Tuesday 30 May 2017

Axial capacitors






In light of Axial capacitors being harder to find, not very good spec, or simply stupid prices, I came up with this little adapter board design.

The cost cost of the "kit" turned out a lot higher than I had initally thought and thus did not intend to put this into production. Though several people expressed interest in these, so I made a few up which are now available in my store. 

The main challenge was finding some small enough capacitors with a good enough ESR rating. The 4,700uF capacitors are used on my Atari's from the ST to STE, to Falcon so this design is a one size fits all type solution, at least for the 4,700uF value.

The overall size of the board isn't any larger than the existing axial capacitor. While the 4,700uF original probably has a pretty bad ESR figure, my boards value is 5,440uF @ 7.6Amps.

I tested this on a STE motherboard and it really helped with stability , in particular the floppy drives motor generally casues a dip in voltage and this simple board helps reduce that and increases stability of the system overall.

I am also aware of many other axial's from 2,200uF down to 100uF (and possibly lower on the Falcon). Smaller boards could be done to replace them all with basically ceramic based cap-boards. At least then they would never degrade over time like electrolytics do. This is on my "to do list" but likely isn't going to be done any time soon.

Direct store link
https://www.exxoshost.co.uk/atari/last/storenew/#0090

3 comments:

  1. I think as time goes on more and more replacements like this will have to be made as I am sure the old parts supply either dries up or sky rockets in price.

    What about those tiny SMD cap type things?

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    Replies
    1. There are things like 6.3V 100uF ceramics, its what I was intending to replace all the smaller value electrolytics with on machines like the falcon. Though such caps can be like £5 each, so 4,700 value would need 47 of them x £5 each = £235! I don't think anyone is going to buy any :)

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  2. "£235! I don't think anyone is going to buy any :)"

    Mega ouch!
    Seen the price of Falcons though that's a investment :p
    Would have thought the Chinese would have dragged them parts down to there usual marketing levels by now, seems not.

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