Flanger Electric Mistress: schematic comparison

[Elijah-Baley]

Hey guys, a new challange here.
I'm ready to build a flanger, but no stripboards this time.
Now, I'm comparing two schematics of the Electric Mistress.

These are the Building Doc.
Current Lover by MBP: http://www.madbeanpedals.com/projects/CurrentLover/CurrentLover_2015.pdf
Op-Electronics PCB: http://www.op-electronics.com/it/index.php?controller=attachment&id_attachment=110

I noticed some differences, in some value or in some portion of the circuit, but of course I don't know what those mean.
Here's the schematic with the difference parts highlighted.





I got:
- Current Lover uses the MN3007 chip while the OP-Electronics uses V3207 (or MN3207). This works equally, but is even slightly different, so the it needs some extra parts.
- Current Lover had change the value of the Clock Trimmer from 100k to 10k: «which will make calibration easier.»
- Current Lover had change the Output Section (using the Op-Amp instead a Transistor Stage), and the volume potentiometer is now just a trimmer.

I guess there's some difference in the power section and in the Send/Return bypassing I didn't get. And those difference value or missing parts, that I definetly didn't  get.

Who can tell me something about this effect?

Thanks!

[Slowpoke101]

Have a look at this thread

https://www.diystompboxes.com/smfforum/index.php?topic=91981.0

It is a very interesting wealth of info. I've built two of these units and I modified one to accept an MN3007 BBD device (because I did not have an 3207 at the time).
The component values in the filters do make a difference but my main issue was output levels. The other difficulty was setting the clock frequency (well, not for me as my work requires a full RF workshop).
Have a look and you will find things that will help. Dr Alx has really done some great research and experiments with this device. Very helpful. A big thank you is also in order to Thomeeque for originally posting this.
It really does sound like an Electric Mistress. The diagrams that you posted are very similar and should be fine to use.

[Elijah-Baley]

Thanks for the link! I have to read all the thread.

Meanwhile, I'm looking the schematic in the pdf (http://thmq.mysteria.cz/em3207/build/EM3207_v1.1_Build_Instructions.pdf). Well, even this look a bit different in several parts .
I got some tricks about some caps value that adjust the bright/dark/color/chorusing in the effect.

I'm pretty sure that one of the schematic I posted will make sound the pedal good enough. I'm going to buy the "Electric Flanger", the second schematic.

[...]
The component values in the filters do make a difference but my main issue was output levels. The other difficulty was setting the clock frequency.
[...]

What filters you mean? Those caps I mentioned early? What is the volume issue?
About the clock adjustment MadBeanPedal changed the trimmer value to adjust it easily. It could be useful?

[Slowpoke101]

The filters that I referred to are basically made up by the caps (and resistors) that you are thinking of. They do change how the flanger sounds. Both circuits use suitable component values to get fairly close to an Electric Mistress's (EM) tone but you can experiment with different values.

Output level would not be an issue with either of these circuits as they both have amplifiers on the output (my builds didn't). One being an OP Amp and the other being a transistor set up as an LPB1 circuit. I had some difficulties with the two devices that I constructed when I changed some of the filter components to sound even closer to an EM's tone. I just built an LPB1 onto the outputs of my units.

The OP-Electronics flanger would be a good one to build as it uses the 3207 BBD chip - which is not hard to obtain. The MN3007 can be very hard to obtain. The reason for the differences in the BBD power supply schemes is that the MN3007 has some odd power requirements whereas the 3207 has some odd biasing requirements. But the 3207 has a maximum applied voltage specification of 10 volts, hence the zener regulated supply.

The effects loop on the Mad Bean circuit would be an option should you want to apply an effect to the non delayed audio. No idea what effect you may want to try in there but the option is available. If it was not to be used you would just use a linking cable between the sockets.

So either board would be fine to use but the 3207 BBD is easier to obtain so go for the OP-Electronics board and build it. You will not be disappointed. You may wish to buy a frequency meter to help set the clock. Something that can read up to 2MHz would be fine and very cheap. Some of the LCD transistor testers do have this feature.