[Amps] Filter capacitors

[Robert Logan via Amps]

Bill, sounds like the adverse effects for obscure medicines advertised on TV!  But good cautionary info.  Thanks.  Bob

Sent from my iPhone

On Apr 22, 2014, at 5:04 PM, Bill Turner <dezrat1242 at wildblue.net> wrote:

ORIGINAL MESSAGE:          (may be snipped)

On 4/22/2014 2:39 PM, Robert Logan via Amps wrote:
> Are there any adverse effects to doubling the capacitance (leaving voltage ratings at spec) of an electrolytic in a 300 or an 800 voltage power supply?   I have new ones on hand to replace old, leaky ones.  Thanks for any advice.  Bob NZ5A

REPLY:

There are several adverse effects but none of them are necessarily show stoppers if you take them into account and make some changes as needed:

1. Since you already have them on hand, the cost is not an issue but otherwise it would be. Also size.
2. You may need a more robust step-start circuit. The resistor especially may need to have a higher wattage and/or resistance rating.
3. Longer bleed-down time after shutoff before it is safe to work on the supply.
4. In case of an arc, more energy is dumped into the arc with possibly greater damage, especially to meters if not properly protected.
5. Any glitch limiting resistor must be more robust to avoid being damaged itself.
6. Unless properly rated, fuses may explode instead of just opening normally.

Those are the main adverse effects that come to mind. There may be others.

73, Bill W6WRT


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