LM358 exponential VCO help

[justjools]

Hi, I am a Euro enthusiast and have just started to build some simple DIY circuits. I have been trying to do this LM358 VCO and I have done the main part of the VCO circuit but don't understand how the separate parts fit together if you can help me.

https://www.allaboutcircuits.com/projects/diy-synth-series-vco/

1) I understand the VCC with two resistors on the left connect to the 8 leg VCC of the middle chip. But I don't understand the right VCC; there are two VCC connections here and it doesn't say which is connected to which. Do you think they are connected in series like this:

2) There are two other parts to the circuit here. I could just do this as a separate circuit but the BOM lists only 4 LM358 chips. With this as a separate circuit that would be 8 so I think this circuit is actually overlayed with the other circuit and uses the other 1/2 of the 4 opamps. If you look in the first circuit it's using 6,5,7 legs and in the second it's using 1,2,3,4,8. Which says to me these are the same circuit but have been separated out to illustrate different functions. The first is the exponential circuit and the second is the VCO. If you have a look at the final picture it has only 4 opamps, and I don't get how these two schematics are combined. Do you think you just overlay them?
Pic of what I've done so far following the VCO schematic at the end.

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[PHOBoS]

1) Vcc is just a label used for the positive supply so they all are connected together (in parallel).
The same goes for Vee which is the negative supply.

2) Yes, the LM358 is a dual opamp so there are indeed 4 used in total and you are correct about the pin labels.


I noticed you posted it twice to add another picture which you could do with the edit function, or if you have
more than 5 by making a new post (reply). So I removed your first post but for some reason this seemed to
have removed some of the pictures you attached in this post. Or maybe it's something else and just a coincidence
Sorry about that I don't know how that happened .

[justjools]

That's a real help. I now know what VCC and VEE mean

I think I'm going to have to start again though as I was following the VCO schematic only and need to put both schematic connections to the same opamps on one board. You would've thought they could provide a schematic with all parts of the circuit together.

If you have any good suggestions for easy euro circuits to try out I'd be very grateful.

Thanks

P.S. The site is very slow and unresponsive and why it posted twice; I hit the button again thinking it had stopped when it was still loading.

[gdavis]

Schematics are often split into multiple pages. It makes it easier to read, it can get very cluttered putting everything on one page. The labels are key as PHOBoS explained. Basically every net with the same label is connected together.

Yes, the site can be quite slow sometimes. Just be patient and never click submit twice If I'm not sure if something got posted, I'll copy what I typed then go back to the original thread and hit refresh. If my post doesn't show up then I'll click reply again and paste what I copied before and re-submit. But usually just being patient it will eventually go.

[Grumble]

Vcc = Collector supply voltage, Vee = Emitter supply, Vdd = Drain supply, Vss = source supply.

The voltages can be negative or positive depending on the the device and the circuit configuration. In circuits using NPN transistors Vcc is generally positive but if you were using PNP transistors then Vcc would be negative. In a circuit with a mixture of PNP and NPN devices Vcc take the polarity of the predominant technology used (generally it would be positive).
(source: https://forum.allaboutcircuits.com/threads/what-is-vcc-vss-vdd-vee.28782/)

[justjools]

That's all really helpful guys. Thanks