On 8/20/2019 11:11 AM, Tim Williams wrote:> "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 >Man, what time did I write the above? What I meant to say was, I had a BOG before and used a bedds that had a Q of 1 or 2. so if I could get 20 it would be better. It's for a receive only antenna, so microwatts, maybe milliwatts. 500kHz to 4 MHz. Mikek Another possible solution, Is there a combination of L's and Cs the would approximate such an L reduction over frequency?
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 8/20/2019 9:11 AM, Clive Arthur wrote:> 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, Mikek > > OK, so the DC is from a high impedance current source I guess.I don't have a good understanding of the (I'm guessing) loading that power supply connection will cause, but I did have the thought of a high voltage dc supply and a big series resistor. 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. > > CheersI'll look for that program. Does a reduction in area requiring more turns for the same inductance then saturate at a lower current? (because more turns) Thanks, Mikek
Reply by ●August 20, 20192019-08-20
On 8/20/2019 9:15 AM, Lasse Langwadt Christensen 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 range >Well that was my next question, will the big inductors isolate the coil and preserve the Q even though dc loaded? I think I attached a preliminary drawing but here it is again.> https://www.dropbox.com/s/f0l1kneuh0izqds/BOG%2C%20with%20variable%20inductor.jpg?dl=0Thanks, Mikek
Reply by ●August 20, 20192019-08-20
On 8/20/2019 10:05 AM, jlarkin@highlandsniptechnology.com wrote:> 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 range > > One 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. >Would that require running a second control wire parallel to the BOG, if so, probably not a good solution. Remember there are at least nine spread out over the 250ft wire. Thanks, Mikek
Reply by ●August 20, 20192019-08-20
On 8/20/2019 11:28 AM, Phil Hobbs wrote:> 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. >> >> Cheers > > One 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 > >Can you explain physically how that would look? My only experience with half turns is, we put a 4-1/2 turn inductor in a medium power circuit. The coil over heated, 4 turns were fine, 5 turns were fine, we never did a half turn inductor again. OH wait you only mean a single half turn as we did above, so if I need 12 turns make it 12-1/2 turns. Is that correct? Any way to do 1/2 turn on a toroid? Thanks, Mikek
Reply by ●August 20, 20192019-08-20
On 8/20/2019 11:41 AM, legg wrote:> 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, Mikek > A 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 >As state previously, My question was not ask well, I only want one winding with both ac and the dc to saturate it. Thanks, Mikek
Reply by ●August 20, 20192019-08-20
On 8/20/2019 9:15 AM, Lasse Langwadt Christensen 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 range >I'm looking t 2.5mH inductors, What spec am I looking for that says it can have 500ma of dc current and still be 2.5mH, ie it's not saturated. Mikek
Reply by ●August 20, 20192019-08-20
On 8/20/2019 7:51 PM, amdx wrote:> On 8/20/2019 9:15 AM, Lasse Langwadt Christensen 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 range >> > > I'm looking t 2.5mH inductors, What spec am I looking for that says it > can have 500ma of dc current and still be 2.5mH, ie it's not saturated. > MikekNever mind went to Digikey, more data than Amazon. :-)
Reply by ●August 20, 20192019-08-20
"amdx" <nojunk@knology.net> wrote in message news:qjhbo9$uq0$1@dont-email.me...> Man, what time did I write the above? > What I meant to say was, > I had a BOG before and used a bedds that had a Q of 1 or 2. > so if I could get 20 it would be better.I still don't know what you're writing. It ain't English... Well, "bog" aside. But that means something different in English English. ;-)> > It's for a receive only antenna, so microwatts, maybe milliwatts. > 500kHz to 4 MHz.What about just low noise JFETs? It's not like you need any antenna gain in those bands.> Another possible solution, > Is there a combination of L's and Cs the would approximate such an L > reduction over frequency?Sure. But not just L and C, R is required. Necessarily has a very low Q (from Kramers-Kronig relations). Ferrite beads for example. Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
Reply by ●August 21, 20192019-08-21
On 8/20/2019 12:47 PM, amdx wrote:> On 8/20/2019 11:11 AM, Tim Williams wrote: >> "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 >> > �Man, what time did I write the above? > What I meant to say was, > I had a BOG before and used a bedds that had a Q of 1 or 2. > � so if I could get 20 it would be better. > > It's for a receive only antenna, so microwatts, maybe milliwatts. > 500kHz to 4 MHz. > > �������������������������������� Mikek > > �Another possible solution, > �Is there a combination of L's and Cs the would approximate such an L > reduction over frequency? >One of those times, I could see you posted but nothing in the post, so I went to google groups. >> Man, what time did I write the above? >> What I meant to say was, >> I had a BOG before and used a bedds that had a Q of 1 or 2. >> so if I could get 20 it would be better. >I still don't know what you're writing. It ain't English... >Well, "bog" aside. But that means something different in English >English. >;-) I'll try to get a good nights sleep tonight! BOG = Beverage On Ground bedds was supposed to be beads/sleeves which were actually a #73 binocular core that I only used one hole of. I just passed the antenna wire through it. About 24 ohms R and 42 ohm XL at 1MHz. >> >> It's for a receive only antenna, so microwatts, maybe milliwatts. >> 500kHz to 4 MHz. >What about just low noise JFETs? It's not like you need any antenna >gain in >those bands. Well, maybe, but usually the receive has enough gain, the bog signal is down, maybe -25dbi to -40dbi. But that is not the problem, by adjusting characteristics with frequency you can narrow the beam width and increase the front to back ratio. btw, I do have a high input impedance FET follower with low output impedance, no gain but you do unload the antenna so get 3db. I'll be trying that. >> Another possible solution, >> Is there a combination of L's and Cs the would approximate such an L >> reduction over frequency? >Sure. But not just L and C, R is required. Necessarily has a very low >Q >(from Kramers-Kronig relations). Ferrite beads for example. Yes, that surprised me very much, but with low inductive reactance values and losses in the ferrite, you get Q's of 1 or 2. I tried and tried to get the meter on my Q meter to move, could not find any resonance, so pulled out an inductance meter and used that. Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
