Questions about Meow Toast battery replacement

[bigmessowires]

MeowToast is an adapter that replaces Macintosh 3.6V logic board batteries with a CR2032 coin cell. It's here on Etsy, but sold out.

It is open source licensed and the design files are here, but this is an older version of MeowToast that uses two coin cells and some diodes. Or maybe I'm confusing MeowToast with MeowTWOast which is designed for 5V. Which Mac models need a 5V battery?

Either way, if I am getting some PCBs made on my own, I'm unclear on how this gets inserted into the battery holder. Are the edges of the PCB supposed to be copper plated? The photos on the Etsy site don't really explain it very well. This looks like the contact on the right side of the battery holder is touching the CR2032 holder, but nothing is touching on the left side. I feel like I'm missing some important detail.

 

[Phipli]

MeowToast is an adapter that replaces Macintosh 3.6V logic board batteries with a CR2032 coin cell. It's here on Etsy, but sold out.

It is open source licensed and the design files are here, but this is an older version of MeowToast that uses two coin cells and some diodes. Or maybe I'm confusing MeowToast with MeowTWOast which is designed for 5V. Which Mac models need a 5V battery?

Either way, if I am getting some PCBs made on my own, I'm unclear on how this gets inserted into the battery holder. Are the edges of the PCB supposed to be copper plated? The photos on the Etsy site don't really explain it very well. This looks like the contact on the right side of the battery holder is touching the CR2032 holder, but nothing is touching on the left side. I feel like I'm missing some important detail.

View attachment 63668

Rotate it axially by 90°

Thinking of SiliconInsider's board.

 

[Phipli]

MeowToast is an adapter that replaces Macintosh 3.6V logic board batteries with a CR2032 coin cell. It's here on Etsy, but sold out.

It is open source licensed and the design files are here, but this is an older version of MeowToast that uses two coin cells and some diodes. Or maybe I'm confusing MeowToast with MeowTWOast which is designed for 5V. Which Mac models need a 5V battery?

Either way, if I am getting some PCBs made on my own, I'm unclear on how this gets inserted into the battery holder. Are the edges of the PCB supposed to be copper plated? The photos on the Etsy site don't really explain it very well. This looks like the contact on the right side of the battery holder is touching the CR2032 holder, but nothing is touching on the left side. I feel like I'm missing some important detail.

View attachment 63668

Oh, I realise what you're saying. No, neither side touches the battery holder, they're both touching plated contacts on the ends of the PCB.

 

[bigmessowires]

How does one get a plated contact on the edge of the PCB? I don't think that's a standard option. It looks like the MeowToast PCB uses three castellated holes at the edge, but I can't imagine that would make reliable contact with the battery connector unless you filled it with solder by hand. MewTWOast looks like it has actual plated edges on the PCB.

 

[Phipli]

How does one get a plated contact on the edge of the PCB? I don't think that's a standard option. It looks like the MeowToast PCB uses three castellated holes at the edge, but I can't imagine that would make reliable contact with the battery connector unless you filled it with solder by hand. MewTWOast looks like it has actual plated edges on the PCB.

View attachment 63669

You make a rounded rectangle plated through hole half on, half off the board, then the board house mill or score through the middle of it.

The one time I did it they grumbled my board was too small. (It was about 20mm by 10mm)

 

[volvo242gt]

Here are a couple images of one, first loose, and second, installed on a Wombat board (C650 in this case). The edges of the meowTOAST look to be tinned, where the contacts are. @Geekybit can elaborate, since they're his design.

-J

 

[bigmessowires]

Thanks, I'm sure I'm simply over-thinking it. I've ordered some PCBs and I'll figure it out once they've arrived.

 

[s_pupp]

I’ve had better success with SiliconInsider’s horizontal version. I had trouble getting my MeowToast to stay put in a Mac Classic. It popped out of place very easily. I rolled heated moldable plastic beads into twi balls, and placed one on each side between the MeowToast and edges of the battery holder. I secured the whole shebang with friction tape. It looks like a 7 year old’s fix, but it works.

 

[Forrest]

The picture of the purple MeowToast was created with plated oval slots at the ends of the board, and during final routing the slots were cut in half. Speaking as a former PCB manufacturing engineer, it’s a good design.

 

[jmacz]

I made my own battery cover for use with the MeowToast so that it stays put. With the stock cover, it will easily pop out.



I shared the STL previously here:

https://68kmla.org/bb/index.php?threads/jmacz-mac-iifx-project.45083/post-498954

 

[bigmessowires]

Nice. Between this, 3d-printed interrupt/reset buttons, and 3d-printed face plates, I may need to reconsider my position on having a 3d printer.

BTW, your footprint for C10 is empty and it's triggering my OCD.

 

[aeberbach]

Nice. Between this, 3d-printed interrupt/reset buttons, and 3d-printed face plates, I may need to reconsider my position on having a 3d printer.

I originally bought a 3D printer to solve the problem of positioning a replacement keyboard inside an Amiga 1200, but these days I do more printing and designing than vintage computing. It's a lot of fun!

 

[volvo242gt]

Nice. Between this, 3d-printed interrupt/reset buttons, and 3d-printed face plates, I may need to reconsider my position on having a 3d printer.

BTW, your footprint for C10 is empty and it's triggering my OCD.

IIfx has either tants or electrolytics at that location, so... ;-) Attached is a photo of my old IIfx's board when I got it in the mail. Current IIfx has tants on the other pads for C10 and C27.

 

[Breathing]

Hello there!
I had the same "need" a year ago and I solved all of this with my own PCB design for a vertical placement and recently secured the adaptor with 3D printed parts covering the battery compartment.
Yes, the PCB needs to be manufactured with side copper coating, and to increase the contact surface I did double the PCB so it's thicker.




The Gerber files are attached, this is what I used with PCB Way (Not a sponsorship ). The order details were as follow:

 

[Breathing]

And here is the same PCB CR2032 adapter but with my 3D-printed socket to make a perfect fit. I can even replace the CR2032 without having to move the adapter.
On some Macintosh II where both batteries are mounted side by side, I had to make a special version of the 3D part. All machines work like a charm no need for 2 CR2032 or a diode.

 

[Breathing]

@bigmessowires If you go with the PCB I proposed, you would need the following CR2032 holders:
BAT-HLD-001-THM From TE Connectivity (Mouser: https://mou.sr/3Qlr9Ol)

3D holders (Single and Dual) are in attachment. I use PETG for the part with 0.12mm (0.4mm nozzle)

 

[Breathing]

Sorry for the SPAM but I finally took the time to publish the 3D model online (and PCB):

Printables

www.printables.com

 

[jmacz]

BTW, your footprint for C10 is empty and it's triggering my OCD.

Haha. +1 on what @volvo242gt said. There were two sets of pads for some of the caps.

 

[jmacz]

And here is the same PCB CR2032 adapter but with my 3D-printed socket to make a perfect fit.

This looks nice!

 

[bigmessowires]

I like the idea of doubling the PCB for more contact area and stability; I'll try that. OSH Park is a good way to order these, since the cost is entirely dependent on PCB size and these are tiny. It's just $3.20 including shipping for three PCBs.