Years ago I bought my wife a copy of Korg DS-10. I always knew it was buried away somewhere but only just recently unearthed it. An amazing thing happened - I actually understand interface now! Funny how it only took a few months of building a DIY synth to finally figure it out. Its quite fun to noodle around with now and I have the feeling it will be a handy little tool to have in the arsenal.
This had me wondering if there were some way to interface it with my modular. Low and behold I found this! It looks to be an incredibly simple build - comparatively speaking.
The biggest hurdle I can see is the power situation. The original circuit seems to run on a 9v battery and I see requirements for 4.5/-4.5v on the schematics which makes some sense. I dug around and found this - but I’m not sure it is exactly what I need. Would I be converting to 9v? Or 4.5?
Or I could just bite the bullet and instead of making a module out of it, I could just use the battery.
On first look I’m kind of confused by some of that schematic, like what are J4 and J5 for? Why are there 47R resistors between the rails and “ground”? Maybe it becomes obvious if you stare at it long enough.
Anyway, if it were my job, I think I’d look into converting the circuit to run on ±12V, probably replacing the TLV2370 with a TL071; I’m not sure why they used that but I don’t think you’d need to in a ±12V version. Otherwise I think you’d have to do something like use +5V and -5V regulators for your rails (not 9V because then you’d have to use a fake ground, and the ground for this module would be different from the ground in the rest of your system, ugh).
A huge proportion of modern electronics is Chinese. Perhaps it’s about time people stopped referring to electronics as Chinese garbage. We’re probably all relying on a lot of “garbage Chinese” gear to communicate about the clever things we’re making with “garbage Chinese” boards. This stuff isn’t made in Pittsburgh or Sheffield or Essen. Those days are gone. It’s made in lots of countries, and some of the best is made in China.
The more I look at this the less I understand it. What are those 6.8V Zeners doing in there? It almost looks like they’re using them to rectify ±4.5V signals, but that would be nuts, especially since if they don’t want negative signals, why do they bother to fake a split supply in the first place?
And I can’t figure out R11, it looks like a pull up resistor but why would you pull up the output of a comparator?
That’s not the right way to wire an unused comparator, is it?
I did figure out J4 and J5, they’re battery clip and DC input. And overall it seems to make some sort of sense, I think they’re rectifying the signal, integrating it, and putting it into a comparator. Just the details I’m baffled by.
Somewhat related question…say you are working on a circuit that accepts 0-5v cv like an arduino. How can you protect it from overvoltage from typical CVs
Ok, that’s a lot simpler solution that I’d have imagined…well off to go read about schottkys cause I’m not wrapping my head around how that works
The main thing with Schottkys is they have a lower forward voltage (Vf). The anode can’t be more than Vf above the cathode, so if the one diode’s anode is connected to ground and the other’s cathode to +5V then the junction can’t go more than Vf outside 0 to 5V. The resistor is to limit current.
Pretty sure a 2N3055 will cost you more than a standard voltage regulator, so that’s just silly. Just get a 7805 and run the output through a diode, and you end up near 4.5 V (use a shottky diode if you want just above 4.5 V). Or get an LM317 and a trimpot.
