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coil help Answered

Hi Guys i hope you can help me im in the process of saucing all the part i need for my nixie clock project but the project requires a specific coil please see link: http://za.mouser.com/ProductDetail/Fastron/MESC-101M-00/?qs=%2fha2pyFadujay2cCU0hcuafg8EcJuL7YYs%2fD4YaFoKs%3d

the problem is i cant find this locally is there an alternative i can use ?
any help will be appreciated. thanks

ps the project is the ArduiNIX :


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Jack A Lopez
Jack A Lopez

Best Answer 5 years ago

The text in Step 3 of that 'ible,


suggests this inductor, this coil, is part of a boost converter,


So I think for a substitution, for this part, in the role it has to perform, you want three things: Inductance close to the same spec (100 microhenry), and DC resistance less than or equal to that the spec'd part (780 milliohm = 0.780 ohm), and saturation current greater than or equal to the spec for... Dang! I can't find a specification for saturation current.

I dunno. More knowledge about the circuit would be helpful.

By the way, I don't know if you noticed or not, but the author of that instructable is selling his project in kit form, here,


Also I think buying the kit would probably be the easiest way to actually build this shield. I mean, even if you have all the parts, you need to figure out how they all go together. Well actually, all the wiring information is in the traces on the unpopulated circuit board.

Do you have a copy of the circuit diagram for this? Has a diagram for this circuit been published?

Erm...wait. Maybe you bought the "board only" version, and that explains why you're hunting down parts individually. Maybe. If that's the case, then you should ask the author of that 'ible about workable substitutions for that inductor.

Actually the comments section, of that instructable,


would be a good place for your question, since the author, Slothfurnace, could answer it, and everyone could benefit from the reply.


Answer 5 years ago

Hi thanks for the reply im actually getting the pcb printed locally as on the website they supply the .pcb files also it takes forever for stuff to ship to RSA , I lucky found a local supplier for the nixie tubes ,the only thing i have ordered are the drivers. i have sent a mail from their site but still waiting a response i have however found this coil any idea if this is a good substitute ?


Jack A Lopez
Jack A Lopez

Answer 5 years ago

I am guessing that one will work. Its data sheet,

says it has a saturation current of 0.70 A.

Right. So what does that mean? Or why is Isat important?

Well, the way a boost converter works is you have this inductor L, and you can put energy into the inductor at a low voltage, and then take energy out of the inductor at a higher voltage.

Ideally the energy stored in an inductor is U=0.5*L*I^2, but for an inductor that saturates, this equation is really only good for current less than the saturation current, i.e. for I< Isat.

I mean if I were designing a boost converter, I would want to to design it so Imin<Imax<Isat. This is why I am kind of expecting Isat to be an important number for this inductor.

So how big does Imax have to be? Well, I'm sure it depends on how much current, Ioutavg, is needed by the nixie tubes.

To make a long story short, I think the absolute best you could do for {Vin=9V, Vout=180V, D = 0.95, Imax=0.7A, Imin=0, Eff=1},
Ioutavg = 0.0166 A =16.6 mA,

and that's sort of an upper limit for output current. I'm not sure how much current the nixie array actually wants. If the answer is like 2mA (time-averaged), then that is good news, since its small compared to 16.6 mA. If the nixie array wants like 20 mA, then I dunno, there might be problems.

BTW, this upper limit of 16.6 mA is based on the crude equations that follow:

Voltage Gain and Duty Cycle for Continuous Mode
Vout/Vin = (180V)/(9V) = 20 = 1/(1-D)
D = 0.95

Average Input Current
Iinavg = D*0.5*(Imax-Imin)

Conservation of Energy
Pout = Eff*Pin
(Ioutavg*Vout) = Eff*(Iinavg*Vin)

Average Output Current
Ioutavg = (Vin/Vout)*Eff*(D*0.5*(Imax-Imin))


Answer 5 years ago

Thanks for all your help, you are very informative and helpful, il give it a try and see what happens


Josehf Murchison
Josehf Murchison

5 years ago

Old computer, DVD player, Look around you should be able to find a 100.

It's marking should be 101M