This Week on the Breadboard: The 'lectric Mama Flanger

Chuck D. Bones said:
Fixed it! Had to rearrange the power distribution and grounding and increase the filtering on the BBD output a little. Here's how it looks now. The 5V reg is hiding behind a capacitor to the left of the LFO/CLK chip. Compare the parts count to the all-analog LFO & clock gen. The RATE, DEPTH & MANUAL controls have a huge range. Only two trimmers req'd. The RATE, DEPTH & MANUAL are voltage-controlled, which means they could be hooked up to an expression pedal or other control source. I'm calling this 99% done. I want to spend some more time playing it and reviewing the circuit design. I'm considering the merit of adding an output buffer. This circuit is layout-sensitive since the 4KNOBFLANGE chip puts digital noise on the power and ground rails.

View attachment 18668

View attachment 18669
Click to expand...

Boneyard Edition!!!!

EDIT: I've got all the major pieces for this one so I'm hoping you do decide to make a board of it.
 
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Output Buffer: who wants one?

This circuit needs an output buffer if you're driving a low-impedance load like a Fuzz Face or Range Master.

A simple output buffer requires four more parts: two R's, 1 C and an NPN transistor (or JFET).
 
Chuck D. Bones said:
Output Buffer: who wants one?

This circuit needs an output buffer if you're driving a low-impedance load like a Fuzz Face or Range Master.

A simple output buffer requires four more parts: two R's, 1 C and an NPN transistor (or JFET).
Click to expand...

Can't hurt! Just picked up the ED chip. I already had the 3207s I bought for my upcoming Cepheid build.
 
If you do end up doing a board for this, would you consider making the Blend an external control?
 
OK, not completely fixed. There is still a slight tick in the LFO/Clock chip near one end of the sweep. It's an artifact of the chip code. I must reluctantly remove the 4KNOBFLANGE chip from the design because once you hear the tick, you can't un-hear it. Standby for further developments.

Regarding the external BLEND control, what exactly do you want it to do? Bear in mind The 50/50 mix provides the deepest flanger tone.
a) Sweep from 100% dry to 100% wet. The wet end would be pure vibrato with no characteristic flanger tone. We'd want a pot with a center detent so we can easily find the 50/50 mix.
b) Sweep from 100% dry to 50% wet.
c) Sweep from 50% wet to 100% wet.
 
Chuck D. Bones said:
OK, not completely fixed. There is still a slight tick in the LFO/Clock chip near one end of the sweep. It's an artifact of the chip code. I must reluctantly remove the 4KNOBFLANGE chip from the design because once you hear the tick, you can't un-hear it. Standby for further developments.

Regarding the external BLEND control, what exactly do you want it to do? Bear in mind The 50/50 mix provides the deepest flanger tone.
a) Sweep from 100% dry to 100% wet. The wet end would be pure vibrato with no characteristic flanger tone. We'd want a pot with a center detent so we can easily find the 50/50 mix.
b) Sweep from 100% dry to 50% wet.
c) Sweep from 50% wet to 100% wet.
Click to expand...

Dang! That's a shame about the ED chip. It was foolish of me to order one without the design complete.

As far as the sweep, I think b) captures what I have in my head.
 
I agree, it's disappointing.
You might want to breadboard the circuit and give it a listen. If you avoid the top-end of the sweep range, there's no tick. Unfortunately for me, that's the end of the range I prefer to use. Plan B is to try using the STOMPLFO chip and the original clock osc. The advantage of the STOMPLFO chip is we have access to 8 different LFO waveforms, so that could be fun. Plan C is to revert to the all-analog design.
 
Chuck D. Bones said:
I agree, it's disappointing.
You might want to breadboard the circuit and give it a listen. If you avoid the top-end of the sweep range, there's no tick. Unfortunately for me, that's the end of the range I prefer to use. Plan B is to try using the STOMPLFO chip and the original clock osc. The advantage of the STOMPLFO chip is we have access to 8 different LFO waveforms, so that could be fun. Plan C is to revert to the all-analog design.
Click to expand...

Either way, I'm pumped. Plan C would not bother me at all as I just purchased the same chips for the Cepheid and would only need to grab a few more things for the LFO. Ordering the STOMPLFO is not a deal breaker either after finding out shipping direct from ED is super reasonable.

Keep us in the loop. This is very exciting.
 
At long last, I think I'm done massaging this beast. Presenting The 6-knob Flanger.

SPEED - DEPTH - MANUAL - COLOUR - BLEND - WAVEFORM

Per Big Monk's request, I installed a BLEND control and it comes in handy with some of the more "out there" settings.
The LFO is realized in the Electric Druid STOMPLFO chip. ED provide the HEX file for free to DIYers. I burned the code into a PIC 16F18313. That chip sells for a little over a buck. The schematic is on two sheets to make it more readable. The audio path is on sheet one. The power supply, LFO and clock gen are on sheet two. I annotated the voltages I measured on my breadboard. I designed it with all B100K pots. Most of the eight waveforms available from the STOMPLFO chip are useful. The sine and triangle produce the traditional flanger sweep. The two random waveforms are fun. There is a hyperbolic "sweep" waveform that is of no use with this clock VCO because the VCO has a hyperbolic response to control voltage. If you only wanted two or three waveforms, that could be achieved with a few resistors and a SPDT toggle switch in place of the WAVEFORM pot. The STOMPLFO chip also has a Tap Tempo input that I did not use. It basically overrides the SPEED control. Any of the four control pots on the STOMPLFO chip could be replaced with an expression pedal or an external 0 to 5V control voltage. The SPEED, DEPTH and MANUAL controls have a huge range. I typically set SPEED below noon and DEPTH below 10:00.

'lectric Mama v3.2 page 1.png

'lectric Mama v3.2 page 2.png
 
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The proximity of the capacitors to the IC note...is that to reduce inductance between them? If no, perhaps a brief explanation please?
 
I increased C23 to 560pF which moves the clock VCO range lower and the Electric Mistress tones are definitely there! Set the WAVEFORM to Triangle, MANUAL to zero, BLEND to max and you're there. Put a fuzz in front of it for the full jet-engine effect. So far, I've tried a Servo FF and Chuck's FZ-1 and they both sound bitchen. With other control settings, we can get a nice chorus or some spaced-out atonal synth effects.

Controls L-R: WAVEFORM - SPEED - DEPTH - MANUAL - COLOUR - BLEND

Chips L-R (top row) STOMPLFO (U6), clock VCO (U5), clock driver (U4), BBD (U3), 5V reg (U7).
(bottom row) mixer and Vref buffer (U2), preamp and pre-emphasis (U1).

Colour & blend trimmers are huddled under the COLOUR control.

The top power bus is Vdd (+5V).
Blue row below that is digital ground.
The middle red/blue pairs are Vcc & analog ground (2 rows of each)
Bottom red row is Vref.
Bottom blue row not used.

The notes about cap placement are to keep the digital noise originating in U6 from getting into the analog circuitry and to keep U6's control inputs from being upset by any noise pickup.

'lectric Mama breadboard v3.2 02.jpg
 
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