I don't see such a post in this thread.shabtek said:NYD advised not making a tapped rather separate inductor for each value,fwiw.
This shouldn't be an issue. When hand winding it is necessary to adjust the final value, which implies overwinding, measuring, cutting measuring, cutting until final value is achieved with desired precision. It's very tedious, since the core must be fully reassembled before measuring, but it's doable.shabtek said:I agree abbey, I was browsing through threads with 'amidon' in them --think dave may have been referring to matching values. it is not easy to get matching values and taps on the same core when winding by hand. tension variations of successive windings can change things
I'm not sure what you mean by that...also in theory the core can only be optimized for 1 value.
It does, but I'm not sure these cores are suitable for audio inductors. They seem to be spec'd only for smps and converters.let's see if this attachment works
I am speculating why NYD suggested 1 inductor per frequency.abbey road d enfer said:I'm not sure what you mean by that...
I've used them (amidon 77) for 1H and 100uH values in audio eqs (api copy) with success.abbey road d enfer said:It does, but I'm not sure these cores are suitable for audio inductors. They seem to be spec'd only for smps and converters.
By using e.g. 4 separate inductors or one with 4 taps, the net workload is about the same...shabtek said:I am speculating why NYD suggested 1 inductor per frequency.
I know tapped works fine in practice, hitting a given L and R value would be simplified by not having taps.
TBH I've never used anything else than RM types. RM8 is quite small. I used mainly RM10 and RM14.do you have suggestion for other core?
I am curious what the difference is to rm8 or what carnhill uses
Well, it starts with the values you need. Then we must figure what value for Al is usable, and select the wire gauge, check the resulting winding fits in the bobbin and that teh DC resistance is adequate.HI Abbey Road,
if you have a moment, could you help me choose a suitable version of the Rm8 core for a neve style eq inductor?
is this good enough? They have other N types and with different inductance factors. Is there a particular version I should choose? I don't understand the difference however I can wind the buggers.
Michael de A
Indeed. But an additional problem is the large tolerance (about 30% IIRC) which makes reaching the correct value quite a tedious job, even for one-offs.I like the ungapped T38 ferrite material for audio - AL is 12500 nH for the RM8 - https://www.elfadistrelec.dk/da/rm8-core-set-t38-pk-par-stk-epcos-b65811j0000y038/p/15865208 - requiring a more feasible 895 turns for 10H
Depending on the actual signal levels and frequencies acting on the (specially large-inductance inductor) cores, you may easily get well into core saturation.
For these two reasons, I have always preferred larger gapped cores. For 10H, I used RM10 or RM14 cores.Which may or may not be a problem - but for low frequencies I usually prefer much beefier core sizes