Making 7H or 10H inductors

[muffy1975]

Hi fellow groupies,

i've searched the forum but have found nothing on this.....

I'm trying to make a 7H or 10H inductor with an RM cores.

Do you know or think an RM12 core with 0.22swg will allow me to achieve this value?

The eq would be either the redd or helios eq which both use this large value inductor for the bass boost.

regards

Michael

 

[ding]

I've been slightly looking into this lately since I would like to wind my own and will be doing Ian's Helios. I found this thread and in reply #9 there is a worksheet that is pretty good.

http://groupdiy.com/index.php?topic=55373.0

I'm not sure if it would help with RM12 but check it out.

 

[bruno2000]

I have wound 10H inductord on RM10 cores, but it's been so long ago that I am not sure of the details.  I believe I used #36 wire.  BTW, I usually make up my "test" coil of 500 turns rather than 100.  I test and number each set of cores (for AL value), plug the values into a spreadsheet that calculates the number of turns for each specific set of cores.  I most always get tolerances of about 2%.  YMMV.
Best,
Bruno2000

 

[abbey road d enfer]

Hi fellow groupies,

i've searched the forum but have found nothing on this.....

I'm trying to make a 7H or 10H inductor with an RM cores.

Do you know or think an RM12 core with 0.22swg will allow me to achieve this value?

The eq would be either the redd or helios eq which both use this large value inductor for the bass boost.

regards

Michael

RM12 Al 1000 calculates at 3160 turns for 10H.
The cross area An is 73 mm², which allows a square section of 0.023 mm², which in turn calculates as 0.15 mm diameter.
Average turn length is about 60 mm, for a total length of about 190m, resulting in ca. 130 ohm DCr.
It is possible to use ungapped cores, with much higher Al, resulting in 3-6 times less turns, but the tolerance on ungapped cores is really questionable (-20/+30%); in comparison the gapped Al1000 has 5% tolerance. Ungapped cores often are responsible for higher THD.