Meatball Builders' Lounge

[80k]

Hello,

I recently started building the Meatball thanks to Moosapotamus' schematic and layout (great job with that by the way, Charlie!)...

just wanted to start a new thread for Meatball builders.  I don't think anyone has verified the layout/schematic right?  This would be a good place to share any problems/ideas/mods, etc...

Anyone have any thoughts on what to use for an optocoupler?  I ended up using some rectangular LED's i had lying around, as well as these photoresisitors I had (Mouser P/N 338-54C348).  These are rated at 500K dark, and between 3k and 20k at full light.

so far, everything looks good between the layout and schematic...  I noticed there was no hole specified for the V+ to the board... but there's a via just below pin 4 of the quad opamp where the V+ can go, unless i'm mistaken...

Cool thanks... i'd love to hear other people's experience with this!  i hope to get most of it done this week, although i gotta get a few caps, the dual opamp, and the 1k, 5k, and 10k pots.

[80k]

bump

[moosapotamus]

I noticed there was no hole specified for the V+ to the board... but there's a via just below pin 4 of the quad opamp where the V+ can go, unless i'm mistaken...

That's the spot.
I'll be interested to now how it turns out.
Thanks
~ Charlie

[80k]

I noticed there was no hole specified for the V+ to the board... but there's a via just below pin 4 of the quad opamp where the V+ can go, unless i'm mistaken...

That's the spot.
I'll be interested to now how it turns out.
Thanks
~ Charlie

yep, i hope i can finish it soon... i'll be sure to give you a report, and sounclips if it works right! (or if it at least makes noise  )

i'm probably going to try a 4558 instead of the 1458 dual since i have a bunch of them lying around.  other than that, a few caps at the surplus store, and some pots from Mouser, and i'll be set to go.

thanks

[petemoore]

Im a littel behind on this subject...
 what is a Meatball, and where is the schematic??

[80k]

Im a littel behind on this subject...
 what is a Meatball, and where is the schematic??

http://www.diystompboxes.com/sboxforum/viewtopic.php?t=195&highlight=meatball

The Meatball is a Lovetone Filter effect.  never heard one though, but it looks really cool!

[psst]

So how did it work finally, 80k?
And did yo use the VTL5C3?
BTW, Moosapotamus, did you use VTL5C3s too?

[moosapotamus]

That was my plan.
But, I guess I'm easily distracted.
Been working on some other stuff. :mrgreen:

~ Charlie

[80k]

hey,

just finished the board and have all the hardware for the rest of the pedal (except for the box).

i ended making my own optocouplers with photoresistors and LED's, hopefully it works out okay.

i'll let you all know how it turns out.  i probably won't wire the stuff up until next weekend, unless i find some time tomorrow evening

[80k]

well i put the meatball together this morning!

hmm... well it is making sounds, and it is filter-y..  the 3 position toggle doesn't seem to do anything...

also, when i engage the Sweep (so that the LED's come on), it gets a drop in volume, and the filter-y almost goes away.

the mode and range works well.

the decay doesn't seem to do much.  according to the schematic... only one pin on the decay (VR3) pot goes the circuit board.  the other 2 pins are connected to each other and nothing else... (i didn't add the Pedal1 and Pedal2 so the VR3 is not connected to any other jacks).

is this correct?

cool, i'd love to hear how others are doing on this, thanks!

[tomtom]

Good sounding ?

Tomtom

[80k]

Good sounding ?

Tomtom

eh... not yet... things aren't working 100% though!

i'm looking at the schematic... and it really seems Decay should go to something when Pedal 1 is NOT engaged.  doesn't make sense to have a pot there like that.

[moosapotamus]

80K -
I populated and wired a board. But, that's about as far as I got. I did try plugging everything into my bread board, once, to try to check it out. But, I couldn't get anything out of it. Man, there's a ton 'o' wires on that thing. I just assumed I had made some wiring mistakes and left it at that. How many times have you double-checked all your connections?

By the 3-position toggle, do you mean the Sweep control (3PDT toggle switch)? I'm not sure why you would get a volume drop from the Sweep control (sorry)... Unless it could be related to the LDR/LED combo you selected.

As for the Decay control, I'm pretty positive that that IS the way it's wired in the original. But, after glancing at Mark Hammer's article on the technology of auto-wahs, I'm wondering if the wiper of the Decay pot shouldn't be tied to ground through a closed-circuit jack.

Keep in mind, Decay is very interactive with the Attack control. For example, you might not hear any differences in Decay with long attack time settings, because the decay will finish before the attack is done.

~ Charlie

[80k]

hi Charlie,

cool thanks, yea i definitely am getting some cool sounds.  actually the sweep isn't really giving me a volume drop on all the settings... it all depends.  it'll probably be easier when i get it in a box, cuz it's hard to tweak with the pots all over the place, haha...

yea, i tried putting the sweeper to ground on the decay... nothing happened... i'll have to play around with it some more this week.. i'll let you know how it progresses!

[RickL]

I finished one of these  a short time ago using home brew opto's. I can get the filter to sweep by moving my hand between the LDR's and a light source but I can't get the envelope detector section to work (the LED's don't light up and fade with picking).

I wonder if there shouldn't be some sort of bias voltage going to the op amps in the envelope detector section? Maybe it's there and I'm just not understanding the schematic. If I get a chance this weekend I'll try juryrigging a Vb and sending it to where I think it should go. I'll report back on my results unless someone posts first to tell me that it works as posted and I've just screwed up somehow.

[Paul Perry (Frostwave)]

RickL, I think you might be right about there being some problem with the envelope detector. It looks like nothing I've ever seen in that regard! Even if the bias was run to 1/2 vcc, it still isn't anything like the textbook ideal diode. (though, I believe it would rectify).

[80k]

yep, mine is not envelope detecting either.

i willl try to look into it more this weekend if i get a chance.  i need to get a box for it too, so it'll be easier to tweak the knobs!

i'll report back... and anyone else who's putting one together or has any input on it, please continue to share your results and ideas! thanks!

[RickL]

First, VR3 (Decay) does indeed have to go to ground. The wiper goes to ground instead of to the tip of the Ped. 1 jack. I wired the jack to parallel VR3, junction of R8 and VR3 to the tip.

More important U2A has to be biased. I disconnected R5 from ground and connected it to a variable bias consisting of a 50k trim pot hooked between +9V and ground with a 47 µF cap from the wiper to ground (R5 to the wiper). It wants a little less than 1/2 V+ to work best to my ears.

Tweak it by ear but the right area seems to be where the external LED just turns off (or just turns on depending on the position of the up/down switch). If you want one more knob you might want to make this an external pot since slight changes in the bias seem to produce different envelope responses. If you do this you might want to use a smaller value pot with resistors on each end to make more of the pot travel usable.

I found the colour pot mostly useless except in the upper 1/8th or so of its travel.

This one's got lot's of possibilies. I'll report again when I've had a chance to play with it a bit more.

[petemoore]

Anything with more than two knobs 'offboard, and I consider the ckt a good candidate for the cardboard with holes in it.
 I take a piece of faily sturdy cardboard ..bout 14x12'' and punch holes around both [three?] sides....over backing so I dont bend and crease it.
 this keeps the wires from snagging and pulling, I do the same same with the input output connex..sticking the plug through the cardboard, and wrapping  the [input/output] tips with ~1.5''' of exposed wire [from ckt in/out] and clamping the grounds on to the sleeves...that way I can turn the knobs without disurbing everything, tweekbug the ckt with no byswitch or jacks, and be able to stack it on another set [just like it] or 'shelve' it without having wires get caught.
 Then wheniff it gets a box ... just push the pots loose... and continue !!

[80k]

First, VR3 (Decay) does indeed have to go to ground. The wiper goes to ground instead of to the tip of the Ped. 1 jack. I wired the jack to parallel VR3, junction of R8 and VR3 to the tip.

thanks for the info!

so according to the schematic, VR3's pin 3 and the wiper are connected together.  So did you have it set so that both pins 2 and 3 of VR3 are connected to ground?  or did you have the wiper go to ground, and pin 3 go elsewhere?  the reason i ask, is that i'm setting it out WITHOUT the expression jack.

hopefully i can get this working this week! thanks for your help!