Revised Parallel Universe schem (with in/out buffers)

[cantlove]

colin sed...."so an LFO with the right amount of resistance, with the right amount of resistance to 9V, too, can give you LFO control, too. Those were the real big mods as I remember. "

huhhhh? im confused! are you saying you sent a control voltage to pin 6 (vcc) of the 386... ive never considered trying that with anything though it gives me some ideas. i know schmitt inverters and some other cmos circuits respond strangely to voltage sag... could you control the tuning of a schmitt oscillator or the gain of an anderton style tube distortion with an lfo and some battery powar!? wha
!

[DreamSeller]

I havent hooked the LFO up anywhere yet, Im wondering if it goest to all 9V pins or only certain ones.

-Dream

[expanoncolin]

I would assume that you only hook up the LFO to the LM386 9V and not the input amp.

Am I Right?

-Dream

You got it.

-Colin

[expanoncolin]

So this just in (kind of)...  I have finally confirmed/decided that LM386N-3's are the onlychips that will work properly.  Each manufacturer makes a chip slightly different.  But LM386N's sound and work wonderful... the NJM's/JRC's won't  oscillate properly, -1's have less gain, -4's might sound great but I haven't tried them.

-Colin

[notickee]

Thank you, Colin.  I'll get the N3's when I go parts shopping.

I noticed on the LM386 datasheet that the polarity for the elecrolytic cap between pins 1 and 8 for Gain=200 is positive on the pin-1 side.  The corresponding electrolytic cap, C3, as shown in the PU schematics (new and old) has the "+" on the pin-8 side.  Does it work both ways?

LM386 Datasheet:  http://experimentalistsanonymous.com/di ... /LM386.pdf

[expanoncolin]

Hmm... I believe that is a misprint, but I also believe it works both ways-in fact, it works without a cap, but I think using a cap provides stability.  Let me check here...

Yes, according to my breadboard, oscilloscope, and function generator, you get the same gain using a cap in either direction or just shorting.

-Colin

[danoisefactory]

Hi,

I just found out that:
http://www.national.com/
does samples.

Anyone tried that yet? They have the LM386-N as sample.

Otherwise, small bear has them for $0,70 a piece.

greetz.

[expanoncolin]

You can get them all over for cheap-futurlec or ebay, for example.

-Colin

[DreamSeller]

Far out I've been lazy lately. Time to finally start this thing.

Rewrite of what Im doing

*3 Knob Tone Stack  - Replacing the single knob tonestack
*LFO from power source to V+ pin of LM386
*Put the starve pot back in but remove the starve switch and make it 5K (as suggested by Colin)
*secondary volume control on the "osc" footswitch so that, when oscilation is achieved it switches to a second volume pot so you can match relative output level with your "normal gain" sound.(as suggested by 'whythisreason'
*LFO reset switch (normally open between V+ and LFOs V+
*LFO switch in/out

 I assume I will need a pot the zeros out so that the starve function can be disbaled. Just out of curiosity why cant I have a starve switch with the pot "If you want gating from the starve knob, make it 5k and don't put in the switch... otherwise you won't really get any gating. LFO reset might be possible with a normally closed switch between V+ and the LFO's V+ pin. "

The only thing I can think of which I dont really know about or think is correct is that the switch may have some of its own resistance but wouldnt it be a very small amount. This is my only question.

With these modification what are the main things that would bring down the success rate. I know I should breadboard it first but I usually cant get things to work properly on the breadboard. I dont think I do it properly.

Anyhow, sorry to bring this up again.

-Dream

-Dream

[sponge]

i just breadboarded this today - it sounds immense! especially in oscillate mode!  i'll add LFO modulation to it tomorrow i think. then i'll have to find a case big enough for everything...

one question - using Colin's ''super simple dual lfo'', is it likely to make much difference whether you use a square wave or triangle wave?  if not, i'll get rid of the 1k pot all together.

[sponge]

i added the LFO so that it is switchable in starve mode.  it really adds a different sound.  the case for this is gonna be HUGE! i mean, 5 pots, 4 toggle switches and 7 jacks (thats in, out, send, rtn, sq LFO out, tri LFO out, and oscillate remote switch).  oh, and a stomp switch of course.

a question i have - when i am playing with the circuit on breadboard, in oscillate mode, the frequency knob has a good variation of sound, but sounds much better when i'm touching the casing of the pot.  despite the fact that the pot casing is not connected to the circuit (or even grounded for that matter) in any way, it acts as a body contact.  and what i want to know is: how can i get it to make that sound all the time without me touching the metal? can i use a resistor or capacitor from it to ground? the sound otherwise is okay, but its just much better when i'm touching the pot.

[expanoncolin]

i added the LFO so that it is switchable in starve mode.  it really adds a different sound.  the case for this is gonna be HUGE! i mean, 5 pots, 4 toggle switches and 7 jacks (thats in, out, send, rtn, sq LFO out, tri LFO out, and oscillate remote switch).  oh, and a stomp switch of course.

a question i have - when i am playing with the circuit on breadboard, in oscillate mode, the frequency knob has a good variation of sound, but sounds much better when i'm touching the casing of the pot.  despite the fact that the pot casing is not connected to the circuit (or even grounded for that matter) in any way, it acts as a body contact.  and what i want to know is: how can i get it to make that sound all the time without me touching the metal? can i use a resistor or capacitor from it to ground? the sound otherwise is okay, but its just much better when i'm touching the pot.

Sounds like something is shorting to the pot already.  That in general shouldn't happen, provided that your pot case is isolated from the circuit.

-Colin

[jamforthelamb]

Colin,
How hard would it be to use the input/output buffer section with a different effect ? I want to try it on a Ringmodesqe circuit that I think will work better/less noise with this tagged on.

Thanks!
JFTL

[expanoncolin]

Colin,
How hard would it be to use the input/output buffer section with a different effect ? I want to try it on a Ringmodesqe circuit that I think will work better/less noise with this tagged on.

Thanks!
JFTL

Buffer circuits in general are pretty standard.  The one here is more of an amplifier on the input, you wouldn't want that really.  Depending on the circuit, you would want to change it a little bit.  Read up here:

http://www.muzique.com/lab/buffers.htm

I'm a fan of noninverting IC buffers.

-Colin

[DreamSeller]

Man I am terrible at desinging layouts. Has anyone made one for this schem yet?

Got most of the parts and will be starting once I get the layout and etch the board. Should probably check which LM386 I have though.

-Dream