inductor substitution

[Uriah]

I have an small electric motor that has some kind of speed control pcb
attached to it. There are two inductors manufactured by Devalon
marked 4.7uH and 10% They are the size of a 1/4 resistor and solid
beige in color. My question is can I substitute a color wheel
inductors that are marked like resistors? Is there some brief rules
when it comes to inductors of this size and value and how to go about
substituting other inductors that look different but are the same
value.

hank you very much.

Russ

 

[Peter Bennett]

On Fri, 29 May 2009 17:20:53 -0700 (PDT), Uriah <uriahsky@hotmail.com>
wrote:

I have an small electric motor that has some kind of speed control pcb
attached to it. There are two inductors manufactured by Devalon
marked 4.7uH and 10% They are the size of a 1/4 resistor and solid
beige in color. My question is can I substitute a color wheel
inductors that are marked like resistors? Is there some brief rules
when it comes to inductors of this size and value and how to go about
substituting other inductors that look different but are the same
value.

hank you very much.

Russ

My first thought is that the value and tolerance are the important
items - the colour scheme can vary with the whim of the manufacturer.

One other item that may be significant is the current-carrying
capability - but you'd need to get the manufacturer's specs for the
original part to find its rating. A study of the circuit may suggest
the necessary current capability.


--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

 

[Russ]

Then except for the current rating can I use any inductor that
is the same value and tolerance? They sell some inductors that
are 4.7uH and 10% but are marked like resistors on ebay.

http://cgi.ebay.com/80-pcs-8-value-1uH-1mH-color-wheel-inductor_W0QQitemZ120427315600QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item1c0a070190&_trksid=p3286.c0.m14&_trkparms=72%3A1205|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A0|293%3A1|294%3A50

Would these work. I seem to having a hard time finding info on
all of the different types of inductors that look the same style.

Thanks again

 

[Nobody]

On Fri, 29 May 2009 21:27:05 -0700, Russ wrote:

Then except for the current rating can I use any inductor that
is the same value and tolerance?

The tolerance is unlikely to matter.

They sell some inductors that
are 4.7uH and 10% but are marked like resistors on ebay.

[snip]

Would these work. I seem to having a hard time finding info on
all of the different types of inductors that look the same style.

Yes, assuming that they can handle the current. But that's easier said
than done if you don't know the current rating for the existing inductor.
A search on Farnell's site for 4.7uH axial-leaded inductors shows parts
with current ratings from 320mA up to 1.6A.

E.g.:

4.7uH, 380mA, 3.3mm dia x 9.8mm long:

http://uk.farnell.com/epcos/b78108t1472k/inductor-axial-4-7uh/dp/513416

4.7uH, 820mA, 4mm dia x 9.2mm long:

http://uk.farnell.com/epcos/b78108s1472k/inductor-axial-4-7uh/dp/608464

The eBay listing says "about 4mm dia., 9mm length"; both of the above are
roughly that size, but one has over twice the current rating of the other.

You would be better off getting something with a known current
rating, preferably the highest rating which will fit into the
space available. Too high a current rating shouldn't be a problem (if it
is, your only option is to find an identical component), but too low a
rating could result in failure (not necessarily of the inductor, but
possibly of something more expensive).