[sdiy] 4049/4069 linear mode

[Sean Ellis]

I believe the MAM Warp9 is also a clone of JH's circuit, with added VCAs for 
midi control and patch storage etc. Just FYI :-)

----- Original Message ----- 
From: "Kyle Stephens" <lightburnx at yahoo.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Sunday, May 31, 2009 10:17 PM
Subject: Re: [sdiy] 4049/4069 linear mode


>
> Tom Bugs did something along the lines of what you might be doing (is it a 
> NAND synth?), maybe get some ideas there:
>
> http://www.bugbrand.co.uk/index.php?main_page=product_info&cPath=1_14&products_id=34
>
> He uses a 4069 for distortion too, as does the JH Wasp clone:
>
> http://www.jhaible.de/tonline_stuff/hj_wasp.html
>
> I forget off the top of my head if the distortion is stock to the original 
> Wasp or not...
>
> JH and Ken Stone have identical schems for it, though Ken's is a little 
> cleaner (with my apologies to JH!):
>
> http://www.cgs.synth.net/modules/cgs49_twf.html
>
> Good luck!
>
>
> _Kyle
>
> --- On Sun, 5/31/09, Derek Holzer <derek at umatic.nl> wrote:
>
>> From: Derek Holzer <derek at umatic.nl>
>> Subject: Re: [sdiy] 4049/4069 linear mode
>> To: "Scott Nordlund" <gsn10 at hotmail.com>
>> Cc: synth-diy at dropmix.xs4all.nl
>> Date: Sunday, May 31, 2009, 3:33 AM
>> Hi everyone and thanks for the
>> feedback on this particular IC!
>>
>> Scott, you mentioned biasing the input of the gate for use
>> as an amplifier, but all the single supply circuits I see
>> using this technique such as the Anderton "Tube Fuzz" (and I
>> *think* in the Wasp filter, although I'm not sure...) do not
>> bias it at all.
>>
>> To be more specific, I'm using this in small battery
>> powered synths based on 4093 gated square wave oscillators,
>> and I'm trying to get the best use of it as both gain
>> control and overdrive. Should I worry about biasing in this
>> case? Would I get better performance out of it if I do?
>>
>> Hadn't considered driving an LED with it, was using
>> discrete transistors for that as I have a ton of 4069 rather
>> than 4049.
>>
>> best!
>> Derek
>>
>> Scott Nordlund wrote:
>> > As far as I know, the 4049 can source/sink more
>> current, so it's suitable for driving things like LEDs.
>> >
>> > Forget looking at the schematics that use the 4049 or
>> 4069, look at the datasheet (for the 4069UB, not the
>> buffered 4069B, since it's got additional stages that ruin
>> the fun). An input voltage of Vdd will turn the N
>> MOSFET on (Vgs = Vdd) and the P MOSFET off (Vgs = 0), thus
>> giving a low output voltage. Conversely, an input
>> voltage near Vss will turn the N MOSFET off (Vgs = 0) and
>> the P MOSFET on (Vgs = -Vdd), producing a high output.
>> So it works as a digital inverter. An intermediate
>> voltage will result in both MOSFETS being partially turned
>> on and operating in a more or less linear region, though
>> they weren't designed with this in mind. This isn't
>> always a good thing, as it can allow a rather high current
>> to flow from Vdd to Vss (though these chips seem to be able
>> to handle it). If you've got it biased at 1/2 Vdd, a
>> small signal superimposed on top of this will be amplified
>> and inverted. Thus it's also an amplifier, though not
>> a very good one. It uses a lot of powe
>> r!
>> > and isn't particularly linear,
>> especially for large input amplitudes, but sometimes this is
>> what you want. The very high input impedance is an
>> added bonus.
>>
>> -- ::: derek holzer ::: http://blog.myspace.com/macumbista ::: 
>> http://www.vimeo.com/macumbista :::
>> ---Oblique Strategy # 125:
>> "Only a part, not the whole"
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