Measuring an inductance

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Wendy

Joined Mar 24, 2008
23,457
One long while ago I bought a capacitance/ inductance meter. I had a thought how to do this for the DIY user. It starts off with this premise:

temp.png

does anyone see any obvious flaws with this idea?
I will come up with other ideas for this project and post them here.
 
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tautech

Joined Oct 8, 2019
400
After borrowing a LCR bridge decades ago and about to venture into SMD I said to hell with this big old gear and got SMD smart tweezers and advise anyone to do the same.
There are now many types available of varying capability and after recently upgrading to a newer version I would highly recommend these for all passive component testing:
https://www.aliexpress.com/item/1005004239869204.html?
Select 3rd image that includes the test PCB populated with precision components.
 

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Wendy

Joined Mar 24, 2008
23,457
Talk about bad smell, the above design stinks. It would need at least 10Khz to give a decent resolution. Leaving the counter in the dust.
 

jjw

Joined Dec 24, 2013
823
One long while ago I bought a capacitance/ inductance meter. I had a thought how to do this for the DIY user. It starts off with this premise:


does anyone see any obvious flaws with this idea?
I will come up with other ideas for this project and post them here.
The time constant is L/R.
If L=1uH and R=1kohm, t~1ns
 

BobTPH

Joined Jun 5, 2013
9,124
A while back I came across a very simple circuit with a bistable multivibrator, where the feedback on one side was the inductor. The inductance is inversely proportional to the frequency of oscillation. Same idea.
 

Thread Starter

Wendy

Joined Mar 24, 2008
23,457
A while back I came across a very simple circuit with a bistable multivibrator, where the feedback on one side was the inductor. The inductance is inversely proportional to the frequency of oscillation. Same idea.
any chance you could get a schematic?
 

Ian0

Joined Aug 7, 2020
10,001
Not absolutely sure this will work, but I do know you like 555s. I think that if you take the astable circuit with the resistor from output to pins 2 and 6, replace the resistor with the inductor, replace the capacitor with a resistor, it should oscillate at a frequency proportional to R/L.
 

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Wendy

Joined Mar 24, 2008
23,457
The thing that is bending my brain I am having trouble thinking in terms of current instead of voltage. I have gone down this rabbit hole before as evidenced by some of my really older threads. I am convinced in my head there is some way to do this simply with a minimum of components.
 
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Thread Starter

Wendy

Joined Mar 24, 2008
23,457
I'm not sure how good it is but Amazon has a LC meter that is very affordable, I have a much older velleman model, not sure if they still sell it. I'm dropping this thread, I would still like to know how they do it.

LC meter.png
 
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