What is uH in a circuit diagram?

[FireAce]

Hey fellows, need a hand on this circuit here with a LM2576T-ADJ switching regulator

**broken link removed**

There is an item in the diagram called uH and I cant find anything on Google as to what this pertains.

I want to be able to adjust the output voltage on the fly, preferably with a pot, not sure if thats what its calling for.

 

[Reloadron]

L1 is an Inductor with a value of 150 uH (u = micro and H = Henry) so a 150 micro Henry inductor.

NOTE: 150μH/min. 3A choke coil and toroidal coil. It is rated for 3 amps of current!

Also, read the data sheet and note the variations of the chip. See page 19 Figure 15 as it is along the lines of what you seem to want.


Ron

 

[FireAce]

Thank you, I currently have the Regulator working, and using a 10k pot to adjust. Works very well, BUT, I did not install an inductor, I simply bypassed it with a wire. Not sure what the importance of this coil is. I do have some on misc circuit boards from junked electronics, how exactly is the best way to measure these?

 

[Gobbledok]

While it will probably work without it (well you have it working) it will not work very well.

An inductor is an intrinsic part of a SMPS, and without it the output will be terrible and similar to a PWM output.

If you're lucky your multimeter will have an inductor measurement position on it.

But hey just try one of the old coils you have laying around, can't make it any worse

 

[FireAce]

Thanks fellows. I will pick a nice fat one from old boards laying around the workbench. I'm not lucky today, it doesnt appear I have a uH option on my "cheaper" multimeter.

I have
200u
20u
200n
20n
2n

Dont reckon its the same thing though.

 

[Gobbledok]

...it doesnt appear I have a uH option on my "cheaper" multimeter.

I have
200u
20u
200n
20n
2n

Dont reckon its the same thing though.

That'd more than likely be capacitance. It should have a capacitor symbol on there too probably.

 

[crutschow]

Thank you, I currently have the Regulator working, and using a 10k pot to adjust. Works very well, BUT, I did not install an inductor, I simply bypassed it with a wire. Not sure what the importance of this coil is. ..............

Interesting way to build a circuit. Is there anything else on the circuit you didn't recognize and so didn't include?

 

[FireAce]

Yea, it was asking for a 16v ham sandwich, but I didnt have one.

Lol, I should explain, yes I had it working, but on a solder-less breadboard. When I get to soldering down the real thing all the parts will be there.

 

[FireAce]

on the other hand, it doesnt appear to be working. Sending 24v dc into the regulator, powering an LED, and it gets insanely hot. Hmmm

...FIXED

 

[crutschow]

It's amazing how a circuit will work correctly with all the proper parts.

 

[DerStrom8]

Most inductors have a color code or number code on it. If you know how to read resistance color bands (/numbers), then it's the same code. You should be able to find one close to what you're looking for.

 

[FireAce]

Yea, was extra parts that was causing it. Boo boo on my part