Arachnid - Dual Eeprom

adolfo

New member
Thanks!

No, that’s a limitation of the fv-1 chip. The fv-1 only fetched the data from the eeprom when it detects a change on pins 16-18. Flipping the A/B toggle doesn’t affect pins 16-18, it just affects which eeprom chip will be active when the fv-1 fetches the data. So, when the toggle is flipped, the fv-1 doesn’t know to fetch new eeprom data until you move the rotary.

Hope this helps
Thanks !!!
 
So I’ve been looking at this and it seems based on the schematic drawn that the pins I marked in green should be connected together/toground as well but are not in the layout drawing?

Is this actually verified at this point?

I want to give it a shot.
 

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phi1

Well-known member
Thanks for the comment, yes those pins should also connect to ground. I didn’t link them in my layout, because my layout assumes you’re using pin headers (or resistor legs) to connect it to the pcb (squares on my layout). So pins 3&4 will connect to ground because the pin headers go to the pcb, and those pcb pads are grounded.

I did build it using that layout and it worked, I don’t think anyone else has. Careful the order you solder on the pots / this board.

Admittedly, it’s a little tricky connecting all those links on perf board like this. If I were to build it again I’d use vero (stripboard) using the layout from my pdf (aug 11 post, haven’t verified) or the one p_wats made (he built so it’s verified).
 
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Thanks to all who worked this out together here and shared enough info for me to put this together. It actually sat here unverified for a long while, I needed a second eeprom lol.

Finally got around to verifying it and all is perfect. The internal switch was simply to verify before drilling a hole and running wires to the pads.

If anyone wants one PM me to discuss, I guess I can’t keep them all to myself haha.
 

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phi1

Well-known member
Awesome! That is EXACTLY how I envisioned it working with a pcb. Would be much easier to solder the headers with pcb compared to vero or perf.
 

Sasan

Member
View attachment 11122
Thanks to all who worked this out together here and shared enough info for me to put this together. It actually sat here unverified for a long while, I needed a second eeprom lol.

Finally got around to verifying it and all is perfect. The internal switch was simply to verify before drilling a hole and running wires to the pads.

If anyone wants one PM me to discuss, I guess I can’t keep them all to myself haha.
WOW, this is aweome! I'd love to get one (if you ship internationally....I think I'd replace the internal switch with an on/on-toggle and put it on the outside of the enclosure...)
 
WOW, this is aweome! I'd love to get one (if you ship internationally....I think I'd replace the internal switch with an on/on-toggle and put it on the outside of the enclosure...)
The pads are meant specifically for that, as I mentioned I placed the switch to verify the pcb was working correctly before drilling hole into enclosure, just in case.

👌🏼PM me for contact info, I will sell you one.
 

heretop

New member
I am going to try this but with three eeprom, with this switch to switch between three eeprom. Will it work or any suggestion?
1620141214973.png
 

heretop

New member
That should work. In the thread I made a while ago about this idea, @PedalPCB mentioned that he might make daughterboards for both that configuration and for a 1p8t rotary switch.
Thanks for reply! I think 3 is a good middle number. To have 8, need smd and another rotary switch (so he probably need to redesign the pcb, a daughterboard will need some weird location for the 1p8t, I don’t see how can he do it unless he change the position of holes for pots). Smd is not something I prefer for eeprom. And maybe will have 7 rotary control in front panel (2 1p8t and 5 pots).
 

phi1

Well-known member
Yeah I’m kinda with you there, a toggle switch can be snuck into the 125B build with the current layout. 2 or 3 banks is probably as high as I’d want to go personally. Though a 64 patch diy project is an epic concept.
 

heretop

New member
Yeah I’m kinda with you there, a toggle switch can be snuck into the 125B build with the current layout. 2 or 3 banks is probably as high as I’d want to go personally. Though a 64 patch diy project is an epic concept.
Yeah. May I ask you that do you think I can fit a on-on-on switch which have 2x3 pins, so its width is 0.46inch/11.8mm instead of 0.265inch/6.7mm of original 3 pin switch. Thanks.
 

phi1

Well-known member
Hmm to be honest I’m not sure. I don’t have the unit pictured any more to look at for reference. If I recall right it was a tight squeeze just for the single row toggle. You could consider mounting the switch on the side, or below the rotary. In this case it’s be above the pcb, which toggle switches don’t quite fit in the same height of normally mounted pots. There’s some extra length on pot and rotary switch pins so you could make the pcb a bit higher, not sure if that would give you enough to fit the toggle. Or put a short shaft sw right next to the stomp. Seems dangerous, but I’ve done it and thought there wasn’t really any chance of stomping the switch. Though that might not be ideal for you aesthetically.
 

heretop

New member
Hmm to be honest I’m not sure. I don’t have the unit pictured any more to look at for reference. If I recall right it was a tight squeeze just for the single row toggle. You could consider mounting the switch on the side, or below the rotary. In this case it’s be above the pcb, which toggle switches don’t quite fit in the same height of normally mounted pots. There’s some extra length on pot and rotary switch pins so you could make the pcb a bit higher, not sure if that would give you enough to fit the toggle. Or put a short shaft sw right next to the stomp. Seems dangerous, but I’ve done it and thought there wasn’t really any chance of stomping the switch. Though that might not be ideal for you aesthetically.
I have thought about it, I will try to get a 2x3 pin switch first and test the width. Worst case scenario, some logic gate and a 1x3 on-off-on switch will work.
 
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heretop

New member
Hmm to be honest I’m not sure. I don’t have the unit pictured any more to look at for reference. If I recall right it was a tight squeeze just for the single row toggle. You could consider mounting the switch on the side, or below the rotary. In this case it’s be above the pcb, which toggle switches don’t quite fit in the same height of normally mounted pots. There’s some extra length on pot and rotary switch pins so you could make the pcb a bit higher, not sure if that would give you enough to fit the toggle. Or put a short shaft sw right next to the stomp. Seems dangerous, but I’ve done it and thought there wasn’t really any chance of stomping the switch. Though that might not be ideal for you aesthetically.
1620199912738.png
Here is a schematic I draw with a NAND gate. Any suggestion? Thanks
 

phi1

Well-known member
Any value will work fine, from 10k to 100k (and beyond to some extent).

Basically, if pin1 is connected to ground, then pin1 is at 0v. Current flows from 3.3v to ground through the resistor. (If 10k, I=0.33mA of wasted current, not significant in my opinion, higher resistor is less current through this path).

if pin 1 is not grounded, then pin1 will sit at about 3.3v, pulled high through the resistor (called pull-up resistor). Technically, it’s a voltage divider formed by the resistor and the input impedance of the chip pin1. I don’t know what this impedance is actually, but I assume it’s high enough that 100k resistor keeps it plenty close to 3.3v.

the same idea (pull-up or pull-down resistor) is used on the arachnid for pins 16-18 (program selection), and pin13 if you choose to add a switch to ground pin13 for fv-1’s stock internal patches.
 

JamieJ

Well-known member
Any value will work fine, from 10k to 100k (and beyond to some extent).

Basically, if pin1 is connected to ground, then pin1 is at 0v. Current flows from 3.3v to ground through the resistor. (If 10k, I=0.33mA of wasted current, not significant in my opinion, higher resistor is less current through this path).

if pin 1 is not grounded, then pin1 will sit at about 3.3v, pulled high through the resistor (called pull-up resistor). Technically, it’s a voltage divider formed by the resistor and the input impedance of the chip pin1. I don’t know what this impedance is actually, but I assume it’s high enough that 100k resistor keeps it plenty close to 3.3v.

the same idea (pull-up or pull-down resistor) is used on the arachnid for pins 16-18 (program selection), and pin13 if you choose to add a switch to ground pin13 for fv-1’s stock internal patches.
Thanks @phi1 - I can’t wait to get mine built.
 
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