4 ms·

The traditional fix back in the 1980s was to use Tantalum capacitors which had good high frequency response. Unfortunately they turned out to be dependent on op

The traditional fix back in the 1980s was to use Tantalum capacitors which had good high frequency response. Unfortunately they turned out to be dependent on oppression for their source material and also tend to short at the smallest possible disturbance. The cheap option was an electrolytic cap and a .1 uF disc ceramic. The self inductance of a wound aluminum capacitor tended to be ok at 120 hz hum frequency but horrible at higher frequencies found in TTL and CMOS logic. Those also turned out to self destruct over time due to the extensive use of an incomplete stolen trade secret electrolyte formula in many low cost capacitors. I'd still use both, personally.

Aurornis 2y ago
Tantalum and electrolytic capacitors are primarily for bulk storage and lower frequencies. They don't substitute for small ceramic capacitors in this context. Switching regulator frequencies have become much higher since the 80s. It's common to have switching regulators operating in the MHz range with small ceramic output capacitors and relatively low value inductors.
- numpad0 2y ago
  I think the setup in GP is something like 0.1uF tantalum + 47uF electrolytic. 0.1uF stops CPU crashing and electrolytic stops CPU passing out. Tantalum fails in shorting mode and have since been replaced with ceramics that fail open, of course.
  - Aurornis 2y ago
    > I think the setup in GP is something like 0.1uF tantalum + 47uF electrolytic. 0.1uF stops CPU crashing and electrolytic stops CPU passing out. You might find a configuration like that in some old retro computing gear, but a modern 1uF ceramic chip capacitor will outperform a 0.1uF tantalum significantly. You don't need to use an electrolytic for 47uF. You can get 47uF in one or two surface mount ceramic caps.
    - mikewarot 2y ago
      I was surprised to find that you can, indeed, get 47 uF 35 volt MLCC surface mount caps, but they'll set you back about 10x the cost of the same capacitance in a surface mount electrolytic. In some cases, it might be worth it. Most of the repairs I do are to older test equipment and radios, from WWII to the end of the 20th century. Some of the new surface mount stuff is just too small for us to work with. 6TTSOP is a chip 2 by 1.25 mm, and it's really hard to tack leads onto it to patch it into an existing circuit. (We needed 20+ dB of gain at 2 Ghz to replace an obsolete part, we ended up ordering a MAR-6+ instead, at least it's big enough to solder)
      - IX-103 2y ago
        You should probably stock up on breakout boards in your most frequently used chip form factors. They're usually fairly cheap and can save you most of the pain of avoiding shorting pins on floating chips.
    - numpad0 2y ago
      True. Couple big ceramic caps on the secondary side of power circuit and cheapest 0.1uf peppered around is going to make sense. Chip mounter machines probably like it too.

Aurornis 2y ago

Tantalum and electrolytic capacitors are primarily for bulk storage and lower frequencies. They don't substitute for small ceramic capacitors in this context. Switching regulator frequencies have become much higher since the 80s. It's common to have switching regulators operating in the MHz range with small ceramic output capacitors and relatively low value inductors.

numpad0 2y ago
I think the setup in GP is something like 0.1uF tantalum + 47uF electrolytic. 0.1uF stops CPU crashing and electrolytic stops CPU passing out. Tantalum fails in shorting mode and have since been replaced with ceramics that fail open, of course.
- Aurornis 2y ago
  > I think the setup in GP is something like 0.1uF tantalum + 47uF electrolytic. 0.1uF stops CPU crashing and electrolytic stops CPU passing out. You might find a configuration like that in some old retro computing gear, but a modern 1uF ceramic chip capacitor will outperform a 0.1uF tantalum significantly. You don't need to use an electrolytic for 47uF. You can get 47uF in one or two surface mount ceramic caps.
  - mikewarot 2y ago
    I was surprised to find that you can, indeed, get 47 uF 35 volt MLCC surface mount caps, but they'll set you back about 10x the cost of the same capacitance in a surface mount electrolytic. In some cases, it might be worth it. Most of the repairs I do are to older test equipment and radios, from WWII to the end of the 20th century. Some of the new surface mount stuff is just too small for us to work with. 6TTSOP is a chip 2 by 1.25 mm, and it's really hard to tack leads onto it to patch it into an existing circuit. (We needed 20+ dB of gain at 2 Ghz to replace an obsolete part, we ended up ordering a MAR-6+ instead, at least it's big enough to solder)
    - IX-103 2y ago
      You should probably stock up on breakout boards in your most frequently used chip form factors. They're usually fairly cheap and can save you most of the pain of avoiding shorting pins on floating chips.
  - numpad0 2y ago
    True. Couple big ceramic caps on the secondary side of power circuit and cheapest 0.1uf peppered around is going to make sense. Chip mounter machines probably like it too.