Hey there guys,
I've been gathering some schematics for a ring modulator build. I've settled for an AD633 multiplier, and will also try the 4xOTA oscillator that Guillaume suggested.
I've also started to think about putting a LPF after the modulated signal - yes, this is becoming increasingly similar to Randy's Revenge - and there are some VCF schematics on the LM13700 datasheet. Have you guys experimented with these? I mean, I'm already going to use 2xLM13700 for the oscillator, might as well use 3 and have a filter too.
Fairfield Circuitry - Randy's Revenge
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DWBH
- Cap Cooler
Following this thread, and because I'm building the said LM13700 sine wave oscillator mentioned previously, has anyone got a correct spice model for it? I've been running some simulations with Ltspice with a voltage-to-current source very similar to this one (http://www.birthofasynth.com/Thomas_Hen ... t_0001.pdf; I'm using +-9v and potentiometer is +9v to ground; R21 is 1M) feeding the Iabc pin. However I'm getting disparate results with the two models. In one, it works, and reacts from 10uA to 800uA on Q2 collector; in the other one, it only oscillates from 400uA upwards on Q2 collector. I still haven't tried it on the breadboard, and I don't have an oscilloscope to test it, so I have to rely on simulators.
One other thing, regarding square waves. This may sound stupid. Multiplying two signals (guitar*carrier), if I want on-off type of modulation (like a tremolo), the square wave needs to be 0-Vpeak, right? I mean, it needs to have a DC offset of Vpeak/2. Otherwise, if it doesn't, on the negative half of the wave, it will just invert the phase of the guitar signal, right?
One other thing, regarding square waves. This may sound stupid. Multiplying two signals (guitar*carrier), if I want on-off type of modulation (like a tremolo), the square wave needs to be 0-Vpeak, right? I mean, it needs to have a DC offset of Vpeak/2. Otherwise, if it doesn't, on the negative half of the wave, it will just invert the phase of the guitar signal, right?
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DWBH
- Cap Cooler
Beautifull board. Here I was thinking the filter was also LM13700-based. Guess not.
Vactrol is used for the filter, I guess. It has three 'legs' on the LDR side, so probably it's controlling R1 and R2 here?
Vactrol is used for the filter, I guess. It has three 'legs' on the LDR side, so probably it's controlling R1 and R2 here?
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Ice-9
- Transistor Tuner
Information
And why would it not be LM13700 based, I can see 2 of those on the pcbDWBH wrote:Beautifull board. Here I was thinking the filter was also LM13700-based. Guess not.
Vactrol is used for the filter, I guess. It has three 'legs' on the LDR side, so probably it's controlling R1 and R2 here?
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It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !
No silicon heaven ? preposterous ! Where would all the calculators go ?
No silicon heaven ? preposterous ! Where would all the calculators go ?