# Basic question about electronic components

Discussion in 'Electronic Design' started by [email protected], Jan 8, 2006.

1. ### Guest

Hi all:

This it is a question that perhaps all have faced:

What happens if in a certain project resistors of 1/4W are substituted
by resistors of 1/2W or are mixed

What happens if in a certain project capacitors of 25V are substituted
by capacitors
of 50 V or vice versa?

Do you think that affects the entire project?

Thanks in advance for any comment.

2. ### Joel KolstadGuest

In 'generic' low frequency circuits, nothing. When you start playing RF
games, parasitics _may_ be significant in the circuit design and you can
change the circuit's behavior.
Pretty much the same answer: In general, nothing. In some fancier designs
(e.g., switching power supplies), the difference in ESR may cause something
to go haywire.
Depends entirely on the project. What is it? In 90+% of all projects,
probably not -- but there are plenty where it would.

---Joel Kolstad

3. ### NickGuest

What happens if in a certain project resistors of 1/4W >>are substitutedSimply putting it 1/4 W resistors can be replaced by 1/2W resistors, in
90% cases. But doing so is not friutful for their size concern and also
their cost. Here one has to take care to keep the tolerences same as
much as possible. For 1/2W being replaced by 1/4W, the power dissipated
through the resistor should not exceed the rating or the rsistor will
burn.The first case will not affect the circuit working, but the second case
might have to be looked into. The circuit max. voltage where the
particular capacitor is used should not exceed the absolute max.
ratings(reducing by 10% for additional safety) of the capacitor. If
this care is not taken the capacitor may simply burst.

Regards
Nick

4. ### Rich GriseGuest

But, if they originally called out 1/2 watt resistors, there's probably
a good enough reason that they needed that rating that I wouldn't
recommending substituting a 1/4 watt in its place.
In the "vice versa" case, here, no, probably not. If you put a 25V cap in
a circuit that's spec'd for a 50V, you run a very real risk, or possibly
the certainty, of blowing up the cap. Other than that, Joel Kolstad is
right.
I concur here.

Cheers!
Rich

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