Microphone Preamplifier Circuit - Vocoder

[@jlucasound]

You do such an excellent job of laying things out on the breadboard and perf board. I love neat, tidy, electronics. The daughter board was an awesome idea and came out beautiful. And it works great! One step closer!!

[@mikeoliver3254]

Always happy to see a vocoder video.

[@dentakuweb]

Vocoder videos are fun. It seems to be your Winter pastime.

[@YTANDY100]

that daughter board was awesum , i use a much simpler one with a crystal and two caps + three pins for use with pics on bread board :-)

[@steveroberts1861]

Nice work on the veroboard.

[@leomarbunledaccesories7442]

Nice video and thanks Sir.. Peace from Indonesia

[@____________________________.x]

Reason #629 for using a proper linear power supply and not a noisy solar panel DC-DC lashup :) That was an awful schematic you had to correct there, good job.

[@Anvilshock]

A new vocoder video?? No way!! Is it 2068 already?? Anyhow, thank you for the practical excursion on op-amps and frequency-dependent voltage dividers!

[@JulianIlett]

To be completed THIS year :)

[@Anvilshock]

Oh, Julian!! I didn't think we were ready to advance to that level yet. It's all going so fast! :D

[@hinzster]

I bet you say that to all the girls :P

[@DustinWatts]

I removed my previous comment because I already answered my own question. It’s an active high-pass filter! 😁 Thanks for the video Julian! Btw it’s a sub-sonic low cut filter...

[@MarvinStroud3]

I do believe that you have created a pole in the right half of your s-plane.

[@westinthewest]

I counted three.

[@HazeAnderson]

Yay audio circuits!! Thanks! Fun stuff. :) I recently bought some LM308 op amps and they ... didn't work. :/ As a last ditch resort I decided to test them as if they were LM358 dual op amps ... and they WERE!! :D

[@joinedupjon]

solution to the car 'expressive' noise maker... put a speaker under your bonnet and grumble at people down your electret mic.

[@PeterCCamilleri]

Wow, 120 Hz, North American noise ;-)

[@paulgrimshaw6301]

I'm afraid you can't just work out the -3dB point by making the capacitor reactance equal to the resistance, as the voltages across the two components are out of phase. So instead you have to use pythagoras to combine the reactance and resistance, making this equal twice the resistance. The answer is -3dB at 9Hz.

[@petehiggins33]

I rather think that you can. When the reactance is equal to the resistance the impedance is equal to root two times the resistance. If the gain is proportional to the inverse of the impedance as it approximately is in this circuit then the gain is reduced by a factor or one over root two which is -3dB.

[@paulgrimshaw6301]

Ah, you're right, sorry. Power gain at half is 3dB down, voltage gain at 1/(root 2) is 3dB down. To be fair though he incorrectly talks about the gain being halved as in -3dB power gain, but not the case with -3dB voltage gain.

[@jaymercy224]

I planned to build my own vocoder for many years. I thought I'd do it this year. I am very curious to follow how your own project progress.

[@trickyrat483]

That sound.. Spinal Tap! :)

[@Xfixiateher]

What is the split rail PSU you're using on the top left hand corner? -15v and +15v one.

[@JulianIlett]

They pop up on eBay now and again, but don't sell in large quantities, so they disappear again. I just bought this item: Negative Voltage Dual DC12V -12V Power Supply Module 5-12V to ±12V For Amplifier ebay.us/1uutVv. This seller is a good one for this type of PSU.

[@beachsidetech]

Think the main purpose of the 22uF cap is not highpass, but reducing the DC gain of the first stage to 0 to aid stability for a high gain stage

[@nicolaedumitrache9246]

-3db is half power, meaning 0.7 gain, not half gain And making the capacitor reactance equal with the resistence does not double the impedance of the r+c circuit, you need to use the complex impedance sqrt(r*r+xc*xc)

[@ElmerFuddGun]

Schematic errors in magazines use to really tick me off. And this one is no exception! Look at that top line input "switch". It is drawn above the ring and also has the "tip" going to ground! Then there is another connector switch just down and to the right... what the #@$ is that doing there? How many errors do you count?!

[@JulianIlett]

Yeah, I'm annotating the PDF. I've found a couple of dozen errors so far. But it's forcing me to analyse all the circuitry in some detail.

[@ElmerFuddGun]

​@@JulianIlett - It is like the magazines assumed everyone reading the articles would just buy the PCBs direct but I would often just want to try a certain part of a project circuit out on a breadboard. You would have to wait months to see if a correction notice would be published. I love reading paper magazines but without the internet for updates/corrections it could be infuriating! Good idea with the PDF annotation. It will save others having to do it.

[@bborkzilla]

I think that's supposed to be a stereo jack. When you plug in a mono connector the "ring" terminal is grounded by the connector's sleeve, but it disconnects R4 from ground. Meanwhile the tip terminal disconnects IC1a and connects the plugs tip to RV1 wiper.

[@ElmerFuddGun]

@@bborkzilla - Oh, that makes more sense. Although the jack's ring terminal is grounded already. The tip signal then goes to one end of the RV1 pot (not the wiper). Thanks for clearing that up as it wasn't exactly obvious in the schematic to me that that was a stereo jack. It is one of those times where I would be looking at the PCB layout to see what was actually connected to what.

[@JulianIlett]

I think it's a mono jack socket. The ring connection and switch is upper left on the schematic - this just disconnects the 11k resistor from GND when a plug is inserted. The tip connection and switch is lower right - this connects the tip to top of pot RV1 when inserted. I think :)

[@taranagnew436]

i have the same headphone breakout board but can't figure out what pins need to go to what pins on a nano FYI i'm building a VU meter

[@taranagnew436]

hello?

[@sparkyprojects]

I hope in your final version you implement a baxandall tone control

[@JulianIlett]

This is similar but only requires one pot :)

[@sparkyprojects]

Actually, it's just a treble boost/cut Baxandall adds the bass boost/cut If you add this you can tune for clarity of voice plus the bass tones ;) Concentric pots are still available if you only have room for one hole btw, i noticed ETI is available on archive org as a 'page turning' resource :)

[@williamcolvin3609]

Have you worked out all the errors and created circuit boards for the project?

[@JulianIlett]

Yes, but that'll be one of the last PCBs to go to revision 2

[@aaaaaa-kc4fs]

Hi sir.i want this circuit

[@kamals4905]

Did you ever test Zero crossing detector in past if yes then please send me link Else Give me some good direction for it, I tried with 4n35,4n25,EL817,MCT2E (direct with mains 230v 50hz)but always received false reading.

[@ElmerFuddGun]

I don't recall Julian doing it. I found lots with Google though. I would suggest using a low voltage transformer to test a circuit so you can connect it to a scope and safely diagnose any problems.

[@JulianIlett]

Yeah, I did this years ago for a lighting controller - Like you suggest Elmer, I also used a low voltage transformer (split I think) and pretty much any opto.

[@Hardwarenerd]

How did you fit that big of a connector on the breadboard?.. Nice project! Waiting to see it completed

[@JulianIlett]

I show it in close-up right at the end of the video :)

[@RWBHere]

My first visit in more than a year, and you still haven't finished with the Vocoder? Will I be drawing a pension before it and the computer are completed?

[@JulianIlett]

This year I'll be more productive - I have so much more time available now :)

[@Bigalldone]

Im guessing Anthony Daniels(C3-PO) is from your neck of the woods ;)

[@JulianIlett]

Not a million miles away :)

[@Bigalldone]

@@JulianIlett Ha! What are the chances? 3720 to 1 :D

[@twotone3070]

@@JulianIlett Less than 3 parsecs then?

[@realhusky]

Damn dude, edit the volume of the noise if you're going to leave it. Eardrums are bleeding

[@JulianIlett]

Exciting or what :)

[@realhusky]

@@JulianIlett Haha, it worked better than a redbull. I went from drowsy on the bus to ready to rumble. I do enjoy the content, thank you.