Zombie build report (few posts down)

[strungout]

Oy. Argh.

Well, I thought I'd build myself some time delay effects. I bought an NM3007, MC14049BCP (cross matched by the store guy to the CD4049) and a CD4046BE. I was going to breadboard John Hollis' ultra flanger and then his zombie chorus.

So, ultra flanger, messed up the wiring, too tired, smelled wierd, burned my index on the 4049, probly dead. Oh well. The 3007 and 4046 weren't hot at all, so I'm figuring they're ok. Maybe they're not. Gonna go buy more soon.

Now I been on the zombie chorus all day, using two TL072 as the op-amps, and can't make it work. I did make some progress after looking up all I could find on the forum and putting up three different bias networks ( ), now the signal gets through to the output, but the 3007 only outputs hum. I don't think the lfo is working...the voltage at pin 9 of the 4046 doesn't change at all, and I can't hear anything with my audio probe (I should be able to here it, right?).

So, all this talk to basically ask if someone could give me some voltage reading from a working unit?

BTW anyone find it wierd that I paid 0.99$ for the MN3007? That's what's written on it, along with the number 11. I thought those were like 10$ US...

Anyway.

Ciao.

[strungout]

A little update.

Like I said, I fed a separate bias to the 3007 input, using a 10k trim with a 10uF cap to ground from the wiper and through a 100k resistor (suggested by M. Hammer in some thread). I used a 0.1uF cap to decouple the previous stage.

So, I noticed a "pop" sound as I turned the trim. I carefully dialed it in and now the 3007 does output the guitar signal, along with the hum, and turning the controls of the lfo does change the sound a bit, but it's all very distorted, faint jet-like sounding. Any ideas?

[Mark Hammer]

Oy. Argh.

Well, I thought I'd build myself some time delay effects. I bought an NM3007, MC14049BCP (cross matched by the store guy to the CD4049) and a CD4046BE. I was going to breadboard John Hollis' ultra flanger and then his zombie chorus.

So, ultra flanger, messed up the wiring, too tired, smelled wierd, burned my index on the 4049, probly dead. Oh well. The 3007 and 4046 weren't hot at all, so I'm figuring they're ok. Maybe they're not. Gonna go buy more soon.

Now I been on the zombie chorus all day, using two TL072 as the op-amps, and can't make it work. I did make some progress after looking up all I could find on the forum and putting up three different bias networks ( ), now the signal gets through to the output, but the 3007 only outputs hum. I don't think the lfo is working...the voltage at pin 9 of the 4046 doesn't change at all, and I can't hear anything with my audio probe (I should be able to here it, right?).

So, all this talk to basically ask if someone could give me some voltage reading from a working unit?

BTW anyone find it wierd that I paid 0.99$ for the MN3007? That's what's written on it, along with the number 11. I thought those were like 10$ US...
quote]

Not surprised that you were able to find an MN3007 for 0.99$.  That's not to say anyone charging you more is gouging you.  Rather, there will be instances where someone figures "Eh, I've had these things sitting in the bin for decades.  Price them to move, Morty." and other instances where someone else figures "They don't make these any more.  Anyone who can find a consumer for them can probably ask a pretty decent price.  No reason why we shouldn't get in on the action.  Charge 'em five bucks apiece, and let *them* figure out how to make a profit on the resale."  It's also the case that wholesale distributors who sell to retailers may have bought them in smaller OR larger lots originally.  FWIW, I bought some MN3207's last year for $1.49@ from a local place.  Certainly surprised me.

The hum suggests your problems are stemming from some sort of wiring error, rather than a burnt component.  My best advice is to plug your guitar or CD player in, and trace the signal at each possible "station", from input jack onwards, with the AC voltage setting on your meter.

[strungout]

Hehehe, that's what i was thinking today when I left the electronics shop..."hmm, maybe they're just tryin to get rid of it. I need to come back and get some more.."

Ok, well, I'll rebuild the thing and be extra maniacal about the wiring :p.

Thnx.

[strungout]

So, some progress.

I rebuild the whole thing per RG schematic. Now I have guitar, hum AND distortion at the ouput of the BBD AND the LFO works.

I tried different schematics since I was having problems, and noticed differences between them. Tomboy's schematic shows the inverting pin of the integrator to Vb. John Hollis's and RG's show the non-inverting to Vb. Changing that made the LFO work. The rest is as I described in my first post. The other differences is that John Hollis's schematic shows pin 16 and 14 tied together, RG's does not. Does this matter? RG's schem specifies that pin 8 of the BBD connects to +9V. The schematic shows it is, but through a 47k resistor and is also connected to pin 7. Why the specification?

Should I tie any other pins to ground that are not mentioned on any of the schematics?

I'll go use the search again.

Ciao.

[strungout]

Well, I gave it another shot after the ultraflanger worked. Turns out the problem was that pin 14 of the 4046 needs to connect to pin 16. Ditto. RG's schem shows it on the pcb layout, and even has a small box to tell you about it, but somehow I didn't read it and just followed the schematic.

Also turns out I don't like the effect  :?  Sounds like dry/wet tremolo.

EDIT: I stand corrected. It WAS too choppy at lower settings, but a 10uF cap across the bias line to ground of the seperate LFO I put in cured that. The bigger value it is, the most it seems to kill the effect.