CD4049UBE "UBE Screamer" issue...

[Joe]

OT: Are they always a bit hissy?

N-channel MOSFETs always introduce noise, and therefore CMOS chips will too. The higher the gain/transistor count the more noise. One solution is to use only discrete P-channel transistors (like BS250), which have less of this problem.

[DavenPaget]

OT: Are they always a bit hissy?

N-channel MOSFETs always introduce noise, and therefore CMOS chips will too. The higher the gain/transistor count the more noise. One solution is to use only discrete P-channel transistors (like BS250), which have less of this problem.

Hissy in some circuits , but mostly unheard of in most MOS circuits .

[gregwbush]

AIIIIGHT,

I got off my ass and cut some perf!!!

the layout i'm following is that shown at RoG



I'm not done yet, but here's what i've done so far...

I've realized that not only is this my first logic 4049 build... it's my first perf-board build. I'm finding it... how you say;... interesting!

Well, i was finding it interesting... (and i'm sure this has happened to others)... but i ended up a little too sloshed and hadda put the iron down.

I'll continue tomorrow and POST results

(just previewing the post... to verify...i am in fact using solder, not tar, whatever the picture may depict)

cheers,
gregwbush
(jeeeez they really are bad photos, thought i was an expert. anyway when i'm done youz'll see  )

[gregwbush]

Sweeet

It works


i socketed the diodes and resistorX


So... what have i learned...

Component layout can be crucial in a high gain circuit!
Perfboard is quite cool
RunOffGroove know their $h!t
Oscillation by closely arranged parts doesn't necessarily cause an audible squeal or fundamental unwanted "tone"... it can be supersonic (above the audio spectrum) and cause all kinds of weird, instabilities and misbehavior of a circuit

Ummm

4049ube is a great package full of mosfet goodness, but must be utilized with some thought involved
UbeScreamer (even unshielded, as mine is, currently) is a nice circuit! I'm liking it for it's crunch, nasal tone AND it's ability to drive BSIAB2 into a nice lead tone. When i put it in a box it'll be even better

BTW, even unshielded... i'm not hearing "hiss" what so ever into clean channel. There is noise when boosting another overdrive. I dunno, define hiss

cheers,
gregwbush
thanks for everyone's input! I'll do a video and or sound clip and post (at some stage)

[B Tremblay]

I'm really glad that it is working well for you.  Thanks for sharing your build report!

[gregwbush]

I'm really glad that it is working well for you.  Thanks for sharing your build report!

You're welcome, i've learned a lot.

By all means feel free to use my pictures Mr RoG... i'll shove it on the scanner tomorrow if i can and do the top and bottom and you can use those on your website if ya want...

[WGTP]

As always I could be wrong, but raising the clipping Threshold on any of these types of devices, increases the output, but not the noise.  Try 4 silicons or 2 LED's for increased output/less distortion with less noise. 

[DavenPaget]

As always I could be wrong, but raising the clipping Threshold on any of these types of devices, increases the output, but not the noise.  Try 4 silicons or 2 LED's for increased output/less distortion with less noise. 

2 red 3mm led's .
Usually more gain = more noise , when you raise the clipping threshold you might be raising the noise threshold i believe , but that's just me  and i might be wrong

[DavenPaget]

Trem , what do you say about that feedback loop diode or a signal-to-ground diode ?

[WGTP]

Unless things are drastically wrong, the noise should be way below the clipping threshold.  Changing the diodes doesn't change the gain, but increases the output.  IIRC 

[gregwbush]

As always I could be wrong, but raising the clipping Threshold on any of these types of devices, increases the output, but not the noise.  Try 4 silicons or 2 LED's for increased output/less distortion with less noise. 

Now there's an idea WGTP
I'll try that, and maybe adjust rx to compensate levels
Not looking for maximum distortion, far from it

2 red 3mm led's .
Usually more gain = more noise , when you raise the clipping threshold you might be raising the noise threshold i believe , but that's just me  and i might be wrong

Nah nah nah nah nah... same gain, less clipping... no, wait, fuuaark... i'm confused now

You bloody poofters. I've got LED's, i'll do it now and see what happens

[gregwbush]

Ok i put 3mm red leds in...

Gotta turn the gain knob up to achieve clipping

It doesn't sound right. RoG schematic diodes sound better

There's less noise i think... but it sounds wrong

And now i gotta insert the diodes again... fiddly

cheers,
(shouldn't be drinking at 11am) gregwbush