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jbilander / SDBox-Mini

SDBox Mini for Amiga, compatible with the new updated card-detect firmware
GNU General Public License v3.0
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Added electrical safety for the Amiga #3

Open patrikaxelsson opened 1 year ago

patrikaxelsson commented 1 year ago

This is a feature request.

You should always turn off the Amiga and turn of the power supply to the SDBox before removing it from the Amiga, to prevent any damages.

Would it be possible to increase the electrical safety of the Amiga when using the SDBox by doing something similar to what @salocinx has done with his Plipbox deluxe, where he added a PhotoMOS solid state relay to make sure the SDBox always is turned off when the Amiga is turned off?

jbilander commented 1 year ago

We had that as an option on V1 when powering via the barrel-jack but no-one seems to like it and many clones removed the option completely. The easy way to have the SDBox powered when the Amiga is powered (and vice versa) is to take the 5V from the external floppy port, problem solved and it's quite easy to make a cable for this purpose, but of course not everyone has this external port available (or a pass-through port available on an external floppy-drive).

It could maybe be added if you can find a free spot on the PCB?. The Mini is a very small and crowded PCB.

salocinx commented 1 year ago

I will make my own SDBox PCB design public as soon as I fixed a small cosmetic defect. It includes the PVG612 PhotoMOS relay and an additional LED indicating whether a card is inserted or not (in total 3 LEDs: power, card-present, transfer-activity). These LEDs are controlled directly by their respective signals using transistors, so no need to change software.

patrikaxelsson commented 1 year ago

To be clear the idea was to just cut the 5V supply from the microUSB connector, not add a barrel jack. I don’t know if that was what you meant, but to be clear.

I have no skills whatsoever in PCB layout, but looked at some small variants of PhotoMOS relays and perhaps the AQY282SX could fit on the underside near the microUSB connector and regulator? It is a SOP-4 and claims to be 4.4x4.4mm with a height of 2mm. Handles 0.5A up to 60V and is currently manufactured.

salocinx commented 1 year ago

@patrikaxelsson I left out the barreljack on my SDBox, the PVG612 interrupts the 5V voltage of the USB port, which supplies the SDBox, controlled by the 5V line of the parallel port (cp. attached image). The AQY282SX looks like a good fit, thanks.

IMG_2797

jbilander commented 1 year ago

AQY282SX looks good. I haven't gone through the datasheet in detail but looks good at first glance.

@patrikaxelsson I didn't mean the Barrel-jack should be added just the same functionality but instead for the microUSB-jack as you say. What I mean is it can be tricky to fit a component like the AQY282SX and get the 5V routed through from pin 14 (Amiga's 5V) in the parallel port to the USB area. It is a tiny two layer board pretty much jam-packed as it is now, but I haven't actually checked. Perhaps it is possible but my "feeling" is it would require to go to 4 layers which increases PCB cost which may be acceptable. Perhaps if anyone looks into making this we could change the USB-socket to a TH-type as well (for mechanical strength purpose). I don't think switching to a USB-Mini-jack or USB-C type jack fits even though that would be preferable/more robust, they are too big for the Mini PCB. I don't have any spare time for doing this at the moment though, or rather I prioritize other projects right now, but feel free to tinker with this if anyone wants.