum game loading or 56K modem :-)

[@JulianIlett]

Coolkeys2009 I want to stay true to the original circuitry for this project, but you're right, a microcontroller could do the noise generation. In fact, I wouldn't be surprised if there's a vocoder app which models the entire thing on a reasonably fast processor (i.e. a mobile phone)

[@Coolkeys2009]

Julian Ilett Fare enough you want to know it sounds original. I wonder if microchip have any app notes for musical instruments using their dsPIC or newer microcontrollers :-)

[@jasejj]

It's a ZX Spectrum!

[@JulianIlett]

Jason james It does sound like that, or a dial-up modem.

[@ophello]

Wish you had twisted the pot while the noise was playing....

[@migry]

£1.65 including postage, how the hell do they sell it for that price! Nice videos BTW!

[@jlucasound]

You are picking up encoded communications by something.

[@jlucasound]

We are still waiting. One day you will unveil (so much for the "I" before "E" rule I was taught in school) the completed Vocoder. I CAN wait. Make it right. I think that is what you are doing, and you have much more on your "plate". That "box" is going to be awesome. You always get everything right. (Aside from crossed legs). Our secret. ;-) Julian. You have taught me so much.

[@ljmike1204]

we need cooler led,s than red and yellow

[@siliconjunkie7297]

Come on Julian, don't bodge it make a PCB for the bar graph. Show them how to do it properly.

[@JulianIlett]

Silicon Junkie Making PCBs is a whole different thing - I don't really want to get into that with this project. It'll look beautiful, I promise ;)

[@stephanstanisic2007]

HaHa! Nederland toch een beetje populair! (Use translate ;P)

[@stephanstanisic2007]

Ik had het eerder over post NL