Thursday, January 31, 2013

Catching up.... Updated Ring Modulator

I'm way behind.  I've built all all kinds of modules since my last blog post.  With each module I build,  I begin to understand how little I really know about electronics.  I'm learning a lot and I can now recognize reoccurring themes--especially with Op Amps--but I don't guarantee any designs I post on here.  I'm an amateur just trying to figure stuff out.....

So lets start with my updated ring modulator.  The ring modulator itself is a passive circuit but there's a huge volume loss after the signals(input and carrier) pass through the transformers.  The previous design used two LM741's to boost the signal before the transformer Diode ring. The circuit design itself wasn't ideal, at high gain it caused high frequency oscillations and all it really did was overdrive the signal before the transformers.

I rebuilt the module with a single LM741 after the ring modulator circuit as a simple recovery amplifier, to account for the volume loss.
This is a sketch up of the schematic.  Since I bought the Ringmodulator kit from Synthrotek , I really only had to focus on the amplifier aspect of the circuit.  The two potentiometers control the incoming signal volume and arn't really necessary.



It was a simple enough circuit that I went ahead and  sketched the circuit freehand on a piece of copper clad pcb.


The circuit seems to work well, with little or no wave distortion.  I've seen some modules which add a 555 oscillator circuit, but I'm not personally a huge fan of the 555 or using the Ring Modulator with a constant frequency, so I kept mine simple and use external oscillator signals.

 

in the video I'm using two synthesizers.com oscillators with the ring modulator,  I'm controlling the gate with a simple arduino random midi generator sketch I made.  One oscillator is fed pitch voltage from the arduino and the other oscillator is fed pitch voltage from an ADSR.  then my camera ran out of batteries..... ENJOY!


4 comments:

  1. Hello. I'd really like to build this ring mod circuit with the pots for the carrier and input. I've attempted to copy the schematic at the top on my breadboard but I got none of the ring mod effect, just sound coming in and out with the pots (sort of) controlling the volume. I'm a tad confused, I assume the input and carrier are the tip from the jack sockets, then are you just grounding the sleeve? This may seem like a foolish question but I'm new to this.

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  2. yeah, the sleeve should be connected to ground. are you using the syntrotek kit also? can you hear both signals when the pots are turned all the way up?

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  3. No I'm not using the kit. Originally I copied the schematic of the syntrotek kit out onto my breadboard which all worked fine, but when I integrated the extra bits you've added for volume control the actual ring modulation didn't take place.

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    1. I made the schematic based on a circuit I put together on my breadboard, not the other way around. because I was modifying my older design, the synthrotek kit was already assembled on their pcb board. It sounds to me like something isn't connected correctly inside the ring modulator part of the circuit, and when I was writing, i just pulled a picture of a ring modulator schematic off the web because I didn't see one on the Synthrotek website. My module works and I'm fairly certain this is how it's wired. so if it was me, I would assemble the kit on their pcb and work backwards from there.

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