Messing with a CD4047

[StephenGiles]

Some flangers use a 4047 (pins 10 & 11) for BBD clocks configured for voltage control, often using a 4007. There is another output at pin 13 - oscillator output, the pulse width of which can apparently be varied by the same flanger LFO, and used in conjuction with a 4016 to produce switched resistors.

My question is could this additional output be "normalised" by additional circuitry to produce a clocking signal at a determined fixed frequency, to be used with a second BBD having a fixed delay?

 

[StephenGiles]

Let's see what gems of brilliance spring forth this evening!

 

[PRR]

I don't understand the question. If you want a fixed frequency, get another oscillator. CMOS oscillators are cheap.

 

[StephenGiles]

That is a fairly obnoxious answer PRR :grin: :grin: . I want to convert the pin 13 output from a voltage controlled 4047 (frrom LFO) in a flanger to a clock signal with a static frequency to drive a second BBD with a static delay in order to get through zero flanging without the problems of using 2 separate clocks. Not easy I would think.

 

[gyraf]

If you have a LFO-controlled 4047, and I guess you're using out-of-phase-pins Q and not-Q 10/11 for driving a BBD, then pin13 won't have a fixed frequency, just 2x the frequency of pins10/11 - whatever that is set to be by the current state of the LFO.

For through-zero flanging, why not just repeat the whole circuit, and control with inverted-phase LFO - that should give you max. bang-for-the-buck.

And I agree with PRR - cmos oscillators are not really that hard or expensive to build.. :razz:

Jakob E.

 

[StephenGiles]

I agree, easiest of the lot, but I was trying to avoid the heterodining problems associated with twin clocks.(bad spelling but I'm hungry!!) Still, it does provide the means to have a few phase shift stages in the flanger feedback for instance, using 4016 gates to switch resistors, controlled by the PWM output of the 4047 at pin 13 - could be interesting. I have an ADA Flanger built on veroboard with plenty of space (uses a 4047) so I might just try that out. Swept phase shift stages in the normally dry signal of a flanger might sound interesting as well.

Hope I didn't sound rude PRR, I had a bad night!

 

[StephenGiles]

http://www.tasteundtechnik.de/bilder/adafinalph1.jpg
I forgot to include the link to the ADA finalphase which started me thinking about all this.

 

[StephenGiles]

Funny, I thought the ADA Final Phase was quite a rare one!

 

[gyraf]

Isn't it?

I've not seen the schemo before - but then again, it's more like a stompbox-sorta-thingy..

:razz:

Jakob E.

 

[StephenGiles]

Yes it is a stompbox but I thought the PWM was interesting - and never been seen before using a 4047/4007 combination more associated with flangers.