Forums

0.2MHz - 2MHz step up transformer

Started by Paul Jackson January 22, 2012
On Mon, 23 Jan 2012 00:03:14 -0800 (PST), Bill Sloman
<bill.sloman@ieee.org> wrote:

>You seem to live in a different universe from mine. > >-- >Bill Sloman, Nijmegen
Said the fake who doesn't actually do any electronics.
"Bill Sloman" <bill.sloman@ieee.org> wrote in message 
news:da93ccd8-dc66-49ad-89f9-d0c940fe9e83@t13g2000yqg.googlegroups.com...
> > Honestly, I can make a transformer with that kind of bandwidth by > > sitting > > on a ball of wire! Typically I see >10MHz from the gate drive > > transformers I carelessly put together, and ~50MHz with interleaving. > > How good are they at 200kHz?
As good as the core. Last one was somewhere around 10kHz to 10MHz. Likewise, a regular line transformer makes a poor audio output transformer since it might only get you 50Hz to 5kHz (typical of bobbin wound transformers), however, toroids typically go up to 200kHz with just single unit layer windings. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
On Mon, 23 Jan 2012 00:03:14 -0800 (PST), Bill Sloman
<bill.sloman@ieee.org> wrote:

>On Jan 23, 4:40&#2013266080;am, "Tim Williams" <tmoran...@charter.net> wrote: >> "BillSloman" <bill.slo...@ieee.org> wrote in message >> >> news:b109bfa8-5226-482a-a26d-f63d01d15ae3@f1g2000yqi.googlegroups.com... >> >> > > At 2 GHz, yes. But 2 MHz isn't especially fast. >> >> > It's a 10:1 bandwidth range. Ferrites that are good for 2MHz don't >> > have particularly high permeabilities, and lots of turns to make up >> > for the low permeability of the core tend to leave you with >> > inconveniently low self-resonance frequencies. >> >> If you were designing a power transformer, this might be the case. >> Typically NiZn ferrites are used, with Bmax ~ 0.3T and mu_r ~ 800, like >> Fair-Rite #43. &#2013266080;These might be usable close to Bsat for small >> transformers, but the core loss requires Bmax < 0.1T for most power >> applications. &#2013266080;Which is fine, since it doesn't take much core at 2MHz to >> achieve that. >> >> But signal applications under 1W are hardly the concern of core loss. > >10V into 50R is 2W. > >> Typically, a pulse transformer is wound on the highest permeability core >> possible (e.g., Ferroxcube 3E5, Magnetics 'W'), which accordingly has very >> high losses at high frequency (complex permeability is essentially >> imaginary), but still has greater total permeability up to several MHz >> than the HF material. &#2013266080;This means you can use simpler coil geometry, >> giving a higher SRF despite the higher inductance. &#2013266080;As a bonus, the SRF is >> dampened by the core losses at those frequencies. > >Typically pulse transformers are transmission line transformers wound >with a twisted pair transmission line, as I pointed out in my original >response - not a lot of the high frequency flux makes it into the >core. > >> > Do you want to design a suitable more-or-less conventional >> > transformer? I tried it once, and a transmission line transformer made >> > with twisted pair is what worked. >> >> Honestly, I can make a transformer with that kind of bandwidth by sitting >> on a ball of wire! &#2013266080;Typically I see >10MHz from the gate drive >> transformers I carelessly put together, and ~50MHz with interleaving. > >How good are they at 200kHz? > >>&#2013266080;If more than that is required, twisted pair gets involved. > >You seem to live in a different universe from mine.
Right. He actually does stuff. John
On Jan 22, 9:10=A0pm, pauljack...@thermalux.com (Paul Jackson) wrote:
> On Sun, 22 Jan 2012 17:04:58 -0800, Joerg <inva...@invalid.invalid> > wrote: > > >That buys about ten excellent lunches for two with two large Hefeweizens > >on tap at our Japanese restaurant. I prefer those lunches :-) > > Great. If I was there you could invite me to lunch and draw a design > on a Japanese napkin ... preferably before the beers. > > I can't really afford a Tek HV amp, and I only need a few hundred > volts. So I will keep creeping up the food chain, one start-up company > at a time. > > Paul
How many hundred's of Volts? There are some expensive Apex HV amps. (~$40-50) I was trolling the TI website a few weeks ago and they have some ~$10 amps that will do up to 100V. You could maybe run two of those in a bridge. George H.
On Jan 23, 1:23=A0pm, StickThatInYourPipeAndSmokeIt
<Zarathus...@thusspoke.org> wrote:
> On Mon, 23 Jan 2012 00:03:14 -0800 (PST), Bill Sloman > > <bill.slo...@ieee.org> wrote: > >You seem to live in a different universe from mine. > > =A0 Said the fake who doesn't actually do any electronics.
I'm not doing any electronics at the moment, but I did enough in the past to suggest that I'm not a fake. Search on scholar.google.com for "A W Sloman" and you'll find some real stuff - as well as a fair bit of stuff that never got to production, but would have worked if it had. -- Bill Sloman, Nijmegen
On Mon, 23 Jan 2012 00:36:40 GMT, pauljackson@thermalux.com (Paul
Jackson) wrote:

>On Sun, 22 Jan 2012 10:27:38 -0500, Jamie ><jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote: > > >> Being a function generator as the source, I think you better start >>thinking of HV amplifiers instead. A DC coupled one to be exact. >> > >What would be your opinion of these? > >http://www.piezomaster.com/ > >Paul
Here's my 400 volt amp, but it's fairly slow. ftp://jjlarkin.lmi.net/HVamp.JPG It would be cool to modify this to use low-voltage optocouplers cascoded with depletion mosfets. John
On Jan 23, 2:33=A0pm, "Tim Williams" <tmoran...@charter.net> wrote:
> "Bill Sloman" <bill.slo...@ieee.org> wrote in message > > news:da93ccd8-dc66-49ad-89f9-d0c940fe9e83@t13g2000yqg.googlegroups.com... > > > > Honestly, I can make a transformer with that kind of bandwidth by > > > sitting > > > on a ball of wire! Typically I see >10MHz from the gate drive > > > transformers I carelessly put together, and ~50MHz with interleaving. > > > How good are they at 200kHz? > > As good as the core. =A0Last one was somewhere around 10kHz to 10MHz. > > Likewise, a regular line transformer makes a poor audio output transforme=
r
> since it might only get you 50Hz to 5kHz (typical of bobbin wound > transformers), however, toroids typically go up to 200kHz with just singl=
e
> unit layer windings.
Single layer winding are nice - the parallel capacitance usually comes out of the order of a pF - but you don't get a lot of turns. -- Bill Sloman, Nijmegen
On Jan 23, 3:02=A0pm, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Mon, 23 Jan 2012 00:03:14 -0800 (PST), Bill Sloman > > > > > > > > > > <bill.slo...@ieee.org> wrote: > >On Jan 23, 4:40=A0am, "Tim Williams" <tmoran...@charter.net> wrote: > >> "BillSloman" <bill.slo...@ieee.org> wrote in message > > >>news:b109bfa8-5226-482a-a26d-f63d01d15ae3@f1g2000yqi.googlegroups.com..=
.
> > >> > > At 2 GHz, yes. But 2 MHz isn't especially fast. > > >> > It's a 10:1 bandwidth range. Ferrites that are good for 2MHz don't > >> > have particularly high permeabilities, and lots of turns to make up > >> > for the low permeability of the core tend to leave you with > >> > inconveniently low self-resonance frequencies. > > >> If you were designing a power transformer, this might be the case. > >> Typically NiZn ferrites are used, with Bmax ~ 0.3T and mu_r ~ 800, lik=
e
> >> Fair-Rite #43. =A0These might be usable close to Bsat for small > >> transformers, but the core loss requires Bmax < 0.1T for most power > >> applications. =A0Which is fine, since it doesn't take much core at 2MH=
z to
> >> achieve that. > > >> But signal applications under 1W are hardly the concern of core loss. > > >10V into 50R is 2W. > > >> Typically, a pulse transformer is wound on the highest permeability co=
re
> >> possible (e.g., Ferroxcube 3E5, Magnetics 'W'), which accordingly has =
very
> >> high losses at high frequency (complex permeability is essentially > >> imaginary), but still has greater total permeability up to several MHz > >> than the HF material. =A0This means you can use simpler coil geometry, > >> giving a higher SRF despite the higher inductance. =A0As a bonus, the =
SRF is
> >> dampened by the core losses at those frequencies. > > >Typically pulse transformers are transmission line transformers wound > >with a twisted pair transmission line, as I pointed out in my original > >response - not a lot of the high frequency flux makes it into the > >core. > > >> > Do you want to design a suitable more-or-less conventional > >> > transformer? I tried it once, and a transmission line transformer ma=
de
> >> > with twisted pair is what worked. > > >> Honestly, I can make a transformer with that kind of bandwidth by sitt=
ing
> >> on a ball of wire! =A0Typically I see >10MHz from the gate drive > >> transformers I carelessly put together, and ~50MHz with interleaving. > > >How good are they at 200kHz? > > >>=A0If more than that is required, twisted pair gets involved. > > >You seem to live in a different universe from mine. > > Right. He actually does stuff.
So did I. A few years ago. -- Bill Sloman, Nijmegen
On 1/22/2012 11:58 AM, John Larkin wrote:
> On Sun, 22 Jan 2012 08:01:45 -0600, amdx<amdx@knologynotthis.net> > wrote: > >> On 1/22/2012 6:05 AM, Paul Jackson wrote: >>> I am looking for an impedance matching transformer that will convert >>> the 50 Ohm output of my function generator and to a 1K Ohm resistive >>> load. >>> >>> That provides a 20x step-up as well, so with losses 10V yields maybe >>> 100V. >>> >>> Frequency range is anywhere between 200KHz to 2MHz. Required current, >>> up to 20mA. >>> >>> I would definitely prefer a ready-made transformer. Does anyone know >>> under what application heading one might be found? >>> >>> Paul Jackson >> >> If you want 20 ma at 100 volts, I don't think you generator will supply >> the power you need. >> If the generator supplies 10V into 50 ohms that is 20 ma. > > 200 mA, short-circuit current. > > John
Hi John, Oh, redid the math. You're right :-) Mikek
Paul Jackson wrote:
> On Sun, 22 Jan 2012 17:04:58 -0800, Joerg <invalid@invalid.invalid> > wrote: > >> That buys about ten excellent lunches for two with two large Hefeweizens >> on tap at our Japanese restaurant. I prefer those lunches :-) >> > > Great. If I was there you could invite me to lunch and draw a design > on a Japanese napkin ... preferably before the beers. > > I can't really afford a Tek HV amp, and I only need a few hundred > volts. So I will keep creeping up the food chain, one start-up company > at a time. >
But you do need at least some funding. If it has to be a fully linear scheme your best bet might be to create a really staunch "driver from hell" with just a few ohms output impedance and then use a multi-filar ferrite transformer to get the voltage up. There are HV-amplfiers but except for some super-expensive ones they are severely slew rate limited, won't help you here. If you could let us know some more details about what the objective is maybe there'd be other options. For example, if it's just pulsing a piezo or PZT5H with an adjustable amplitude that does not require a clean amplfier. -- Regards, Joerg http://www.analogconsultants.com/