Can use RADIAL wound inductor instead of AXIAL? - Page 1
Forum section: electronics / beginners

author: hurricanehenry
author_rank: Regular Contributor
timestamp: April 25, 2023, 12:45:30 am
content: Hi, I am going through one of the self learning textbooks (Complete Electronics Self-Teaching Guide) and in Experiment 9.1 it calls for a 0.5 mH inductor.I bought one from Mouser but it turns out it is an RADIAL wound inductor, and it has 4 leads. I checked continuity with my DMM and there are two wires wrapped around the donut, resulting in 4 leads.The experiment shows an AXIAL inductor wrapped around a ferrite core.For the radial one I have, I tried to use my LCR but it doesn't seem to be able to measure its inductance. It is jumping all over the place (it measures other smaller inductors just fine).I was thinking of soldering the leads together to form 2 leads, to make it seem like the axial one, but not sure about it yet.I am also wondering how I can measure the inductance using my oscilloscope, and how I would even connect to the leads.Any advice?(Please see pics)

author: edavid
author_rank: Super Contributor
timestamp: April 25, 2023, 01:21:16 am
content: You are using the wrong terminology. The first one is a toroid, and the second one is a solenoid.The toroid is actually a transformer, not an inductor. Give us the Mouser link.

author: TimFox
author_rank: Super Contributor
timestamp: April 25, 2023, 02:48:25 am
content: Inductors can be wound around either a cylinder (solenoid) or a torus (toroidal).Two or more inductors on the same core with substantial overlap (and coupling) make a transformer.If you have two inductors, there is a third parameter called the mutual inductance that describes the coupling, along with the "self inductance" of each inductor.These concepts are covered in the usual textbooks.

author: hurricanehenry
author_rank: Regular Contributor
timestamp: April 25, 2023, 02:53:45 am
content: Here is the mouser link for the part.https://mou.sr/3AojiXsCommon Mode Chokes / Filters 250V 0.5mH 15A DCR=8mOhmsDatasheethttps://www.mouser.com/datasheet/2/212/1/KEM_LF0010_SC-JH-1104039.pdf

author: james_s
author_rank: Super Contributor
timestamp: April 25, 2023, 05:55:20 am
content: It says right in the description what it is, a common mode choke. It's for filtering on the incoming line voltage into a switchmode power supply, it prevents high frequency hash from leaking back out into the power line. It's a pair of inductors on a common core. It's designed to be deliberately lossy at high frequencies, which may or may not matter depending on what you're trying to do.

author: hurricanehenry
author_rank: Regular Contributor
timestamp: April 25, 2023, 07:20:19 am
content: It's for the experiment in the book to make the tank circuit part of a Colpitts oscillator. I don't know the resonant frequency, it's what is supposed to be measured after the circuit is running.Can I solder the two wires together to form a two leads component?

author: Swainster
author_rank: Frequent Contributor
timestamp: April 25, 2023, 08:26:41 am
content: As I understand it, the main inductance value for a common mode choke refers to the common mode inductance. This can be measured by connecting one side of the choke to an LCR meter and leaving the other side floating, however if you short the input leads together, and separately short the output leads (i.e. dont short across the coils), then it should give roughly the same inductance.That said, this is a very poor choice for an oscillator due to the reasons mentioned by james_s (lossy, i.e. low Q)

author: james_s
author_rank: Super Contributor
timestamp: April 25, 2023, 05:01:11 pm
content: If you want to try using that choke, use two of the terminals that are connected to one winding and ignore the other winding.Otherwise this is probably what you want:https://www.mouser.com/ProductDetail/API-Delevan/2500R-14J?qs=46VwSHQt9xVWoyRPllv4nQ%3D%3D

author: TimFox
author_rank: Super Contributor
timestamp: April 25, 2023, 05:58:19 pm
content: You could also connect the two windings in series: one connection will work when the two fluxes add, and the other will not work when the flux from the two windings cancels out.However, it is simpler and probably better to use a single-winding inductor.

author: hurricanehenry
author_rank: Regular Contributor
timestamp: April 25, 2023, 06:12:14 pm
content: Thanks all for your comments and suggestions.I will try all the suggested variants.Also, I managed to find a couple of 1 mH inductors amongst my components. So I will connect these in parallel to get 0.5 mH and try the experiment.Then I will try it again using the variants on the 4 leads choke.I also found a video recapping how to measure inductance: