[pure-silver] Re: Worlds Fastest Camera Defies Gravity...
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Sun, 5 Jun 2005 17:15:46 -0700
----- Original Message -----
From: "Peter Badcock" <peter.badcock@xxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Sunday, June 05, 2005 4:47 PM
Subject: [pure-silver] Re: Worlds Fastest Camera Defies
Gravity...
> From my experience, (electrolytic) capacitors burn (or
> more likely explode!)
> when either
> i) you apply a sufficiently high voltage to it (i.e.
> somewhat more than it
> is rated to), or
> ii) the polarity is reversed.
> In your flash unit (i) could have happened if some other
> part of the
> circuit went bunkum , or someone plugged it in to a power
> supply that was
> higher than its rated voltage.
> (ii) could have happened if someone plugged the power
> supply in the wrong
> way around.
> Flash units have very high voltage electrolytic capacitors
> in them (usually
> 200-300V), which means if you replace the cap, just be
> careful when testing
> it out.
> I used to blow up capacitors for fun when I was a kid, and
> also
> accidentally when building my thesis project's power
> supply! Tantalum
> capacitors give the biggest bang for your buck.
> regards
> Peter Badcock
> On 6/6/05, Ray Rogers <earthsoda@xxxxxxxxx> wrote:
>>
>> and I was thinking I might be able to figure
>> out type and value of the burnt out capcitor
>> and replace it...
>>
>> of course, it might be wise to figue why it burnt out
>> in the first place.
Electrolytic caps are notorously unreliable. The voltage
rating of the capacitor will stay at its rated value only so
long as the capacitor is used. If its left unused for a long
time, or used at a lower voltage, it will become a lower
voltage capacitor and may overheat and blow up when rated
voltate is applied. One way of avoiding this when firing up
some piece of equipment that has been in storage for a long
time is to connect it to the mains through a variable
transformer, preferably one with a current meter. The line
voltage is brought up slowly while watching the meter. If it
jumps or otherwise indicates high current the thing should
be shut off. The slow applicaton of voltage allows the
chemical electrode to re-form.
Electrolytic capacitors have the advantage of
compactness. Other types of capacitor are superior but
larger, often much larger.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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