Solid State Inductance

J

JonDoeEngineer

Guest
I recall once seeing a fully solid state circuit that uses capacitors,
resistors and a transistor to "mimic" the effects of an inductor. I
can't seem to find it now. Can anyone point me in the right direction?
 
"JonDoeEngineer" <jondoeengineer@hotmail.com> wrote in message
news:1104984527.348732.202250@c13g2000cwb.googlegroups.com...
I recall once seeing a fully solid state circuit that uses capacitors,
resistors and a transistor to "mimic" the effects of an inductor. I
can't seem to find it now. Can anyone point me in the right direction?
Click to expand...
Google for "gyrator"
 
JonDoeEngineer wrote:
I recall once seeing a fully solid state circuit that uses capacitors,
resistors and a transistor to "mimic" the effects of an inductor. I
can't seem to find it now. Can anyone point me in the right direction?
Click to expand...
Simulated inductance that is grounded on one end is easiest, I think.

http://www.maxim-ic.com/appnotes.cfm/appnote_number/98
http://www.maxim-ic.com/appnotes.cfm/appnote_number/138
http://www.s2.chalmers.se/graduate/courses/analogVLSI/doc/lecture6.pdf
http://www.kemt.fei.tuke.sk/predmety/KEMT350_EP/_materialy/ch029.pdf


--
John Popelish
 
On 5 Jan 2005 20:08:47 -0800, "JonDoeEngineer"
<jondoeengineer@hotmail.com> wrote:

I recall once seeing a fully solid state circuit that uses capacitors,
resistors and a transistor to "mimic" the effects of an inductor. I
can't seem to find it now. Can anyone point me in the right direction?
Click to expand...
See the various Gyrator-based filters on the S.E.D/Schematics page of
my website.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
On Wed, 05 Jan 2005 23:43:34 -0500, John Popelish <jpopelish@rica.net>
wrote:

JonDoeEngineer wrote:

I recall once seeing a fully solid state circuit that uses capacitors,
resistors and a transistor to "mimic" the effects of an inductor. I
can't seem to find it now. Can anyone point me in the right direction?

Simulated inductance that is grounded on one end is easiest, I think.
Click to expand...
Why would anyone bother? Is there some obscure advantage with it over
conventional coils?
--

"What is now proved was once only imagin'd." - William Blake, 1793.
 
Why would anyone bother? Is there some obscure advantage with it over
conventional coils?
--
===============================
Click to expand...

A conventional hundred henry coil weighs several pounds, is bigger than the
printed circuit board, and has a terrible Q.
 
I read in sci.electronics.design that Reg Edwards
<g4fgq.regp@ZZZbtinternet.com> wrote (in <crka0i$44f$1@titan.btinternet.
com>) about 'Solid State Inductance', on Thu, 6 Jan 2005:
Why would anyone bother? Is there some obscure advantage with it over
conventional coils?
--
===============================

A conventional hundred henry coil weighs several pounds, is bigger than the
printed circuit board, and has a terrible Q.


Get some decent Mumetal cores. 10kH in about a 2 inch cube, with a
Click to expand...
laminated core. More with a toroid. Q indeed was not promising at 1 kHz,
but this operated at 10 to 20 kHz.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
"john jardine" <john@jjdesigns.fsnet.co.uk> wrote in message
news:crkhie$722$1@news6.svr.pol.co.uk...
On 5 Jan 2005 20:08:47 -0800, "JonDoeEngineer"
jondoeengineer@hotmail.com> wrote:

I recall once seeing a fully solid state circuit that uses capacitors,
resistors and a transistor to "mimic" the effects of an inductor. I
can't seem to find it now. Can anyone point me in the right direction?
Click to expand...
isn't copper solid state? Everytime I see this tread that pops into my
mind.
Pat
 
The name of the circuit to make an equ inductances is called a "Gyrator".

A study was done by Roger Rerden (spelling) on Gyrators.


One advantange is to replace inductors in LC filter designs.


A tranistor common emitter circuit with the capacitor across the base
emitter will simulate an inductor at the tied collector end.

As freq goes up the cap starves the base current turning the transistor more
off.

This is obvious as the common emitter inverts signals (180deg) phase shift.

JG

"Ben Bradley" <ben_nospam_bradley@mindspring.com> wrote in message
news:56rut0p06f8854j95p9ejhl3be0csqijpm@4ax.com...
On Thu, 06 Jan 2005 17:29:18 +0000, Paul Burridge
pb@notthisbit.osiris1.co.uk> wrote:

On Wed, 05 Jan 2005 23:43:34 -0500, John Popelish <jpopelish@rica.net
wrote:

JonDoeEngineer wrote:

I recall once seeing a fully solid state circuit that uses capacitors,
resistors and a transistor to "mimic" the effects of an inductor. I
can't seem to find it now. Can anyone point me in the right
direction?

Simulated inductance that is grounded on one end is easiest, I think.

Why would anyone bother? Is there some obscure advantage with it over
conventional coils?

It's much more immune to external signals induced by external
varying magnetic fields. Traditional coils may require mu-metal
shielding to get near as much immunity, which usually costs a lot of
money, and there's nothing obscure about money.
There are probably a few more obscure things such as hysteresis,
core saturation and inducing signals into nearby coils that an
"electronic inductor" doesn't do. OTOH, real inductors don't need a
separate DC power supply to have inductance.
Like most anything in engineering, there are many trade-offs, and
which one is best depends on the application. There are still plenty
of applications where a "real" inductor is the best or only solution.

-----
http://mindspring.com/~benbradley
Click to expand...
 
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