WickedBlade

Hey guys, I'm still a newb here, and for my project (PBEX+a) I would like to use a CMOS switcher, but I have almost no clue as to what and how. I know that I'll have only 5V power supply to work with, so the CD4053 seems out (if I understood the datasheets correctly). I've found another candidate, that would be the HC4053. This one seems to be working with lower voltages, so that might be a winner. But I don't know how to check that and how to design that part of the circuit. Specifically: the HC4053 wants a 'negative input voltage' (Vee), I'm wondering if feeding this with ground would work, possibly by supplying a fake, positive ground to pin GND. I was thinking of feeding 0/2.5/5V respectively to Vee/GND/Vcc. But I don't know if the switching inputs would still be happy with being wired to DOUT. Of course I've tried to do some research on the forum, but couldn't come with good keywords. If anybody could give me some clue or, even better, a schematics, that would be much appreciated. The datasheet can be found here: http://www.st.com/stonline/books/pdf/docs/7731.pdf

Mmmh, I'm not convinced, but I'm definitely not the expert, here. I guess I'll have to find either a 2A PSU or buy two 1A PSU. Bugger! Physically speaking, I was thinking of having the various signal jacks on the left side of the unit, while the MBHP modules (and related LCD and 7-segment digits) would be to the right. I'm not quite sure where I should put the relays, though; I'm thinking with the signal paths, to the left, but this is the part of the design where both worlds connects... I was thinking of connecting the loop outputs to ground when they have nothing plugged in (I'm not sure this is feasible with only TRS, though). This way, no need to warn the PIC about it. Or I could wire the relays ground to the TRS, so that it would have no ground if nothing is plugged, which means that it won't activate, and the signal will bypass this particular loop. The only caveat is that this means that the audio signal and the relays power supply share the same ground. Any thoughts? The expression pedal inputs definitely need to be grounded if nothing's plugged, that hadn't escaped my attention :) As for channel switching, I don't think this is actually a problem, since this isn't something we hear, and having nothing plugged won't bother anyone. I was planning on using transistors for this, by the way, because they're cheaper than relays and this is not in the audio signal path. The CORE has its own regulator, so that's covered. I'll definitely add a regulator for the relays, now that you mention it. But I'm not sure what you mean about the audio path. There is nothing in the box that changes the audio signal, so there is no component (aside from the relays) that needs any kind of power supply.

Thanks for your input. Here are a few answers and more thoughts, in reaction to your post. 9V power supply and current draw) Ah, that explains why the wiki states that the higher the difference in voltage between the input to the 7805 and 5V, the more it's heating... I have a silly idea: if I keep my 1A 9V power supply but equip my box with another 7805, wired in parallel to the CORE one, and dedicated to powering the relays, won't I somewhat be able to get a bit more current than 1A at 5V from my 9V 1A power supply? Having 2 separate power supplies that plug into the same box would seem awkward to me... DIN module count) If I understood well, one DINX4 module can handle 32 digital inputs. If we take back the 10 (or 12) footswitches and a few more for the edition buttons and rotary encoders, that still leaves more than 10 inputs free, if I ever want to use TRS jacks. But frankly, I'm thinking that having something actually plugged into a loop if the loop is activated is something for the user to ensure. I don't think I really need to check that with the PIC. I'm keeping the idea in mind, though. other stuff) - the impedance converters yo uare talking about are, I think, what I labeled input and output buffers. I plan to use opamp buffers, with high quality opamps (Burr Brown) - I'm not sure if you're talking about shielded cables inside or outside the box - The digital and audio signal path are totally separated, that's the nice thing about using relays. Or did I get it wrong? - the stompboxes will use a separate "power brick", so no worries here - I've read stuff about star grounding and all, but I'm not very well informed on that matter, I'm kind of hoping (against hope) that it will all go well - separate audio and case ground, noted

Hello, I'm new here and I've started designing another take on the pedalboard design. You can find the current state of my project (along with a short introduction of yours truly) on the page I've started on the wiki: here. It's still an early draft, but all comments and thoughts are welcome.