Gentlemen, don your deerstalkers - the game is afoot!

Started by moid, July 14, 2021, 08:14:59 PM

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rutabaga bob

#60
Okay!  Just got done testing with cap @ pin 9 disconnected.  Now have lots of gritty wind noise!  Yahoo!  Jim, should I just go ahead and leave it 'cap-less'?  Didn't notice any warble-y end of decay like some of the video, but then I didn't sit and fool with it a whole lot in its rigged, spaghetti-wired state.  Many thanks!
Life is just a series of obstacles preventing you from taking a nap...

"I can't resist a filter" - Kipper

anotherjim

Try a smaller cap. The wind-down you might hear is the DC volts on the cap draining off making the pitch fall.

rutabaga bob

#62
Not sure exactly what you mean by 'wind-down'.  The pitch isn't falling.  And which discharging cap are you referring to?  The .1uF at pin 9 is disconnected.  Sorry to sound obtuse.

EDIT: did some more listening, changing control settings.  The gritty noise and fadeout is all I've got - no warble.  This is with NO cap at pin 9.  Will put in some smaller-value cap and try again, I guess.  Hope to get 'that' sound soon!
Life is just a series of obstacles preventing you from taking a nap...

"I can't resist a filter" - Kipper

rutabaga bob

Today: different small cap values...same velcro fuzz with good sustain.  Bridged pins 3 & 4 to no effect.     ???
Life is just a series of obstacles preventing you from taking a nap...

"I can't resist a filter" - Kipper


anotherjim

Put the scheme up again.
The cap that should affect the modulation is the one on pin9 together with the Depth pot setting.
Hmmmm... you do know this kind of thing only works properly with single notes? And then best with a neck pickup and the tone turned to 0. Whack it with a chord and it will always be messy garbage.
The Depth pot (clue in its name) should smooth and reduce the modulation signal.

If you link pin 3 & 4 it probably won't shut up. You would change the depth pot from pin2 to pin13 to make that happen. You could add a mode for that with a DPDT switch.

I've just noticed pin12 is grounded. Usually, that's a resistor (not less than 10k) or nothing. Hmmmm... Try removing that ground.



rutabaga bob

Ungrounding pin 12 will require some work in the rerouting of the ground on the pin across from it, and the ground coming from the 386.
Have changed that cap to three different values.  Still just the gritty effect...no warble.

Will post my version of Moid's layout in the near future.
Life is just a series of obstacles preventing you from taking a nap...

"I can't resist a filter" - Kipper

anotherjim

If the chip is in a socket, pull it out, bend pin12 outward and put it back in. Tada!

rutabaga bob

Mr. Jim...I believe that's the answer hidden under the hot glue.  Took your Q & D test advice and weirdness came forth!  Definitely don't ground pin 12.  Reconnected to the .1uF cap shown at pin 9 and it works fine; no need to use a smaller value cap.

I know this wasn't Moid's goal when he put up the post; I didn't mean to hijack your thread.

Thanks to you all!
Larry
Life is just a series of obstacles preventing you from taking a nap...

"I can't resist a filter" - Kipper

anotherjim

Hoorah! And it only took 4 pages! Should have done it in 2. A grounded pin on the right-hand side of the chip just looked odd when I saw it again. There's usually no ground on that side with the  4046 chip.

duck_arse

" I will say no more "

rutabaga bob

#71
Don't know anything about embedding sound clips.  Have enough trouble with pix.  Might email you a couple, doubting Duck.

Edit:
https://i.postimg.cc/W4CJHYxX/BAC1-C4-A9-7-A59-43-EA-8-ACE-0-ACD727-F0-D61.gif

Revised a couple of times along the way, this one tweaked to avoid pin 12.  Basic layout from Moid.
Life is just a series of obstacles preventing you from taking a nap...

"I can't resist a filter" - Kipper

rutabaga bob

What ho!  Well folks...when last we met, the effect was functioning nicely.  I put it back in its box and lent it to a friend to try out.  He...tried to do so.  All it does now is whistle.  Frequency changes with pitch control, intensity with blend control.  When this is occurring, no notes from the instrument go through.  On bypass, all is fine.  Removed/taken off of enclosure (an electrical junction box) the problem remains.  Am left wondering if the chip went south, or what.  Any ideas? 
Life is just a series of obstacles preventing you from taking a nap...

"I can't resist a filter" - Kipper

anotherjim

It's not in your hand at the moment? I'd ask (diplomatically) if they plugged in & out cables the right way around!

rutabaga bob

I got it back and tested it myself this afternoon.  No go.
Life is just a series of obstacles preventing you from taking a nap...

"I can't resist a filter" - Kipper

anotherjim

Chip pin voltages will help, otherwise, it could be anything.

rutabaga bob

#76
Okay.  Bear in mind some pins change due to pot connections & positions thereof.
1: 0
2: 9.05
3: .73
4: 4.53
5: 0
6: .826
7: .821
8: 0

9: 8.06
10: 7.6
11: 6.88
12: 6.95 (n/c)
13: 0
14: 8.69
15: 0
16: 9.66
Life is just a series of obstacles preventing you from taking a nap...

"I can't resist a filter" - Kipper

anotherjim

I don't like pin14 voltage - too high. Looks like the output of the 386 is stuck near 9v. Check its 0v connections are good and the rest of it's pin voltages. Or it could be short between the track from pin14 to D2 and the + end of C2.

rutabaga bob

386 voltages.  Pins 1 and 8 not bridged.  This original build doesn't have the diode and C2 near each other.

1: .590
2: 0
3: .393
4: 0

5: 9.02
6: 9.66
7: 4.25
8: .136
Life is just a series of obstacles preventing you from taking a nap...

"I can't resist a filter" - Kipper

anotherjim

Trouble at the LM386. Pin5 is its output should be biased around 4.5v not near 9v. If the 386 is in a socket, take it out and check voltages on the socket pins. Only pin6 should be 9v.