Consolidating Richard Holmes's Stereo Kosmo Design

DIY STUFF
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KicadStereoRevisionPg1
KicadStereoRevisionPg11920Ă—1484 169 KB

KicadStereoRevisionPg2
KicadStereoRevisionPg21920Ă—1358 167 KB

Hello! Glad to be apart of the community! Any help at all would be appreciated.
I started with this project because i wanted to be able to plug my headphones into my synth and hear sound in both ears god dangit. While i believe there may have been easier ways of getting what i wanted, I really wanted to get hands on experience with KiCad and the PCB designing process. However, after getting the PCB fabricated and populating the boards it became apparent i may have made some assumptions i shouldn’t have or simply don’t know as much as i need to. I would also have liked to share the gerber file but am not entirely sure how to best do that.
On pg2 of the Schematic i listed some of my assumptions but will list here as well:

  • Sliding VB was changed to a A100k knob VB

  • I didn’t know how to get The 2 gang Variable resistors
    to have a proper symbol with pins 4,5,6. instead of 1,2,3 a second time. If the Gangs are in front(closer to you) pin 4 would be in front of pin 1 far left. .
    RV5, RV6, RV7, RV8, RV9 are all these 2 gang VBs.
    The 2 gang variable resistor i was using: RK09L12D0A1W

  • All Grounds are connected to the ground pour which seemed fine in this case based on the research i did.

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If you didn’t discover some issues on your first substantial PCB you’d be a highly unusual person!

The dual gang pot symbols are Device:R_Potentiometer_Dual or Device:R_Potentiometer_Dual. The first gives you a single symbol:

image

while the second has two units so you can put the two gangs in different places in the schematic:

image
image732Ă—295 5.43 KB

Pot pin numbers are a mess. The footprint Potentiometer_THT:Potentiometer_Alps_RK09L_Double_Vertical corresponding to the pot you used looks like this:

image

This is viewed from above the pot, not behind it, so the pin numbering looks like this:
image

The footprint Potentiometer_THT:Potentiometer_Alpha_RD902F-40-00D_Dual_Vertical for the Alpha equivalent looks like this:

image

As you can see the two use different numbering conventions. It doesn’t matter, though, because the two gangs are the same and which is used for which part of the circuit doesn’t matter. Either way pins 1 and 4 are counterclockwise. What’s really bad is that for instance Potentiometer_THT:Potentiometer_Piher_PC-16_Dual_Horizontal is

image
image719Ă—345 11.9 KB

where pins 1 and 4 are clockwise. I always use pins 1 and 4 counterclockwise in my designs.

If I understand what you’re saying you are assuming the opposite convention, pins 1 and 4 clockwise. You’d be in good company but you’d need to use a footprint that reflects that.

However, your schematic has the pots hooked up in a way that assumes pins 1 and 4 are counterclockwise. If they are taken to be clockwise then they’d behave “backwards”.

In my schematic there are different ground symbols because there were three different circuit boards connected with pin headers. Their grounds were connected to one another. Indeed they not only can but must all be connected.

One more minor point having to do with terminology: “Variable resistor” refers to a 2-terminal device which acts as a single resistor whose value varies, and it’s generally accomplished by tying an end terminal of a pot to the wiper. In this circuit the pots are used not as “variable resistors” but as “attenuators”, acting as two resistors whose individual values vary but whose sum is constant, implemented by using all 3 pot terminals individually.

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Wow thank you for all the help and clarification on terminology! Genuinely pumped to get to troubleshooting on this and see if my translation to Gerber had any other issues. :+1:

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