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Topics - mjg

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16
I had a few hours with the rest of the family out of the house today, so decided to build a spring reverb tank recovery on breadboard.  It was going pretty well, but after a while I could smell burning.  Not good.

I figured it was the wacky 15v circuit I'd built, so tried to work out what I'd done wrong.  None of the parts seemed hot.  Burning smell getting worse.

After 5 or 10 minutes of wondering what was causing the smell, I thought I'd check outside.  Huh.  Burning smell outside the house as well.  Maybe the neighbours have lit their fire? 

Went back inside, and kept breadboarding.  Smell is definitely stronger inside, and getting worse.  After another 5 minutes, I thought I'd check the rest of the house.

Oh.  Right.

I'd started cooking dinner.  Left some beans boiling on the stove about an hour ago. 

Grey smoke billowing out of the saucepan, smoke all through the kitchen and the rest of the house, down to about eye level. 

My lessons for the day:

- don't get distracted by the breadboard
- use a kitchen timer
- get a new smoke detector, because the one we have didn't make a peep, and it was swimming in smoke. 


17
Open Discussion / Pickups for a hurdy gurdy?
« on: June 20, 2019, 04:33:37 AM »
A mate of mine is building a hurdy gurdy... which is really hard to type without autocorrect getting upset.

He has asked me how he would install pickups to connect to a small amp. 

I'm thinking it will be something like a semi-acoustic?  Small microphone or piezo or whatever.  The instrument seems to have different sounds from different sets of strings, so probably needs pickups in multiple locations. 

Anyway, anyone have experience with this kind of instrument?   :o

18
Build Reports / Phaser build
« on: May 08, 2019, 04:06:07 AM »
This is based on the Mu-Tron Phasor II circuit, with a few more options to vary the sound.  I've put in two rotary switches, which let you vary the number of stages in the phaser from 3 to 8, and change the tone capacitors of the first four stages.  Also a 'slow' switch to really drop the speed of the phasing, and a relay bypass. 

For something different on the enclosure, I've used the drill press with a depth stop, and drilled a pattern using different drill bit sizes. It was a bit nerve racking with the larger bits, as I thought it might punch through the metal completely, but it worked out pretty nicely in the end.

Stamped lettering, which got a bit hairy near the edges, where I didn't support the enclosure underneath properly.  It ended up bending then tearing the aluminium, and I had to hammer it back into shape.  Whoops.  Doesn't show with a bit of a sand, thankfully.











19
Open Discussion / New (old) (free!) amp day
« on: April 24, 2019, 06:05:49 AM »
Got this for free today - my partner saw it on a local 'free stuff' website.  A 'Princeton', but not a Fender amp.  It's a Prince PG-100SA - solid state 30w amp.

As far as I can tell, it would have been produced in the 1970s by the Prince Tsushinkogyo company. They renamed in 1980 to Arion, and stopped making amps in the mid 80s. 

It's got a bit of character, and could do with some cosmetic work, but it still fires up and worked fine.



It has a small spring reverb built in, as well as tremolo. 

I'll need to replace the back panel, fix the carry handle, fix the power light, and maybe change the scratchy volume pot. One of the input jacks seems to have been glued in place at some point, and wobbles a fair bit, so I'll replace that too. I'll also have to find some knobs for it, once I work out what the original would have looked like.








20
Build Reports / Solar Flare
« on: November 05, 2018, 02:00:43 AM »
This is a 'Solar Flare' board from Nucleon FX.  Thanks again to Rockhorst for the build of the year prize last year.  It's taken me this long to get through them all!

The circuit is based on the Keeley Fuzz Head.  I've used an AC128K for the germanium transistor, and for the diodes I went with 1n4148, 1n270, and a cheeky D9K hanging off the side of the board. 



The enclosure was an old tobacco tin.  The previous owner died from lung cancer.  Don't smoke, kids.  Public service announcement done.   Anyway, this is a much better use for the tin.





It sounds... fuzzy.  I'm not sure that I'm a fuzz connoisseur, so probably not the best person to judge this one. :)

I used a waterslide print to do the labels on the top... but after 60 seconds under the water, the decal still didn't budge.  At this point I realised that I'd grabbed the vinyl sticker paper, not the decal paper.  Don't put sticker paper under water.  It doesn't work. 

21
Open Discussion / guitar input -> USB-C recommendations
« on: October 23, 2018, 03:32:46 PM »
My 6 year old laptop has started to have issues, so I'm going to replace it. :( 

The old laptop had an audio line-in socket.  Worked great for occasional recording of the guitar. 

New laptops all seem to be USB-C.  It's the way of the future apparently. 

I'm looking for recommendations for a USB-C to line-in or guitar in converter thing.  Doesn't have to be super high professional quality.  Something that works with Garage Band on the Mac if possible (but I imagine pretty much anything that presents an audio source via USB will work?)

22
Build Reports / Saturn V + Redstone
« on: October 19, 2018, 02:53:45 AM »
This is two more boards from Nucleon FX, combined into the one enclosure. First up, a Saturn V distortion, then second, a Redstone boost and equaliser. The distortion is really good, it makes you feel like a rock god, even if you can only strum a few chords like me.   :P

These boards were from Rockhorst as part of last years BOTY prize.  Thanks Rockhorst!   They work well together.  It also works well with the bass guitar.



Given that both boards had rockety type names, I went with a rocket type theme for some of the text.

This is my first attempt at stamping the letters into the metal. It turned out OK!

For the letter stamping, I used my sledge hammer as an anvil, and then stuck some angle metal on the top of the enclosure using masking tape, to act as a guide. Then used a normal hammer to belt the letters in. The anvil idea worked OK, but wasn't as effective on the lettering closest to the edge, where it wasn't quite supporting the top of the enclosure. 

I've used some model paints to colour the lettering, and sanded it off to 240 grit.



I think I may have hit 'peak silver knob' on this one.  Not sure that I like that much aluminium, so I might swap to black metal knobs later if I don't get used to it. 





Did I realise after stamping all the letters and doing all the drilling, that I'd put the wording for 'In' and 'Out' on the wrong sides? You betcha. I had to cut the lettering away with the rotary tool, then redo it on opposite sides. *sigh*  No one will ever notice I'm sure...




23
Build Reports / A couple of builds
« on: October 10, 2018, 04:27:52 PM »
Two builds that I've finished up - both boards from Nucleon FX. 

First one is the Celeritas compressor, based on the Diamond compressor.  I've used the CoolAudio VTL5C3 vactrol in this build, and it seems to work fine with this circuit.  I also ended up putting in a small board with a voltage doubler, to make the effect run at 18 volts, to remove a bit of the distortion when the compression first kicks in.

Drilling the enclosure on this one turned into an exercise in stupidity. I wasn't wearing gloves, and was holding the enclosure while drilling. The drill bit stuck, which turned the enclosure into a spinning blade of death... and took a chunk out of my finger. It also ripped a bit out of the hole it was drilling, so one of the side jacks is on an angle.





Next one is the Solstice drive.  I like the sound from this one.  Lots of options to sculpt the tone. 

I couldn't decide whether to bias the input stage as a buffer, or to give a bit more of a boost, so I ended up putting in an extra switch to change the bias on the fly. Probably didn't need it in the end, but I do like options.

I was happy with the waterslide decal on this one - I got the graphics to line up pretty well with the knobs and switches.  I drilled the holes first, then stuck the enclosure on the scanner, which gave me a template for doing the graphics. 

I then managed to drop a sharp knife on it when cutting out the holes after applying the decal.  It left a bit of a mark near the In jack.  :(

Covered the decal with some yellow acrylic, which looks really odd in the photos but much better IRL. 










24
Open Discussion / 9mm pot drought?
« on: September 10, 2018, 03:42:22 AM »
Just trying to buy all the 9mm pots I need on Tayda... and they are out of the sizes I need.  Restock is listed as end of November.  Two and a half months???  Outrageous. 

Of course, they have hundreds of thousands in stock of the values I don't want. 

Gah, first world problems!    ::)

25
Build Reports / Yet-to-be-named wah pedal
« on: July 15, 2018, 12:52:21 AM »
This is a wah pedal that I've been procrastinating on for at least six months now.  I started by reading the RG Keen article, and played around with all the components until I settle on a 4 way switch for the centre frequency, and I've added a pot to control the gain/distortion of Q1.  Used a yellow Fasel inductor. 

Board by Elecrow, and I added a 3PDT and rotary mini board as well, to make the build easier.  I named the PCB 'Yowie' as that seems to be the equivalent of 'Bigfoot' in this part of the world. 





Inside wiring is pretty minimal, but I did need to run ground wires to the backs of the pots and to the enclosure itself.  Apparently the paint that I used was too good an insulator.



For the finish, I have matched it to the guitar that I built last year. I'm using car spray paint (rattle cans), in a red and black, with clear coat over the top.





Then sanding the clear coat down with 600, 800, 1200, 1500, 2000, 4000, 6000, 8000 and 12000 grit paper and pads. After that, a rub with some car scratch remover.  I didn't spend as much time sanding as I did with the guitar, so the finish isn't completely scratch free.  But it does the job. 






26
Build Reports / Liquid Eternity chorus
« on: June 24, 2018, 12:47:46 AM »
This is a Liquid Eternity chorus from https://www.nucleonfx.com/, based on the Arion SCH-1 from the 80s. It's a nice sounding chorus, and works well with guitar and bass from my testing.

This PCB came as a prize from the Build of the Year competition in 2017, so thanks go to Rutger at Nucleon from providing the prize (along with a few more PCBs I'm still working on!)

There are a lot of components on this board, and it was very tightly packed. Good soldering practice.  I added a momentary switch in place of R13, to allow for a momentary removal of the dry signal - it gives a really swirly vibe type sound when pressed.

Only 'issue' I had with the build was that I wanted to use a clear blue LED, but it didn't seem to play nicely with the optical bypass system on the board. I'll revisit that at a later date (or, most likely, just put up with the red defuse LED).

I also need to get a source of metal washers. The white plastic ones don't look fantastic with the rest of this build.  (Anyone know where to buy the right size metal washers, in Australia, let me know.  I've tried the hardware store but the M12 washers seem slightly too small.)

The guts:



For the enclosure, something new for me.  My partner got bought me a voucher for a metal engraving course for my recent birthday (where she finds these ideas I don't know), so I took this enclosure along to the 2nd day of the course.  Turns out I was the only person at the course, so I had two days of one on one instruction, and we got to work on whatever I wanted.  My efforts are pretty amateur, the stuff that the instructor does is amazing. 

A few photos from the engraving course:





The text is done with a tiny chisel by hand, rocking the chisel side to side as I wrote the letters. The other cuts have been done by a hand held, air powered chisel, to cut the pattern into the aluminium. Then used an air powered stipple thing to put tiny little dots into the pattern.

I finished it off with 400 grit sand paper.  That's taken off some of the pattern, so I needed to carve deeper in some spots obviously.  I'll be looking into getting some of the chisels to use on future builds.  The whole air powered setup costs thousands apparently, so won't be getting that any time soon.   :-\









27
General Questions / Wah inductor too tall...?
« on: May 24, 2018, 04:41:20 PM »
I'm building my first wah pedal.  I've got a yellow Fasel inductor to stick in, but I've now realised that it is too tall to fit in the enclosure space.

So far my thinking is: 

- I could rotate my PCB 180 degrees, as there is a bit more vertical space if I have the inductor at the top end of the board.  But then I'd have all the connections for the jacks etc at the wrong end.

- I could try to bend the pins on the inductor by 90 degrees so I could lie it down... I'm a bit worried that I'll damage the inductor doing that though.

- I could just lie it down and solder on some extra leads coming up from the PCB to join it all up. 

So, how do these things normally get installed? 

I've been looking at pictures on the internets and there are a few where people have just bent the inductor pins... so maybe I just need to man up and give that a try. 


28
Build Reports / Chopped OC-2 clone
« on: March 13, 2018, 12:28:22 AM »
This one is a chopped OC-2 clone - on Diablochris's PCB "The Low Down".   It does octave down. 

I wasn't really happy with the 'clean' signal path in this schematic, as it ended up clipping quite badly at the first op-amp. So I ended up removing the volume pots, hard wired it to have no clean signal, and then made a small blend circuit to mix between a proper clean and the octave effect.  Also added optical bypass on the vero board. 

The octave down works pretty well, on guitar and bass.  It tends to crap out on the lowest string of the bass.  But that's OK. 

I thought I'd measured everything three times, but when I put the switching and blend circuit into the box, it was about 2mm too high, and the lid didn't close.  Dammit. So I pulled that apart, reversed the switch and a few components, and got it to fit.

Graphics are a blended octopus with cat. I dunno, seemed appropriate. And I think this is the most expensive knob I've put on a pedal - it was about $7. Given that there was only one knob, I figured I could splurge on it, while still maintaining the pedal to knob cost ratio. :-)








29
Open Discussion / My pedal blog got hacked :-(
« on: March 11, 2018, 02:59:28 AM »
I sat down tonight to write up a few build reports, and found that my pedal blog had been hacked. 

It's some stupid javascript that has replaced all of the WordPress default javascript with nasties, and it's also gone through all of the other Wordpress sites that I have on the same domain and infected them too. 

So.  No build reports tonight.   :'(

I've deleted all my sites so that they can't infect anyone else.  I left the images so hopefully my old build reports still show up with images in their threads. 

I've managed to save the text of all my blog posts, when I'm feeling up to it I'll try create a clean install and import what I can.  Not really feeling motivated to do that right now. 

And I was having such a good weekend - building a new desk for pedal building, and some shelves to house all the pedals. 

Stupid internet.



30
General Questions / Wah pots - recommendations?
« on: January 23, 2018, 01:39:35 AM »
I'm looking at building a Wah pedal some time soon, and I'm interested in opinions about the pot to use.

Is it worth getting the Dunlop Hot Potz II, or will I not really notice a difference between that and something cheaper? 

There are cheaper 'generic' ones, but I'm not sure if they are just a normal linear pot with a gear stuck on, it is hard to tell. 



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