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Amir,
At 03:58 PM 3/17/2004 -0500, adt22-at-drexel.edu wrote:
>Electromagnetic relays usually have a life span that is in the millions of
>switches. Although I can't find it now, I thought I saw a site stating
>SSRs were also rated for a minimum number of operations - is that true?
Life of standard relays is usually limited
by arcing of the contacts when they make
and break.
I do not know why SSRs would have a limited
number of cycles.
>Also what is the range in frequency you have with the PICs?
DC to about 1.5 KHz
Maximum PWM speed depends on CPU clock speed.
>Hypothetically if the SSR was good for 1 billion ops
>and you used a 1KHz frequency your SSRs would last ~275 hours which is
>pretty long. I'm sure many other things would fail before your 275 hour
>tune-up. But I just wanted to bring it up because others might want to
>consider the price and life of the SSRs when you are choosing a frequency.
$15 cost (from surplus vendors) divided by 275 hours is a bargain.
Joe
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