838 Drive Select Board

[Shift838]

I finally sat down today and hashed out a new prototype as I did not want to open my system up and get the one out I am using..

 

The Drive Select board functions as expected and it will stop all of us from cutting and making custom cables. a Standard straight through floppy cable (no twist will work).

 

I have tested this one and it works. My next step is to order some boards.

 

 

I have tested Reading, Writing and Formatting diskettes.

 

This just plugs into the back of the 3.5 drive and the cable from the FDC plugs in the other side. Select the drive # with the dip switch.

 

I included Drive #2, although you don't need this unit as a straight through cable will default to DSK2, i did it to keep numbering consistent for the dip switch.

Edited July 30, 2018 by Shift838

[fabrice montupet]

I have tested this one and it works. My next step is to order some boards.

I have tested Reading, Writing and Formatting diskettes.

 

Do you have also tested a serie board?

 

Traces seems to me too thin to drive some drive signals. The trace/pad clearances you have chose are very thin too. A high quality manufacturer is necessery, if not, during the copper removal step, this clearance choice may cause a trace to run over onto a another trace or pad and make short circuit the PCB.

It's just a personal point of view.

[+Ksarul]

Yeah, those trace widths worry me too. I try to stay with traces no narrower than .010 inches, with the same clearance between other traces and pads. it is usually safe to go down to .006 with most manufacturers, but I tend to use the larger clearances to avoid manufacturing issues.

[+helocast]

I finally sat down today and hashed out a new prototype as I did not want to open my system up and get the one out I am using..

 

The Drive Select board functions as expected and it will stop all of us from cutting and making custom cables. a Standard straight through floppy cable (no twist will work).

 

I have tested this one and it works. My next step is to order some boards.

 

 

I have tested Reading, Writing and Formatting diskettes.

 

This just plugs into the back of the 3.5 drive and the cable from the FDC plugs in the other side. Select the drive # with the dip switch.

 

I included Drive #2, although you don't need this unit as a straight through cable will default to DSK2, i did it to keep numbering consistent for the dip switch.

 

... of course the "why" behind how this works:

[Shift838]

Yeah, those trace widths worry me too. I try to stay with traces no narrower than .010 inches, with the same clearance between other traces and pads. it is usually safe to go down to .006 with most manufacturers, but I tend to use the larger clearances to avoid manufacturing issues.

 

I went back and checked and in deed my traces were too thin. I have changed them to the recommended .010.

 

uploaded new render in first post.

 

I forgot I put on a new version of Eagle on my laptop and forgot to change the design rules on this one.

 

Glad I got you guys here to check me!

Edited July 30, 2018 by Shift838

[Shift838]

 

... of course the "why" behind how this works:

 

exactly. the whole idea behind this is because the newer 3.5 drives do not have drive select jumpers any longer.

[+helocast]

 

exactly. the whole idea behind this is because the newer 3.5 drives do not have drive select jumpers any longer.

LOL. I ran into this after buying a pair of 3.5" off eBay with the intention to split them up between two PEBs, but the cable he supplied had a twist for "A", not a PC twist and not even a TI twist.

I'm not sure what it was ...

[Shift838]

i have ordered a small test run (3 boards) to make sure the circuit is good on the PCB.

[Shift838]

The prototype drive board arrived today. Soldered 2 up and they both work great.