New PCBs - LM3915 LED Audio Level Meter - Vocoder

[@Sheevlord]

Word of caution - some of these kits have blown LM3915 chips that always lights up the first LED as lit no matter what. When I replaced the chip with another LM3915 I bought separately it worked as intended.

[@JulianIlett]

That's worth a try.

[@Roy_Tellason]

I bought four of these kits and all of them won't ever light LEDs 2 and 3. Replacements are supposedly on the way... :-(

[@DepressedNOF]

As an audio guy and musician I'm allways upset by false implementations of volume meters. Green range is from -infinity to 0dB Yellow range is from 0dB to < Peak ONE red for Peak wich is the distortion limit of the underlaying circuit. But thats something the world will never learn ^^

[@____________________________.x]

@@sdffsdafdsfsdfsd - well I care, I didn't realise there was a proper format until NOF posted.

[@JulianIlett]

The LM3916 is a VU meter

[@____________________________.x]

So is NOF talking about a peak meter? (I'm not an audio guy, just wondering what is correct here)

[@DepressedNOF]

​@@JulianIlett yes. The datasheet tells us that pin 1, 18-13 is the -20 to 0 range and pin 12-10 is the +1 to +3 range. The point I'm trying to make here is that if you look at professional audio gear e.g. mixers you typicaly see green in the range up to 0, yellow above 0 and only one red for the peak. Because red should indicate that the signal is too strong for the circuit. Thats a binary state. It can't be partly too stronge hence there is no need for 2 red LED's. I understand that it is not reasonable to mesure the distortion limit of your vocoder and adjust the Vref accordingly. It's nothing world breaking, just something I get slightly upset about.

[@n3ttx580]

LM3915 audio bargraph was one of my first completely done electronics projects ever, and it's nice to see it done "professionally" like this :D Also the most ised pattern for 10 LEDs is 2R - 3Y - 5G. Nice video, i love this vocoder series :)

[@alanhartley6934]

I have had no luck with Chinese solder. It seems to have a very dull finish and it wicks up the lead on the component. One of them had the ratios printed as 60 Pb 40 Sn, which would seem to explain this. They were advertised with the opposite ratio.

[@hughieandrolf]

I found the same poor flow issues with Jinhu 60/40 "B-1" 2% flux 0.8mm solder. It also seems to require more frequent iron tip cleaning than other solder.

[@FireballXL55]

Hi Julian I believe you could trim the edge of the RCA PCB and be able to remove the IC and have the capacitor stand vertical.

[@TheRainHarvester]

In the 80s I made my Apple][e recognize music by watching an led driven by those audio amp chips. Still only got 2nd place in the science fair. :-(

[@christopherhauck4702]

WHAT?! who won first prize? it had better not have been a f**king baking soda volcano

[@urugulu1656]

your not only sticking to the ts 100 also you seem to stick to the classic sponge method. didnt you like that brass shavings Thing?

[@JulianIlett]

I may buy another brass scrubber thing just to check if I bought a dud.

[@ElmerFuddGun]

Those caps sure are big. I haven't used those in a long time. Another style wouldn't have worked?

[@rimmersbryggeri]

MAybe put the daughter board on the under side?

[@JulianIlett]

Not possible, it would interfere with the front panel. But I could use longer pins and raise the daughter board up.

[@wreckless_-jl6uu]

How come you don’t put your PCB where we can order them too?

[@JulianIlett]

I do :)

[@wreckless_-jl6uu]

Julian Ilett where?

[@JulianIlett]

Here: easyeda.com/julian256

[@gregorythomas333]

My new MINI-TS100 and extra tips are coming in on today's post...can't wait to try it out!

[@andymouse]

Are you gonna do another revision on your board, or live with it?

[@JulianIlett]

If it doesn't fit beneath the filter boards (and I think it may not), I'll have to change the design.

[@vonries]

I've been hearing you talk about this vocoder for months now, and I must I missed the first episode. Because I have yet to hear why you want it and what you're going to do with it. Do you plan on encrypting all of your voice phone calls, or make a musical instrument? Catch us all up to date please, pretty please. I'm sorry but I'm tired of watching a drawn out project and having no idea what your goal is. My apologies, but.

[@vonries]

@@silverXnoise You can always try the 'DroneBot Workshop.' He's currently doing 2 shows a week. (I'm wouldn't be surprised if that slips at some point, as he's a "one man show.") One is any normal topic that he later relates to the second show which is building a 'real' robot. Which is an ongoing longer term project. (Or I just tune the ads out, idk) However, I don't think he does sponsors. I like them all and don't blame them a bit for making back a little bit of the money they would otherwise be spending out of pocket. Maybe it's because I don't know enough about the subject to be baffled on their design choices, or maybe I just like seeing different ways of solving a similar problem. I hope you find something you like. Good luck.

[@ElmerFuddGun]

So why did your PCBs go from $2 to $5 at 5:30? It looks like the default options and the size is less than 100x100mm. It is still cheap but just wondering what changed.

[@JulianIlett]

It may be that $2 is an introductory price - then $5 is the standard price. It's hard to tell because I think JLCPCB reset my account every time I order a PCB :)

[@ElmerFuddGun]

@@JulianIlett - Well then the website really should say $5 at that earlier point. I had assumed they just made all your PCBs and shipping free thus no need to reset anything. Just don't bill you. It all should be free for you.

[@Dust599]

@@ElmerFuddGun Its definatly $2 + shipping... Suspect he played with an option like gold plating or thicker copper.

[@ElmerFuddGun]

@@Dust599 - I thought that might be the case although I think those options are a lot more. Julian's explanation makes sense though that $2 is for your first order. Have you ordered from them, Peter? I'm hoping to have my first order placed this week.

[@alicewyan]

@@ElmerFuddGun I think it's $2 per order, but just once a day, then further orders go up to $5

[@RichardT2112]

Nice job! Try 3D printing an opaque cover for the LED, May look quite nice.

[@SudiptaMandalsuri]

please make a video on MPPT solar charge controller project. MUPPET 2 is not that useful with charging supercaps. I would really love to see MUPPET 2 charging lead acid batteries. That would be much more useful project.

[@DAVIDGREGORYKERR]

You could try the liquid flux that Tronicsfix uses.

[@NickNorton]

20:06 Component drawer with Tantalum caps and Small Signal Diodes mixed together. Urm, OK. I'm sure there's !logic to that combination.🤔

[@Hugatry]

Cool to hear feedback about that cheap solder. I just noticed my spool of solder is running out and I can't buy it anymore. Now I'm not sure if I'll switch to lead-free solder, or try some of cheap Chinese solders. Most likely no matter which way I go, I'm going to say "This isn't as good as the previous one".

[@urugulu1656]

true therefore i went with the cheapest i could possibly find which was a 50g reel of solder for like 1,5€ (.6mm Diameter)

[@steveroberts1861]

Isn't the opamp in backwards ? No orientation markings ? That's right you said you'd rather check the circuit to make sure of orientation. Seems like a waste of time and you could put a component in the wrong way and then use that as a reference making all the others wrong. Each to their own.

[@JulianIlett]

The op-amp footprint has a square pad for pin 1

[@amongstmyselves]

@@JulianIlett Check !

[@cattflap1447]

I notice on JLC they now default to 5 and you have to select 10 manually ( same price ) . I got caught by this a few weeks ago and only got 5 boards :(

[@____________________________.x]

Just noticed that myself earlier. First destroy the competition, then ramp the price back up

[@urugulu1656]

your using the lm3915 really? only know the lm3914 which does roughly the samething! whats exactly the difference and the reason you choose one over the other

[@JulianIlett]

3915 has a log scale (ideal for audio). 3914 is linear.

[@urugulu1656]

@@JulianIlett one more Thing learned

[@geronimostade8279]

I watched the full 30 minutes and you didn't even try to power it on. AHHH :D WE WANT SMOKE! Just kidding. Nice to see things going further! Cheers!

[@DogRox]

You know what would be cool for those LEDs to be mounted on the metal chassis. If you take and 3D print a bezel kind of like a mounting frame that would fit inside that slot with the rounded ends. And then that frame would have slots for each LED. That way you won't see the circuit board underneath. Just a thought anyways :-) . Still in all cool video! :-)

[@kirkb4989]

That JST kit looks nice- how is that found on eBay or Amazon (keywords?)? Did you do a postbag with those- I don't remember seeing it before but that certainly does not mean you haven't done a video about it...

[@madbstard1]

I did a quick search and found this www.ebay.ie/itm/40-Set-JST-XH-Connector-2-3-4-5Pin-2-54mm-Straight-Angle-Housing-Crimps-Terminal/232925383226?hash=item363b6f4a3a:g:EQEAAOSwWEBbmN4t

[@JulianIlett]

I'll put a link to it in the description :)

[@kirkb4989]

@@JulianIlett THANK YOU!!

[@greaser5691]

The cracking noise is the epoxy of the LEDs breaking (along with my heart :) ) because the LEDs are mounted inside the seating plane... as the leads are being bent inside the body, the body cracks. That they all work is just sheer good luck, and I'd be very surprised if they continue to work in the long term, as the hermetic seal is likely broken. The right way, if you MUST flush mount them (and you shouldn't - there should be at least 1 - 1.5mm under the body for stress relief) is to use a positioning jig to ensure they are in the correct position prior to soldering. The "leaning over caps" are nothing, again, a little strain relief prevents issues here :)

[@JulianIlett]

There's my way and the right way - I did it my way :)

[@azyfloof]

At least the chips are socketed, making it a bit easier to replace those LEDs in a few months/years when they fail from moisture ingress 😶

[@JulianIlett]

I wish they'd go a bit dimmer - I think the green LEDs are gallium nitride - they're hideously bright :(

[@greaser5691]

@@JulianIlett the wonders of constant current sources and dissimilar LED chemistries.... (and human eye response characteristics...) These devices are from the early days of LEDs, after all :)

[@christopherhauck4702]

why not use atx standard colors and if you need a beefy -12v rail add in a second voltage inverter since an atx psu already has what you need yellow=+12v red=+5v blue=-12v plus you can even have an easy soft power circuit using the existing ps-on signal line and even tie it to the pwr-good signal for if you short something out on a scp equipped psu (pwr-good is high when all is ok and ps-on is active low as well as the +5vsb for your power on circuitry/always on micro) oops pwr-good is pwr-ok and is often gray and ps-on is often green ground is black and purple is +5vsb edit: lol just google the atx-20 pin to get it all (24/28 pin ones just add extra pins for +3.3v and +12v and +5v) note: a picopsu will do the job if your device is mostly glue logic and +/-12v op-amps due to the beefy included 12v-5v-3.3v regulators and you can just hook it to your solar grid of 10-13.8v

[@followthetrawler]

I need to look at the video again but I swear you put those ICs in the wrong way around according to your silk screen

[@followthetrawler]

ah... I was distracted by the silkscreen footprint for the RCA adapter, missed the square pin 1 designator on the ICs - as you were! :)

[@sej7278]

I've got to agree re. the solder - just got some Chinese stuff and its seems blobby and grey - which probably means its mislabelled lead-free crud. Back to Rapid, the savings are cancelled out by the amount of extra time/flux/cleanup needed. I paid £2.69 for 100g of 0.7mm 2% flux 60/40, Rapid is only £4.90 (plus shipping) for the same spec; if you can setup a trade account with them!

[@JanJeronimus]

Glue two pieces of wood on the panel (that also give distance). Use two wood screws.

[@AndrewGillard]

Julian, PLEASE give lead-free solder another try! When did you last try it? Did you get the cheapest stuff or did you try something of reasonable quality? I've been using Rapid Electronics' own-brand Sn99.3/Cu0.7 lead-free solder for a while now and it's essentially the same as their 60/40 stuff - it's near enough the same price, too: £31 for 500g for lead-free vs. £26 for 500g of leaded (or £6 for 100g of lead-free, for a trial run). For a more premium option, their silver-containing Sn95.5/Ag3.9/Cu0.6 solder is also nice, but almost 3x the price at £84 for 500g or £19 for 100g (and honestly I've not noticed a difference - but both this and the cheaper lead-free stuff have worked as well for me as the leaded stuff did; there's also a £4/12g tube available). They also have some nicer lead-free solder that is apparently "Produced under license from Fuji" and has trace amounts of nickel and germanium in addition to the tin-silver-copper mix of their regular "premium" lead-free solder - so it's roughly Sn96.4/Ag3.0/Cu0.5/Ni0.06/Ge0.01 - and oddly this stuff is slightly cheaper (£80/500g), but they ONLY do 500g reels of it, and I don't want to spend £80 on a reel of solder until I know that I won't hate it! At least buy a 12g tube for £4 to prove me wrong? ;) You can even get it from their eBay store to save on postage: www.ebay.co.uk/itm/Rapid-Premium-Lead-free-Solder-with-Silver-and-Copper-Tin-Silver-Copper-Flux-/121392810585 - that eBay listing is 42p more expensive than on their own store, so that's all you're paying for postage, effectively :) (Note that Rapid's lead-free solder uses the exact same rosin flux as their 60/40 solder does - so there isn't even a valid complaint here about "the flux is more toxic"! The Material Safety Data Sheets list "Rosin 1.0~5.0%" for lead-free and "Rosin 0.5~5.0%" for leaded - i.e. no difference! ;) See for yourself: static.rapidonline.com/pdf/lead-freemsds_v1.pdf [lead-free] and static.rapidonline.com/pdf/30236s_v1.pdf [60/40]) This comment prompted by seeing this tweet recently: twitter.com/im889/status/1106658494831165440

[@FireballXL55]

Lead free never gives as good a joint as leaded it is just too brittle, I am in business because of the last 20 years of using the stuff.

[@geoffreykeane4072]

Maybe a black PCB would be a good choice in this case

[@JulianIlett]

I was just thinking the same thing - matt black would be awesome :)

[@geoffreykeane4072]

Is the front panel steel? Or aluminium? If steel you could potentially use magnets to position the assembly

[@JulianIlett]

Powder-coated aluminium - so unfortunately no magnets :)

[@Dudleymiddleton]

Just read into a bit about the vocoder, a guy called Homer Dudley from Bell labs developed it for communications way back in 1928!(Wiki) Theres me thinking that Kraftwerk ( Autobahn album) or Peter Frampton (show me the way) from 70's started it all ! And Dudley's vocoder was the first! :)

[@PracticalCat]

What I would do with that bar graph is drill two holes in the front panal the same as what you put on your pcb of course. Than get some dark tinted grey acrylic also with holes and install it behind the panal cutout. Put M3 bolts through the panal holes from the front and through the acrylic. Than used tapped spaces over the threads to hold in the acrylic window. With the remaining thread you can insert the pcb and hold it in place with nyloc nuts. Should look good with the leds behind the window:)

[@Markus0021]

Julian was concerned about how it would look from the front with the additional screws, but I think if he used black screws and hardware it would look fine.

[@PracticalCat]

Mark L yeah samm black screws will look fine if done right. Black counter sunk would look fine.

[@____________________________.x]

Epoxy two nuts to the back panel, easily hold a tiny board.

[@PracticalCat]

horse1066 good idea

[@azyfloof]

You've got that nice new flux, that'll solve the blobby solder :) Also when you're soldering LEDs like that, solder one side *only* then align the LEDs before soldering the other side

[@greaser5691]

When flush mounted, even that will cause some body cracking :(

[@jonstorey6414]

Hi. How do you manage to get them boards for $2. I'm wanting 10 boards smaller than the ones you have just been done. Each time I try I get a bill for over £60. The boards only consist of 2 555 timers and about 8 components. Most of the other parts are mounted on a eurorack pannell. Jon

[@sjm4306]

Double check minimum trace size, clearance and make sure enig (basically gold plating) is not selected. You may have inadvertently designed the board with very tight tolerances (try to keep above something like 6 mil copper width/spacing) which costs more to manufacture (it will show as an additional engineering fee). Another gotcha is making the board super thin which adds cost. And finally faster shipping greatly increases final cost (shipping can often come out to more than the price of the boards!).

[@rimmersbryggeri]

Would it be possible tu use one of those bar graphs with a decade counter to roughly indicate RPM or Frequency?

[@greaser5691]

It depends on the way you want it displayed... for voltage you'd want a linear display like the LM3914. they are a voltage response device so how you display frequency is dependent on your frequency-to-voltage conversion process, as in logarithmic vs linear (which will determine which device you select). These things will stack to 100 or more steps.

[@rimmersbryggeri]

@@greaser5691 I want to count inputs from a reluctor ring or hall effect sensor it's just a rough estimate to identify a signal. The signal will probably pass through an op amp. Its a clear way of showing signal present.

[@greaser5691]

@@rimmersbryggeri an RPM display on one of these would be a frequency-to-voltage conversion... in the old days we'd probably integrate the output of a monostable (though nowadays there are likely lots easier ways in the world of microcontrollers).

[@rimmersbryggeri]

@@greaser5691 Well a moden wheel speed sensor gives a square wave output and the older ones a sine wave what can a microt controller do more?

[@greaser5691]

@@rimmersbryggeri I think I'm missing the point of your question - or maybe I don't understand what you're trying to achieve? If you *must* use one of the LM391x devices (which give a dot or bar representation of a voltage) you need a voltage to measure, thus you need to convert frequency to voltage for an RPM indication. Unless your encoder already gives a fixed period pulse for each step you'd need a monostable and an integrator (rc network) - or a suitable microcontroller- but if you're headed down this path why not just use the micro for everything - including the bargraph?

[@MrScotttraynor]

you need some juicy lead based soldier(/BigC) ;)

[@Okurka.]

soldier

[@wreckless_-jl6uu]

Okurka both of you are dumb it’s “sodder “ 🤪

[@tamtgirl]

i'm thinking nylon stand-offs and hot glue...

[@wesleymays1931]

Or maybe something like those brass motherboard standoffs. Mmm...

[@johnjrgensen3541]

Julian, I've been following you for quite a while and love your videos. However, here, like in some of your other projects, the solution cries for a 3D printed mount. Why not get one? An Ender 3 can be had for extremely cheap. Please consider -would make the projects not only way easier but also more complete and repeatable. Please keep up the good work! Cheers ;))

[@JulianIlett]

I'd love one, but lack the space.

[@Sheevlord]

A lot of Chinese solders have botched ratios of lead to tin, hence they don't flow well. I learned this the hard way.

[@SidneyCritic]

Yeah their solders are high tin no matter what their labels says, and their fluxes do nothing. I got local solder and flux(USA), and it's like night and day compared to Ebay/Ali stuff.

[@Sheevlord]

@@SidneyCritic Well to be fair, some Chinese solders are pretty good. For example, Mechanic is a great brand (for both solder and SMD solder paste).

[@SidneyCritic]

@@Sheevlord I've tried Mech solder paste and it doesn't come out that shiny, and I've tried fluxes Kester, Yosker, Amtech, NT, etc, and they don't work at all. The flux in my local sourced solder did all the work, because you can add Ebay flux and it doesn't get any better. kzbin.info/www/bejne/aZ_YgKBuea2Ed8k

[@peerappel2012]

Hey, you should try to measure the AC voltage over the tip of your ts100 iron and ground. That will probably scare you... ;-)

[@JulianIlett]

I doubt it - it's a DC soldering iron :)

[@peerappel2012]

@@JulianIlett Okay then measure it lol. I did it and measured 95VAC. Its very weird, I don't know where that comes from. But the problem is that the iron isn't grounded. So when you don't touch any grounded parts of the iron the AC voltage will rise. It'll probably slightly depend on your psu as well but still. It was enough for me to throw it away (actually to only use it on non-sensitive things again). But probably interesting to make a video on that? :-)

[@JulianIlett]

I'm guessing you're using a mains power supply - that's probably where it's coming from. I'm using a lithium power tool battery (about 20V DC when fully charged).

[@peerappel2012]

@@JulianIlett Yeah that's right. So that indeed could make a difference. But still: my mains power adapter's (switching power supply) output should be isolated from the AC right?

[@russellhltn1396]

@@peerappel2012 The operative word here is "should". It all depends on the design. There's a chance it's got a cap or something between in and out to keep the output tied to something and not allowed to drift all over the place.

[@SidneyCritic]

Just zag-zig the poly legs, and offset them so they don't foul.

[@williamsquires3070]

For more fun, use a color-changing LED! 🤓

[@GeorgeK356]

If you send me a dimensioned sketch I'll draw up a fascia panel to take the LEDs and clip into the front panel, then 3d print it for you, Julian.

[@sirmiro2]

CA-glue solves every problem! 😁 Or make a small CAD-file and someone of us just 3d-print what you need. 🙂

[@jparky1972]

You are obviously not a "Maker" Julian. If you were. You wouldn't be looking at complicated spring solutions. HOT GLUE!

[@Edmorbus]

Julian use nail cutter

[@SomeMorganSomewhere]

Yeah, IME cheap Chinese solder from eBay just plain isn't worth it. All the stuff I've seen exhibits a complete and utter lack of flux regardless of what the label might say. You're better off buying a big roll from a reputable supplier. Considering the speed you go through it as a hobbyist it's really not that expensive, and the cost difference is worth it for the lack of frustration ;)

[@JulianIlett]

If I can still buy it :/

[@SomeMorganSomewhere]

@@JulianIlett Farnell/Element14 still sell good quality 60/40 rosin fluxed solder around £30 for a 500g roll but that should be several years supply

[@Thomas-rc9sc]

I was doing a project similar recently that uses 16 peak detectors around a PCB to detect the direction of noise with unidirectional microphones. Interesting project as always electronics.stackexchange.com/questions/429802/uni-directional-electret-microphones-and-an-arduino/429818?noredirect=1# - My project

[@jasonmonk7336]

Why not buy some flush cutters? 😊

[@TKomoski]

PCB Rev 1.2

[@ElmerFuddGun]

30 minutes and we don't get to see it working?!?! GRRRRRR... :-P

[@JulianIlett]

The video got too long and I got tired - I'm still fighting the remnants of flu :(

[@ElmerFuddGun]

@@JulianIlett - Sorry to hear about the flu. That explains the long gap from the last video. But I hope the follow up video showing it working (or not) will be soon. I was just trying to give you a hard time, buddy!