Adapting an EM clone for use with MN3102

[Big Monk]

Currently on a binge of available info on the subject of BBD chips and their associated clock chips.

If I understand the crux of the issue with respect to MN series dedicated clock chips, it's that they struggle to provide the correct clock frequencies due to the high clock capacitance of the MN series BBD chips, such as the MN3007.

I'm in the process of putting a circuit together using the rough form of the MBP Current Lover as a template, but with frequency response tweaks that get it in line with the Past FX Elastic Mattress.

In doing so I'm looking for efficiencies in component choices:

1.) Subbing out the extra opamp stages by using a BC549C based output gain stage to combat lack of unity gain and subbing in modern UA741 and the OPA2134 used by the Mattress. This lets me eliminate the TL072 and LM324.

2.) My main question is centered around the use of the MN3102 along with the CD4049UBE. It seems I could eliminate the CD4013 and its extra and unused stage. I'm not looking for a complete and quick answer, but rather, some guidance on the implementation that I could dig into.

I'm also interested in the role the LM311 plays in the circuit.

Flangers are a new subject for me with respect to design and I'd gladly take any advice of what I should look into from a design standpoint. My goal is something sonically equivalent to the Mattress but with some more deliberate and efficient component choices so I don't have to contend with using additional opamp stages as buffers or having one half of the CD4013 sitting unused.

[Big Monk]

So I realized that since this was a late night post, and since I was pretty much half asleep, I offered no supporting documentation!

Here is the Current Lover as drawn in Diptrace:



Here is my rough draft attempt at simplifying some things:

[Kevin Mitchell]

I can touch on some of this.

You should know that;
-On the clock chip the OX pins are taps for a "inverter oscillator" circuit. Without the supporting circuitry it will not oscillate but instead, act as a non-inverting buffer.
-In the first schematic the flipflop will effectively half the frequency that's driving it.

I believe you'll have to complete the inverting oscillator circuit and see about halfling the pulse from the comparator without modifying the LFO.

[Big Monk]

I can touch on some of this.

You should know that;
-On the clock chip the OX pins are taps for a "inverter oscillator" circuit. Without the supporting circuitry it will not oscillate but instead, act as a non-inverting buffer.
-In the first schematic the flipflop will effectively half the frequency that's driving it.

I believe you'll have to complete the inverting oscillator circuit and see about halfling the pulse from the comparator without modifying the LFO.

I thought the LM311 and corresponding circuitry was the VCO circuit? Forgive my naivete on the subject. Flangers, though a favorite of mine for PLAYING, are new to me in the sense of uilding/designing.

[Kevin Mitchell]

You're right, here the LFO lends itself to the comparator where the feedback on the negative input creates a moving target which results in a continuous modulated pulse (or that's how I see it).

Typically with these dedicated clock chips (3101, 3102) we have our supporting parts to complete the inverting oscillator, to where we then modulate it for warbly goodness.

But my point was, with the flipflop coming off the comparator we know that whatever the frequency was is now at 50%. You need to complete the OX pins so that it acts as a flipflop and not a simple buffer (2 inverters in series and nothing else).

[Kevin Mitchell]

This is from the MN3101 datasheet - which I think the MN3102 and V3102 sheets lack IIRC


This is what I mean by inverting oscillator.
It reminds me of a recent endeavor of mine, where I used a CD4049 to create 3 independent flipflops to actuate an tri-channel analog switch IC - an alternative to using 1 1/2 CD4013 chips.

[Kevin Mitchell]

Just noticing;
You're connecting VGG from the clock. You should leave it floating here since it's supplied externally.
Remember that a 3102 was not designed to drive a 3007. While both chips require 2/3 the supply voltage, consider the difference in polarities between the two technologies (NMOS & PMOS)
*The clock's VGG is simply a complimentary reference voltage of 2/3 the supply*

[Big Monk]

Just noticing;
You're connecting VGG from the clock. You should leave it floating here since it's supplied externally.
Remember that a 3102 was not designed to drive a 3007. While both chips require 2/3 the supply voltage, consider the difference in polarities between the two technologies (NMOS & PMOS)
*The clock's VGG is simply a complimentary reference voltage of 2/3 the supply*

Good catch, the 3101 is probably the one to use in this application.

[Big Monk]

This is from the MN3101 datasheet - which I think the MN3102 and V3102 sheets lack IIRC


This is what I mean by inverting oscillator.
It reminds me of a recent endeavor of mine, where I used a CD4049 to create 3 independent flipflops to actuate an tri-channel analog switch IC - an alternative to using 1 1/2 CD4013 chips.

Please keep in mind that my questions are coming from trying to understand and are not by their nature "questioning"....


To be clear: This is a non-standard implementation AND I'm not well versed in BBD chips, clock circuits, etc.

So is it that the CD4013 of the original V2-V5 and V6 EM and the V1-V2 DEM forms a part of the oscillator circuits?

I'll admit I cribbed the current implementation from a different flanger circuit that did not use the other OX pins.

[Kevin Mitchell]

Good catch, the 3101 is probably the one to use in this application.

More appropriate - especially if you want to use the complimentary VGG. But to use that you'll have to omit the external reference and reconfigure the bias trim to the new VGG signal.

So is it that the CD4013 of the original V2-V5 and V6 EM and the V1-V2 DEM forms a part of the oscillator circuits?

Yes, as a clock divider. For every two cycles at it's input the output cycles once - due to the nature of a latching flipflop.

I'll admit I cribbed the current implementation from a different flanger circuit that did not use the other OX pins.

What circuit?

[ElectricDruid]

So is it that the CD4013 of the original V2-V5 and V6 EM and the V1-V2 DEM forms a part of the oscillator circuits?

Not exactly part of the oscillator. The BBD needs a biphase clock (both a positive and a negative version of the waveform) and the 4013 is one way to provide that, since it has both Q and !Q outputs. The fact is also halves the frequency is not especially helpful in this application, since it means we need to run the clock at an even higher frequency to get the delay times we need.

With flangers, the problems are:
1) Getting a modulated clock/VCO of sufficient frequency
2) Getting a biphase output
3) Getting sufficient current drive to overcome the BBD clock pin capacitance at the sort of frequencies we're talking about.