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New IDE Card


Shift838

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3 hours ago, Shift838 said:

I have installed a DC/DC Converter in place of the LM7805 voltage regulator.  Swapped out a couple of capacitors for the new design with the results below:

 

  • More stable 5v power output
  • much cooler

 

With LM7805 and heatsink after 2 minutes of powered up the regulator temperature ranges between 120 -130 degrees Fahrenheit.

 

With the new DC/DC Converter after 2 minutes of powered up the converter temperature ranges between 80 - 86 degrees Fahrenheit.

 

With that much of a difference in heat I believe it is worth using the DC/DC Converter over the standard LM7805 voltage regulator..

 

May I ask, what kind of a converter did you use, and any tips on using it?  The ones I used in the BATcomputer were extremely noisy, and I never was able to filter all of it out.  I think that was part of the BATcomputer's downfall.

K-R.

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19 hours ago, Kchula-Rrit said:

May I ask, what kind of a converter did you use, and any tips on using it?  The ones I used in the BATcomputer were extremely noisy, and I never was able to filter all of it out.  I think that was part of the BATcomputer's downfall.

K-R.

The one I used is P7805-2000R-S CUI Inc. | Mouser

 

I followed the typical schematic, but I did increase the voltages on the capacitors.  I took a recommendation from @InsaneMultitasker that he received from @Swimand another AtariAge member.  I changed the lower voltage cap to a higher voltage cap.  On the input side I used a 22uf 50v electrolytic.  On the output side I have a 22uf 25v ceramic and a .1uf 50v ceramic.

 

 

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2 hours ago, Shift838 said:

The one I used is P7805-2000R-S CUI Inc. | Mouser

 

I followed the typical schematic, but I did increase the voltages on the capacitors.  I took a recommendation from @InsaneMultitasker and changed the lower voltage cap to a higher voltage cap.  On the input side I used a 22uf 50v electrolytic.  On the output side I have a 22uf 25v ceramic and a .1uf 50v ceramic.

 

 

Thanks!  I just blew my computer budget for a while, so I will keep these in mind.  I like the idea of the higher voltage rating; all of mine are 50V units.  Back when I built computers, tantalum caps had a reputation for randomly burning, shorting-out, or exploding.  I assume they have fixed that problem?

K-R.

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9 hours ago, Kchula-Rrit said:

Thanks!  I just blew my computer budget for a while, so I will keep these in mind.  I like the idea of the higher voltage rating; all of mine are 50V units.  Back when I built computers, tantalum caps had a reputation for randomly burning, shorting-out, or exploding.  I assume they have fixed that problem?

K-R.

All caps can burn out or explode but when designing your circuits (IMO) I typically go with a little extra voltage than required for some headroom.

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Another update..

 

I found one signal error for the RTC power line.  it was connected to nothing.  although it would work, but would just use the battery power, so the battery would not last long at all.  fixed that.

 

I was having issues copying files and come to find out I had a 32k card in my test system that was acting up.  swapped it out and for the first test I copied over 100 MB to both the primary and slave CF card partitions.  Formatted all partitions again and selected my entire Infocom games directory which has all the current Infocom games in their separate directory, which is over 238mb and copied the entire directory to multiple partitions with no issues.

 

During the massive copy process I measure the heat generated on the DC/DC converter and it never got over 92 degrees Fahrenheit, pretty good, I think.

 

The IDE is running rock solid with all of my test.  My next test will be in the Geneve this weekend.  I have a free weekend from honey-do jobs so I can really hit it hard.  If all goes to plan (knock on wood) then it will be good to go for pre-orders.

 

If anyone wants a prototype (I have 4) please contact me and I will provide a workup price for them.  I will work up a price, just know that there will be one correction on the board for the RTC power.

 

There will be an option to either get my 838-RTC module or supply your own if you already have one or have a working BQ4847.

 

 

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I have completed my testing on both the TI-99/4A and Geneve with the new IDE card.  I have been able to exercise all functions for IO operations on both TI and Geneve.  With the Geneve, I had to use the development version of MDOS to address the IDE issue (v7.42).

 

Please note, the RTC chip that will be offered will be the 5v version as it supplies the voltage required for the SRAM control and the 5v version seems to be more stable, this does increase the price of the board by around $15.

 

Preorders will open soon.  I still want to put it through some more paces before on both the TI and Geneve.  

 

 

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