Different kind of resistors?

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Osse

Well-known member
Joined
Dec 2, 2007
Messages
81
Hello good folks.

I've been trying to search the forum and the net, but havn't found any good simple explanation on different kind of resistors, and their specific attributes and characters.

What resistors is mostly used in audio electronic cirquits? Can anyone give me a little explanation(or a link) of good info on this(is there any books explaining this out there?).

I feel lost in space in all this... :shock:

Thanks!
 
[quote author="Osse"]
I feel lost in space in all this... :shock:
Thanks![/quote]
Well... Wait until you discover that there are different kinds of capacitors too!
:green:
If you search on this forum, you will find interesting threads about resistors like this:
http://www.groupdiy.com/index.php?topic=27843
 
[quote author="Osse"]Hello good folks.

I've been trying to search the forum and the net, but havn't found any good simple explanation on different kind of resistors, and their specific attributes and characters.

What resistors is mostly used in audio electronic cirquits? Can anyone give me a little explanation(or a link) of good info on this(is there any books explaining this out there?).

I feel lost in space in all this... :shock:

Thanks![/quote]

Well, let's start from physics. Which parameters of resistors may be critical?

We know about:
1. Resistance
2. Capacitance
3. Inductance

1: desired parameter, 2 and 3 - parasitic parameters.
Any wire have all of them. Resistor may be viewed as a conductor made of high bulk resistivity material. To get more resistance we need longer and thinner conductor made of higher bulk resistivity material. To get less resistance, contrary, bulk resistivity must be lower, it should be shorter and thicker. If we take a long wire it will have big inductance and capacitances between turns. Inductances and capacitances add frequency dependence, that may be too big for particular band of frequencies.

Resistors work transforming electric energy to heat. It means, they are getting the wormer the more power dissipate, accumulate heat energy, that is radiated to the environment both by rays and convection (heated particles of air fly up). It means, that the current that flows through them heat them, then an environment takes this heat cooling them. When conductors are heated they increase in size, so their resistance changes. It means that resistors are slightly non-linear. Special constructions were implemented to make their resistances less dependent on dissipated power. For example, now famous Vishay corporation started from making bulk foil resistors of special construction that are very linear and temperature stable, with small inductance. Such small stable resistors were needed for electronics flying in cosmos: thermal variations are big, space is costly.

Another approach that is used when cost means more than size, is to use resistors rated for higher power: in such case variations of temperatures that means variations of resistances will be much less, and time constants longer (non-linear effects will go down below audible band of frequencies, introducing very slight thermal compression).

I personally prefer metal film resistors rated for higher powers than I need to dissipate. However, I mean most critical places, where linearity and temperature stability are critical.
 
Back
Top