It Works! - Microphone Preamplifier - Vocoder

[@Whigu]

Like so often it's more interesting to watch video where something doesn't work and somebody is fixing it than just a video about thing that worked.

[@mahlapropyzm9180]

It's quite some years since I realised that the only time you really learn anything useful is when you screw up and then (hopefully) fix it.

[@twentycm]

Sounds very smooth without any noise, well done

[@jimthvac100]

Your doing great making these videos Julian. Don't change anything your doing. The mistakes is how we all learn. You are really good with electronics and it make the rest of us feel better that it is OK to make mistakes.

[@ElmerFuddGun]

_"Let's see it working in action or hear it I should say..."_ You had it right the first time... let's *see it on the scope!* - 8:54 It can be easier diagnose a problem when you can see the actual problem than trying to guess what you are hearing.

[@mahlapropyzm9180]

Well, it's very honest ofyou to own up to your mistake and very educational to see it fixed (in concept) by your leg-crossing bodge. Also it was useful to see the effect of the 68pF cap. I have to admit I was screaming near the end "just get some more PCBs", but it makes sense to verify the fix before ordering them.

[@ElmerFuddGun]

The tone control is backwards. As you turn it to the left (counter clockwise) you should hear more bass and as you turn it to the right (clockwise) you should hear more of the highs. Check your radios that have a tone control and you will see that is the standard.

[@JulianIlett]

I know - it's annoying me ever so slightly. On the schematic there's a CW marking at one end of the tone control pot - I missed it :/

[@3dmaxuser]

Julian have you fixed the tone control in the new V2 board ? also want to say thanks for the heads up on jlcpcb I ordered my first pcbs about 4 or 5 weeks ago and they came out looking and working great so thanks again :)

[@MrBBea4]

Ah yes, the beauty of the $2 JLCPCB's. It so much fun designing and ordering the boards, getting them and then discovering one or two traces are in the wrong place. I have buckets of useless PCB's waiting to be turned into some sort of arts and craft projects with my kids!. FYI: the biggest problem I have found is where a PCB foot print (usually from a contributed library on EasyEDA) has the wrong footprint (schematic pin-out to pad arrangement) associated with it. Some boards are salvageable, but most end up in the G file box. Be sure to check the traces before ordering your boards. Cheerio, Barry From Canada

[@deangreenhough3479]

Well done Julian, you even make modifications with a degree of style😁🏴󠁧󠁢󠁥󠁮󠁧󠁿

[@followthetrawler]

Top Field Service Engineer bodging there

[@ElmerFuddGun]

*Sooooo much easier* to use bodge wires. *It doesn't matter where the tracks are as you are using through hole components.* Every connection has a plated through hole pad. Cut the trace and solder a wire on the bottom side going to the right pads. It is a simple fix and doesn't matter how many times you swap ICs for whatever reason it will still work. Bending IC leads can easily cause them to break and now you have to find a replacement and try it all again. - 5:37

[@ElmerFuddGun]

And frankly bodge wires look more professional than bending IC legs. It happens even on professional production boards where it can cost major dollars to redo the PCBs. And those wires won't even be noticed from the top when you are showing your friends your nicely assembled project.

[@chrisumbel3132]

"It's a power supply and it's on my bench. That makes it a bench power supply." -- I honestly LOLed.

[@MiniLuv-1984]

Good to see Murphy is in full swing in the Northern hemisphere too. Aside from the error on the schematic, nice job by the way.

[@____________________________.x]

I like the crossed pins bodge. I once had to desolder a pin, insert a tiny teflon sleeve to insulate the socket leg from the PCBs internal via, and then add a mod wire. Gawd it was fiddly. I guess the proper way would have been to cut the tracks on yours, but that would take longer. Congrats on a working module.

[@steveroberts1861]

Nomination for the Captain Backwards awards 2019. Nice work apart from small problem.

[@Richardincancale]

1/4 inch jacks for audio, RCA phono jacks for audio, 1/8 inch stereo jacks. So you’ll need 8 types of patch cables for your synth! Neat!!

[@jamesstockton7905]

One thing I noticed which may help reduce the hum is a ground flood. If you flood the top and bottom and stitch them together with vias this will vastly improve the sound quality.

[@The.Doctor.Venkman]

Love the 'Bench' Power Supply, Julian! You really had me going there as I've never, ever seen you use an 'actual' Bench Power Supply...... Lol! Ooooh, I hate those things :-) As for those bent IC power pins; I've had worse delivered from China.

[@sdgelectronics]

He got me too 😂

[@RedwoodRhiadra]

Wait till you see Clive's X-ray machine!

[@mitkopetrovik259]

Nice DC/DC converter, simetric or dual out from battery... More info for this puppy? Thanks

[@JulianIlett]

I just put a link in the description

[@HazeAnderson]

I recently did the thing I said I wouldn't do and was lucky I didn't fry my $5 component. Good job with the leg crossing fix! xD

[@jayherde0]

I also vote for swapping the end connections on the tone pot for v2.0. But then, WE drive on the right side of the road here ;-) One of the selling points of the machined headers is their reliability. They hold good, probably at the expense of repeatability? Instead of using post-it notes, can you add some text to the diagram? Or maybe both. When I work on perf-board, I put 'solder' and 'comp' on the pcb layout. Flip the 'solder' text. Components and jumper wires go on the top layer, and perf-board tracks go on the bottom layer. Then, a printout of the top layer works for a 'silk screen' to insert components. A flipped printout of the bottom comes in handy too.

[@chrispotts2010]

Yes Krzysztof Foltsman, I would also say that it would seem more natural for the tone control to operate in the opposite direction. Julian?

[@JulianIlett]

Yeah, I couldn't tell from the schematic what direction would affect which frequency - so I just went for the easiest layout. I will swap the connections in v2 :)

[@chrispotts2010]

@@JulianIlett Nice one.

[@MrBrymstond]

So why didn't we use a Pro Audio XLR connector style mic as well as the 1/4 inch?

[@ElmerFuddGun]

It is a home project. He already has the mic with 1/4". XLR will cost way more. XLR will take more space and require front panel modification. XLR uses balanced lines and thus will require circuit changes. So why bother?

[@urugulu1656]

a lot of the noise your hearing may also come from that dc dc converters switching?! maybe invenstigate on that...

[@jamhough22]

That noise will be coming from that power supply, microphone preamps are super sensative to noise, ideally they need sheilding all the way arround the thing especially with mains humm. And those power supplies will be making a tone of noise. decoupling capacitors on the supply rails and filters / capacitors would make that much better. I recently made an amp using a TDA2005, noise from other devices much further down the supply line caused some hissing, a paralell damped filter sorted that right out and even with a ebay boost converter to get the most out of it from a 12v battery worked brilliantly with no noise at all, I managed to get the ac ripple of that boost converter down to 10s of mV p-p from about 1.5V p-p

[@kardeef33317]

Was thinking that if you pull the opamp out and plug it into a free unsoldered IC socket you could use those breadboard wires with a male pin on one side and a female on the other end, you could plug the male ends in the socket on the PCB and the female ends on the socket that holds the IC. You could wire the IC to the board anyway you want.

[@BigRTKingKong]

Julian thank you, I learned something.

[@vk3hau]

86 , 92, 12, 45, 74, 68, 31, 55 ... BINGO! oh, sorry for a minute there I thought you where going to start calling out bingo numbers, hi hi.

[@drex5220]

Question: Is it best (More efficient) to Buck to 3.3volts from say 4 AA's NiMH , or Boost to 3.3v from 2 AA's NiMH twice, what gives you more run time. (being as you have one of those silly scope thingies).

[@GeorgeK356]

Chips with crossed legs? You're taking the pee, Julian lol

[@maicod]

try crossing your legs without having them contact eachother ;)

[@mUbase]

Nice work in fixing your design Julian. Crossed over legs? Im sure its all in the best possible taste! ;)

[@sdgelectronics]

I thought you were actually going to use a bench power supply. You got my hopes up

[@TheTrashcutter]

Can you please tell me the name of the power supply module for the -12V & +12V ? Thanks

[@hrawk]

Negative Voltage Dual DC12V (on ebay)

[@TheTrashcutter]

@@hrawk thank you

[@rogerfurer2273]

Dremel and razor knife to modify PCB, tone is reversed from standard: bass should be full CCW and treble full CW.

[@3dmaxuser]

I agree with you but maybe it was like that in the original unit ?

[@rich1051414]

Yeah, treble to the left is weird as hell.

[@incorporeal3793]

Completely new to the electronic hobby and looking for a way to power a car amp in home at 14.4v that doesn't involve a battery and charger. I was thinking of using a step up convertor, 1800w 40A in and 22A output. As far as the 22A output goes, when it says constant does that mean if I set the potentiometer to max it will be putting out 22A regardless of what I have the voltage set to?

[@michaeltempsch5282]

Assuming the converter is capable of limiting current (constant current mode). That means that if the load (amp) tries to draw more than the set current, the converter will turn down the voltage to compensate so that the output current doesn't go over he set limit. The converter (any power source) will never output more currrent han the load draws. This means it is perfectly OK to hook up your cellphone that came with a 5V 2.1A charger to a monster supply capable of delivering 100A at 5V. The phone wont draw any more current than from the 2.1A original charger. Another typical case of using constant current mode could be in reviving a overly disharged battery that a regular battery charger cant charge, using a bench power suply. By connecting the supply directly to the battery terminals and setting the voltage to say 4.25V for a LiIon cell, the current would initially be very high, possibly higher than what the suply can deliver. But if you set the current limiter to a low vale, say 50mA the supply will turn the voltage way down so that only 50mA is drawn and goes into the battery. As the battery very slowly charges, and its voltage climbs, the supply will continually adjust the voltage it puts out so that the current remains at 50mA (constant current). If the supply also has a constant voltage setting, it could be set to te battery's final charge voltage (say 4.25V), and once the batattery gets thereere, the upply wont furter increase the voltage but instead let the current drop below the set max of 50mA.

[@robertharker]

If someone asks about the crossed legs, just say the chip is waiting to go to the loo.

[@n8nkqrp595]

Or say "she's a proper lady"

[@SidneyCritic]

I hate it when you check something, and check it again to be sure, and still you make a mistake.

[@bk8896]

What module are you using for -12-o+12 volts supply? Thanks

[@mgrFurry]

0:54 is this some sort of dc-dc converter with symmetrical output? Where can I get it (aliexpress?)

[@JulianIlett]

I just put a link in the description

[@mgrFurry]

Thanks! Already ordered.

[@0toleranz]

Pins crossed that it works. Cheerio.

[@nicnl255]

Oh my god I couldn't stop laughing at those butchered opamps, I spat my water everywhere It's both amazing and disgusting at the same time

[@JulianIlett]

I try :)

[@tubical71]

That´s why i use perfboards....any mistake can be fixed...if you use PCBs then...you´re almost screw´d.... 07:50...that little cap stabilize the OpAmp at high frequencies, if you omit it and your power supply has some RF stuff on top of its rails then that OpAmp may be going to oscillate at a frequency where the input pins change their signs...please read the datatsheet and look out for "transit frequency" or gain-bandwith product...and there must be a graph which shows a line crossing the x-axis somewhere...that´s the point where this happens...these oscillations are nasty, and could easily damage the following stage(s)....so it needs to be adressed.... Oooh man....09:25...where should i start..?!? GET YOURSELF A DECENT POWER SUPPLY!! Julian....come on....! this noise you hear ist from your "piss-poor" D/DC converter...that´s an *absolute NoGo* (read my lips N.O-G.O.!) for audio....do you fuel your car with coffe?! no, ok then, why you use these kind of "bowa sabblie" on audio stuff, then ?!?

[@247hinkey]

Great video - gave me plenty of laughs considering your such a perfectionist. lol

[@kennmossman8701]

that makes it a bench power supply..............so much for British humour. Can I watch Dave Allan now?

[@milenedejong1400]

you could design small pcbs for those crosswired opamps . something with a dual dip8 footprint .. or maybe we can design a new opamp pinout tl072-i lm358-i ne5532-i .... maybe something exotic wit a metric pin spacing :p .

[@johnarmstrong3782]

I've been watching these vids for what seems like an age without knowing what a vocoder is or does? What is a vocoder and why would any one want one?

[@JulianIlett]

11 minute overview - kzbin.info/www/bejne/hae1ZaSBZadgY9k

[@maicod]

your opamps have their own antennae :)

[@duncanx99]

So the demons that inhabit the black art of analog even caught out the master. I tend not to risk incurring their wrath and stick to digital. An very elegant final bodge to get round the problem, though...

[@tartrazine]

0:58 you said "proper". Very naughty.

[@JulianIlett]

and I meant it :)

[@SimonCoates]

Should have built the op-amp circuit on a daughter board 😃

[@steveoddlers9696]

It's daughterboards all the way down! :D

[@rich1051414]

Better build a daughter board to hook everything together on the motherboard.

[@AW-Services]

Love your projects but PLEASE invest in your audio delivery

[@____________________________.x]

Heh, Julian is trolling me with his "bench power supply". Tsk, that doesn't count, for a start it's a switch mode which isn't the done thing for audio, and it doesn't have any meters (like to indicate that you've reversed an IC and it's drawing 2 amps...). One day you'll build one and it will be glorious in its utility :)

[@richardmckenzie8715]

One way to keep the crossed legs from shorting out is coat it with clear nail polish.

[@kennmossman8701]

plus and minus 12V, so 24VDC ???

[@kennmossman8701]

you need a Looooooooooooooooong holiday

[@urugulu1656]

make them wires isolated man. i dont want to know what happens if you short them together by accident edit watched the rest of the video and there should be any enormous dangers but it may sound awful

[@urugulu1656]

consider using a proper microphone for the screen sections as well. the differences in audio quality are awful

[@Goman1244]

You know, I thought I made a mistake once, but I was mistaken.

[@pulesjet]

I would have just cut the tracks and soldered your jumpers on the bottom of the board on the socket pins.

[@Roy_Tellason]

Wow. Just wow...

[@jparky1972]

Capton tape. Or even just a piece of insulation tape on the back leg.

[@ollieb9875]

Kapton! 😁🙃

[@Okurka.]

"Prototype PCBs for $2 (Any Color)" They don't come in bright pink.

[@maicod]

still watching but @ 6:05 looks like the pins make contact at the crossover. edit: obviously they didn't :)

[@T2D.SteveArcs]

just make a couple of 8 pin dip daughter boards flip ze pinz

[@patricksweetman3285]

Seriously comical, Julian.

That is quite sexy bodge.

[@alankingvideo]

Top bodger.

[@hectorpascal]

OMG! Get a BOX spanner for those 10mm pot nuts! One slip with the open ended spanner will have you cursing at yourself while looking sadly at the scratched panel!

[@azyfloof]

Anyone wanna tell Julian about bodge wires, or shall I? :P :P

[@JulianIlett]

I've bodged a thousand wires. Just fancied trying something different :)

[@haieknagasaki4709]

Oh this is so cool!

[@MrBrymstond]

What, no vocal track? Really?

[@kennmossman8701]

dual 741 ???????????????????????????

[@captainpugwash4100]

Pump up the volume! Pump up the volume!

[@tablatronix]

my ears! lol

[@gapadad2]

Field service upgrade.

[@JulianIlett]

Definitely :)

[@SpeccyMan]

Bodge-tastic. :D

[@kennmossman8701]

Use a PROPER PSU

[@Dana-qq3pk]

Mr Ilett . please check Facebook.thx.

[@LiveArtPresents]

waste of time and space.

[@cheeseburger251]

First

[@haieknagasaki4709]

no one cares

[@cheeseburger251]

@@haieknagasaki4709 i care

[@ats89117]

This video is a complete fail...