On 20/08/2019 01:53, amdx wrote:> I'd like to have a Variable 100uh inductor, that is controlled to full > saturation with dc through the 100uh coil. > I see some two winding coils, but the dc control winding has huge > inductance. Working range 500kHz to 4MHz. > Is this possible? > > Thanks for your thoughts, MikekSome RM cores and pot cores have a central hole through which you could wind your 100uH, and the DC winding goes on the bobbin... https://uk.farnell.com/ferroxcube/rm10-i-3c95/ferrite-core-rm-i-3c95/dp/2103458?st=rm%20core ...this is a 5.5uH core so approx 4 turns for 100uH if it were wound on the bobbin, I don't know how many if wound through the hole, but I'd guess it would be similar. I'd try to grind the hole edges to take off the sharp edge if possible. Cheers -- Clive
How to design an Interesting inductor
Started by ●August 19, 2019
Reply by ●August 20, 20192019-08-20
Reply by ●August 20, 20192019-08-20
On Tue, 20 Aug 2019 03:33:18 -0500, amdx <nojunk@knology.net> wrote:>On 8/19/2019 9:49 PM, Tim Williams wrote: >> Why, how fast do you need to control it? >> >> Tim >> > > Slow, in seconds. > MikekHow about a mechanical variometer. Make a bar that fits into the coil. One end of the bar is made of some ferrite material the other of aluminum. Connect it to a screw and run it with a stepper motor.
Reply by ●August 20, 20192019-08-20
On 8/20/2019 3:53 AM, upsidedown@downunder.com wrote:> On Tue, 20 Aug 2019 03:33:18 -0500, amdx <nojunk@knology.net> wrote: > >> On 8/19/2019 9:49 PM, Tim Williams wrote: >>> Why, how fast do you need to control it? >>> >>> Tim >>> >> >> Slow, in seconds. >> Mikek > > How about a mechanical variometer. > > Make a bar that fits into the coil. One end of the bar is made of some > ferrite material the other of aluminum. Connect it to a screw and run > it with a stepper motor. >See later posts Thanks, Mikek
Reply by ●August 20, 20192019-08-20
On 8/20/2019 3:41 AM, Clive Arthur wrote:> On 20/08/2019 01:53, amdx wrote: >> I'd like to have a Variable 100uh inductor, that is controlled to full >> saturation with dc through the 100uh coil. >> I see some two winding coils, but the dc control winding has huge >> inductance. Working range 500kHz to 4MHz. >> Is this possible? >> >> Thanks for your thoughts, Mikek > > Some RM cores and pot cores have a central hole through which you could > wind your 100uH, and the DC winding goes on the bobbin... > > https://uk.farnell.com/ferroxcube/rm10-i-3c95/ferrite-core-rm-i-3c95/dp/2103458?st=rm%20core > > > ...this is a 5.5uH core so approx 4 turns for 100uH if it were wound on > the bobbin, I don't know how many if wound through the hole, but I'd > guess it would be similar. I'd try to grind the hole edges to take off > the sharp edge if possible. > > CheersSorry, responses have made it clear I didn't ask my question well. I only want one winding of 100uh, that winding will both the ac and the dc. Thanks, Mikek
Reply by ●August 20, 20192019-08-20
On 20/08/2019 14:57, amdx wrote:> On 8/20/2019 3:41 AM, Clive Arthur wrote: >> On 20/08/2019 01:53, amdx wrote: >>> I'd like to have a Variable 100uh inductor, that is controlled to >>> full saturation with dc through the 100uh coil. >>> I see some two winding coils, but the dc control winding has huge >>> inductance. Working range 500kHz to 4MHz. >>> Is this possible? >>> >>> Thanks for your thoughts, Mikek >> >> Some RM cores and pot cores have a central hole through which you >> could wind your 100uH, and the DC winding goes on the bobbin... >> >> https://uk.farnell.com/ferroxcube/rm10-i-3c95/ferrite-core-rm-i-3c95/dp/2103458?st=rm%20core >> >> >> ...this is a 5.5uH core so approx 4 turns for 100uH if it were wound >> on the bobbin, I don't know how many if wound through the hole, but >> I'd guess it would be similar. I'd try to grind the hole edges to >> take off the sharp edge if possible. >> >> Cheers > > Sorry, responses have made it clear I didn't ask my question well. > I only want one winding of 100uh, that winding will both the ac and > the dc. > > Thanks, MikekOK, so the DC is from a high impedance current source I guess. As an indication, a 100uH inductor on an RM4 3C92 core 722nH/T^2 will be 12 turns and saturate at around 500mA. There's a program, ferroxcube.exe entitled Ferroxcube SFDT 2010 which is handy. Cheers -- Clive
Reply by ●August 20, 20192019-08-20
tirsdag den 20. august 2019 kl. 15.57.08 UTC+2 skrev amdx:> On 8/20/2019 3:41 AM, Clive Arthur wrote: > > On 20/08/2019 01:53, amdx wrote: > >> I'd like to have a Variable 100uh inductor, that is controlled to full > >> saturation with dc through the 100uh coil. > >> I see some two winding coils, but the dc control winding has huge > >> inductance. Working range 500kHz to 4MHz. > >> Is this possible? > >> > >> Thanks for your thoughts, Mikek > > > > Some RM cores and pot cores have a central hole through which you could > > wind your 100uH, and the DC winding goes on the bobbin... > > > > https://uk.farnell.com/ferroxcube/rm10-i-3c95/ferrite-core-rm-i-3c95/dp/2103458?st=rm%20core > > > > > > ...this is a 5.5uH core so approx 4 turns for 100uH if it were wound on > > the bobbin, I don't know how many if wound through the hole, but I'd > > guess it would be similar. I'd try to grind the hole edges to take off > > the sharp edge if possible. > > > > Cheers > > Sorry, responses have made it clear I didn't ask my question well. > I only want one winding of 100uh, that winding will both the ac and > the dc. > > Thanks, Mikekhttps://www.frostburg.edu/personal/latta/ee/qsk5/pindiodes/spstswitch.jpg replace diode with your inductor and adjust values to match your freqency range
Reply by ●August 20, 20192019-08-20
On Tue, 20 Aug 2019 07:15:10 -0700 (PDT), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:>tirsdag den 20. august 2019 kl. 15.57.08 UTC+2 skrev amdx: >> On 8/20/2019 3:41 AM, Clive Arthur wrote: >> > On 20/08/2019 01:53, amdx wrote: >> >> I'd like to have a Variable 100uh inductor, that is controlled to full >> >> saturation with dc through the 100uh coil. >> >> ��I see some two winding coils, but the dc control winding has huge >> >> inductance. Working range 500kHz to 4MHz. >> >> ��Is this possible? >> >> >> >> ��������������� Thanks for your thoughts, Mikek >> > >> > Some RM cores and pot cores have a central hole through which you could >> > wind your 100uH, and the DC winding goes on the bobbin... >> > >> > https://uk.farnell.com/ferroxcube/rm10-i-3c95/ferrite-core-rm-i-3c95/dp/2103458?st=rm%20core >> > >> > >> > ...this is a 5.5uH core so approx 4 turns for 100uH if it were wound on >> > the bobbin, I don't know how many if wound through the hole, but I'd >> > guess it would be similar.� I'd try to grind the hole edges to take off >> > the sharp edge if possible. >> > >> > Cheers >> >> Sorry, responses have made it clear I didn't ask my question well. >> I only want one winding of 100uh, that winding will both the ac and >> the dc. >> >> Thanks, Mikek > >https://www.frostburg.edu/personal/latta/ee/qsk5/pindiodes/spstswitch.jpg > >replace diode with your inductor and adjust values to match your freqency rangeOne could also use PIN diodes, or relays, or latching relays to switch taps on an air-core inductor, in interesting combinations. Q would be high.
Reply by ●August 20, 20192019-08-20
"amdx" <nojunk@knology.net> wrote in message news:qjgbfo$1la$1@dont-email.me...> In previous responses I gave the proposed use is for a > "Beverage on Ground" antenna. > I had a GOG before and used a beds that had a Q of 1 or 2. > so if I could get 20 it would be better.What power level? Frequency range? Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
Reply by ●August 20, 20192019-08-20
On 8/20/19 4:41 AM, Clive Arthur wrote:> On 20/08/2019 01:53, amdx wrote: >> I'd like to have a Variable 100uh inductor, that is controlled to full >> saturation with dc through the 100uh coil. >> I see some two winding coils, but the dc control winding has huge >> inductance. Working range 500kHz to 4MHz. >> Is this possible? >> >> Thanks for your thoughts, Mikek > > Some RM cores and pot cores have a central hole through which you could > wind your 100uH, and the DC winding goes on the bobbin... > > https://uk.farnell.com/ferroxcube/rm10-i-3c95/ferrite-core-rm-i-3c95/dp/2103458?st=rm%20core > > > ...this is a 5.5uH core so approx 4 turns for 100uH if it were wound on > the bobbin, I don't know how many if wound through the hole, but I'd > guess it would be similar. I'd try to grind the hole edges to take off > the sharp edge if possible. > > CheersOne minor tweak to that idea is to run an odd number of half-turns on the bobbin, and use a high-mu pot core with an adjustable centre gap. The extra half-turn will generate a large field going round the outside of the core (avoiding the post) and so will saturate it fairly readily. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●August 20, 20192019-08-20
On Mon, 19 Aug 2019 19:53:28 -0500, amdx <nojunk@knology.net> wrote:>I'd like to have a Variable 100uh inductor, that is controlled to full >saturation with dc through the 100uh coil. > I see some two winding coils, but the dc control winding has huge >inductance. Working range 500kHz to 4MHz. > Is this possible? > > Thanks for your thoughts, MikekA cpnventional current-controlled inductor has two magnetic paths that are configured to carry antiphase windings, with the third 'inductor winding sharing both. The control windings' AC flux, from the third winding, cancels out. You can do this with an e-core (control windings on outer arms), two toroids (each with control winding - sandwitched to support single 'inductor' winding around both) or solenoids (two solenoid cores support control windings, 'inductor' wound around both.). RL
