Center Tapped and Regular Transformer

[Anand P. Paralkar]

On 27-08-2012 23:50, Anand P. Paralkar wrote:

Hi,

Could you please explain the following points regarding a center tapped
transformer (some questions apply to a non-center tapped "regular"
transformer as well):

a. Is the center tapped transformer wound differently than a non-center
tapped transformer? Or is it just a regular transformer for which the
center point of the secondary winding is "brought outside".

b. Considering the secondary voltage of a transformer is Vs, the two
terminals of the secondary are at +Vs/2 and -Vs/2. This implies a
voltage gradient across the secondary. The gradient passes through a
zero point which we "tap". What causes this voltage gradient?

c. Can we say that all the turns in the secondary winding of a
transformer have the same amount of flux passing through them at a given
instant or do they have a different amount of flux (with the flux
depending on the position of the turn)?

Thanks,
Anand

On 27-08-2012 23:50, Anand P. Paralkar wrote:

Hi,

Could you please explain the following points regarding a center tapped
transformer (some questions apply to a non-center tapped "regular"
transformer as well):

a. Is the center tapped transformer wound differently than a non-center
tapped transformer? Or is it just a regular transformer for which the
center point of the secondary winding is "brought outside".

b. Considering the secondary voltage of a transformer is Vs, the two
terminals of the secondary are at +Vs/2 and -Vs/2. This implies a
voltage gradient across the secondary. The gradient passes through a
zero point which we "tap". What causes this voltage gradient?

c. Can we say that all the turns in the secondary winding of a
transformer have the same amount of flux passing through them at a given
instant or do they have a different amount of flux (with the flux
depending on the position of the turn)?

Thanks,
Anand

Hi Everybody,

Firstly, thanks a lot for your detailed replies. Although this
started-off as a thread on my doubts on the transformer, this thread got
(unintentionally) drawn to another topic. One that I was planning to
post here anyway.

The reason I said that getting both - the positive and negative source
from a transformer without a center tap is difficult is that I tried
what a lot of people have recommended here. I built a circuit that had
the two diodes connected to the transformer secondary. One diode had
its anode while the other had its cathode connected to the transformer
secondary. The other end of these diodes were connected to a capacitor
each. These capacitors had a common point which we could call the ground.

I was surprised to find that this ground actually drifted! When I
measured the voltage across the ends of the capacitors (the end
connected to the diodes), the voltage measured was constant. However,
when I measured the voltage across the ground and the other end of the
capacitors, I saw that this voltage changed. So the V+ source and V-
source with respect to the ground was not constant!

I don't know the exact reason what causes this drift. But as a remedy,
I put a resistor in parallel to each of the capacitors. (P. E. Schoen
has posted this).

This stopped the ground from drifting but I don't think one could use
this solution in a practical circuit. A resistor in parallel at the
output of a voltage source will not hold up in case of a heavy load (low
load resistance).

That's why it seemed difficult.

There are ofcourse many other circuits that have been suggested here.
Thanks a ton gentlemen.

Thanks,
Anand

 

[Jamie]

Mark Zenier wrote:

In article <ns22h9-fmb.ln1@radagast.org>,
Dave Platt <dplatt@radagast.org> wrote:

In article <aa733fFdaqU1@mid.individual.net>,
Anand P. Paralkar <anand.paralkar@gnospammale.com> wrote:


I am sorry, I haven't been clear. We need to generate a positive *and*
negative voltage using the same transformer secondary without a center tap.

(I kind of started writing where I was irritated thinking about the
negative voltage.....)

http://www.bristolwatch.com/ele/power_supplies.htm shows how (see the
first example).

Basically: using a single-winding (non-centertapped) secondary, you
just ground one end of the secondary, and use two half-wave rectifying
circuits (one diode and one capacitor each) to generate the positive
and negative DC supplies.

I believe this approach will have somewhat higher amounts of ripple on
the unregulated DC supplies, because each capacitor will be recharged
during only half of the powerline cycle.


Another way, that I saw in an Elektor project, is to use a full wave
rectifier for the main supply and use two half wave doublers hooked
to each end of the secondary. (Or you could call it a capacitivly
coupled full wave rectifier).


------|(-----+----|<---------+----- V-?
| |
+-->|--gnd +--|(--gnd
|
+-->|--gnd |
| |
------|(-----+----|<---------+


Mark Zenier mzenier@eskimo.com
Googleproofaddress(account:mzenier provider:eskimo domain:com)

For some reason that circuit just does not look appealing..

Not knowing the application it is kind of hard to come up with the
proper solution however....


Transformer Bridge
+-+-++---+--------+
-. ,+--------+ A A + | |
)|( +--++ | --- | |
)|( +--+(-+ --- | |
-' '+--------+ A A + | |
+-+-++ + +------------------+
| .-. | | |
| | | | + |
R1, R2 100K | | | | |\| Ilimit |
| '-' +-+|-\ ___ |
| | | >--|___|-+---+ Commom
| +-----+|+/ GND
| .-. |/+
| | | |
| | | |
| '+' |
+---+--------+

Jamie

 

[Phil Hobbs]

On 08/31/2012 12:54 PM, Anand P. Paralkar wrote:

On 27-08-2012 23:50, Anand P. Paralkar wrote:
Hi,

Could you please explain the following points regarding a center tapped
transformer (some questions apply to a non-center tapped "regular"
transformer as well):

a. Is the center tapped transformer wound differently than a non-center
tapped transformer? Or is it just a regular transformer for which the
center point of the secondary winding is "brought outside".

b. Considering the secondary voltage of a transformer is Vs, the two
terminals of the secondary are at +Vs/2 and -Vs/2. This implies a
voltage gradient across the secondary. The gradient passes through a
zero point which we "tap". What causes this voltage gradient?

c. Can we say that all the turns in the secondary winding of a
transformer have the same amount of flux passing through them at a given
instant or do they have a different amount of flux (with the flux
depending on the position of the turn)?

Thanks,
Anand

On 27-08-2012 23:50, Anand P. Paralkar wrote:
Hi,

Could you please explain the following points regarding a center tapped
transformer (some questions apply to a non-center tapped "regular"
transformer as well):

a. Is the center tapped transformer wound differently than a non-center
tapped transformer? Or is it just a regular transformer for which the
center point of the secondary winding is "brought outside".

b. Considering the secondary voltage of a transformer is Vs, the two
terminals of the secondary are at +Vs/2 and -Vs/2. This implies a
voltage gradient across the secondary. The gradient passes through a
zero point which we "tap". What causes this voltage gradient?

c. Can we say that all the turns in the secondary winding of a
transformer have the same amount of flux passing through them at a given
instant or do they have a different amount of flux (with the flux
depending on the position of the turn)?

Thanks,
Anand

Hi Everybody,

Firstly, thanks a lot for your detailed replies. Although this
started-off as a thread on my doubts on the transformer, this thread got
(unintentionally) drawn to another topic. One that I was planning to
post here anyway.

The reason I said that getting both - the positive and negative source
from a transformer without a center tap is difficult is that I tried
what a lot of people have recommended here. I built a circuit that had
the two diodes connected to the transformer secondary. One diode had its
anode while the other had its cathode connected to the transformer
secondary. The other end of these diodes were connected to a capacitor
each. These capacitors had a common point which we could call the ground.

I was surprised to find that this ground actually drifted! When I
measured the voltage across the ends of the capacitors (the end
connected to the diodes), the voltage measured was constant. However,
when I measured the voltage across the ground and the other end of the
capacitors, I saw that this voltage changed. So the V+ source and V-
source with respect to the ground was not constant!

I don't know the exact reason what causes this drift. But as a remedy, I
put a resistor in parallel to each of the capacitors. (P. E. Schoen has
posted this).

This stopped the ground from drifting but I don't think one could use
this solution in a practical circuit. A resistor in parallel at the
output of a voltage source will not hold up in case of a heavy load (low
load resistance).

That's why it seemed difficult.

There are ofcourse many other circuits that have been suggested here.
Thanks a ton gentlemen.

Thanks,
Anand

You did connect the midpoint of the capacitor string to the other end of
the transformer secondary, right? Otherwise the whole thing won't do
much at all

Putting a bleed resistor on the caps reduces the supply impedance by
making the diodes conduct harder on each peak.


Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[John Fields]

On Fri, 31 Aug 2012 22:24:09 +0530, "Anand P. Paralkar"
<anand.paralkar@gnospammale.com> wrote:

On 27-08-2012 23:50, Anand P. Paralkar wrote:
Hi,

Could you please explain the following points regarding a center tapped
transformer (some questions apply to a non-center tapped "regular"
transformer as well):

a. Is the center tapped transformer wound differently than a non-center
tapped transformer? Or is it just a regular transformer for which the
center point of the secondary winding is "brought outside".

b. Considering the secondary voltage of a transformer is Vs, the two
terminals of the secondary are at +Vs/2 and -Vs/2. This implies a
voltage gradient across the secondary. The gradient passes through a
zero point which we "tap". What causes this voltage gradient?

c. Can we say that all the turns in the secondary winding of a
transformer have the same amount of flux passing through them at a given
instant or do they have a different amount of flux (with the flux
depending on the position of the turn)?

Thanks,
Anand

On 27-08-2012 23:50, Anand P. Paralkar wrote:
Hi,

Could you please explain the following points regarding a center tapped
transformer (some questions apply to a non-center tapped "regular"
transformer as well):

a. Is the center tapped transformer wound differently than a non-center
tapped transformer? Or is it just a regular transformer for which the
center point of the secondary winding is "brought outside".

b. Considering the secondary voltage of a transformer is Vs, the two
terminals of the secondary are at +Vs/2 and -Vs/2. This implies a
voltage gradient across the secondary. The gradient passes through a
zero point which we "tap". What causes this voltage gradient?

c. Can we say that all the turns in the secondary winding of a
transformer have the same amount of flux passing through them at a given
instant or do they have a different amount of flux (with the flux
depending on the position of the turn)?

Thanks,
Anand

Hi Everybody,

Firstly, thanks a lot for your detailed replies. Although this
started-off as a thread on my doubts on the transformer, this thread got
(unintentionally) drawn to another topic. One that I was planning to
post here anyway.

The reason I said that getting both - the positive and negative source
from a transformer without a center tap is difficult is that I tried
what a lot of people have recommended here. I built a circuit that had
the two diodes connected to the transformer secondary. One diode had
its anode while the other had its cathode connected to the transformer
secondary. The other end of these diodes were connected to a capacitor
each. These capacitors had a common point which we could call the ground.

I was surprised to find that this ground actually drifted! When I
measured the voltage across the ends of the capacitors (the end
connected to the diodes), the voltage measured was constant. However,
when I measured the voltage across the ground and the other end of the
capacitors, I saw that this voltage changed. So the V+ source and V-
source with respect to the ground was not constant!

I don't know the exact reason what causes this drift. But as a remedy,
I put a resistor in parallel to each of the capacitors. (P. E. Schoen
has posted this).

This stopped the ground from drifting but I don't think one could use
this solution in a practical circuit. A resistor in parallel at the
output of a voltage source will not hold up in case of a heavy load (low
load resistance).

That's why it seemed difficult.

There are ofcourse many other circuits that have been suggested here.
Thanks a ton gentlemen.

---
As Phil Hobbs has posted, it sounds like your caps aren't connected to
the other end of the transformer.

Or you've made a wiring error...

Try this: (view using a fixed-pitch font)


AC>----+ +----+--[DIODE>]-------+---->DC+
| | | |
P||S +--[<DIODE]-+-----|---->DC-
R||E |- |+
I||C [BFC] [BFC]
| | | |
AC>----+ +----------------+-----+---->GND

--
JF

 

[John Robertson]

Anand P. Paralkar wrote:

On 27-08-2012 23:50, Anand P. Paralkar wrote:
Hi,

Could you please explain the following points regarding a center tapped
transformer (some questions apply to a non-center tapped "regular"
transformer as well):

a. Is the center tapped transformer wound differently than a non-center
tapped transformer? Or is it just a regular transformer for which the
center point of the secondary winding is "brought outside".

b. Considering the secondary voltage of a transformer is Vs, the two
terminals of the secondary are at +Vs/2 and -Vs/2. This implies a
voltage gradient across the secondary. The gradient passes through a
zero point which we "tap". What causes this voltage gradient?

c. Can we say that all the turns in the secondary winding of a
transformer have the same amount of flux passing through them at a given
instant or do they have a different amount of flux (with the flux
depending on the position of the turn)?

Thanks,
Anand

On 27-08-2012 23:50, Anand P. Paralkar wrote:
Hi,

Could you please explain the following points regarding a center tapped
transformer (some questions apply to a non-center tapped "regular"
transformer as well):

a. Is the center tapped transformer wound differently than a non-center
tapped transformer? Or is it just a regular transformer for which the
center point of the secondary winding is "brought outside".

b. Considering the secondary voltage of a transformer is Vs, the two
terminals of the secondary are at +Vs/2 and -Vs/2. This implies a
voltage gradient across the secondary. The gradient passes through a
zero point which we "tap". What causes this voltage gradient?

c. Can we say that all the turns in the secondary winding of a
transformer have the same amount of flux passing through them at a given
instant or do they have a different amount of flux (with the flux
depending on the position of the turn)?

Thanks,
Anand

Hi Everybody,

Firstly, thanks a lot for your detailed replies. Although this
started-off as a thread on my doubts on the transformer, this thread got
(unintentionally) drawn to another topic. One that I was planning to
post here anyway.

The reason I said that getting both - the positive and negative source
from a transformer without a center tap is difficult is that I tried
what a lot of people have recommended here. I built a circuit that had
the two diodes connected to the transformer secondary. One diode had
its anode while the other had its cathode connected to the transformer
secondary. The other end of these diodes were connected to a capacitor
each. These capacitors had a common point which we could call the ground.

I was surprised to find that this ground actually drifted! When I
measured the voltage across the ends of the capacitors (the end
connected to the diodes), the voltage measured was constant. However,
when I measured the voltage across the ground and the other end of the
capacitors, I saw that this voltage changed. So the V+ source and V-
source with respect to the ground was not constant!

I don't know the exact reason what causes this drift. But as a remedy,
I put a resistor in parallel to each of the capacitors. (P. E. Schoen
has posted this).

This stopped the ground from drifting but I don't think one could use
this solution in a practical circuit. A resistor in parallel at the
output of a voltage source will not hold up in case of a heavy load (low
load resistance).

That's why it seemed difficult.

There are ofcourse many other circuits that have been suggested here.
Thanks a ton gentlemen.

Thanks,
Anand

Adding a resistor across each the caps is just loading down the circuit
enough so that stray fluctuations disappear.

Back in the Tube Amplifier days a heavy ballast resistor was often
placed across the B+ to ground (eg. 5K @ 25W - 50W) to stabilize the
voltage when there wasn't a loud signal to process - kept the B+ within
the capacitors' and other components tolerances...

John :-#)#

--
(Please post followups or tech enquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

 

[Michael A. Terrell]

John Robertson wrote:

Adding a resistor across each the caps is just loading down the circuit
enough so that stray fluctuations disappear.

Back in the Tube Amplifier days a heavy ballast resistor was often
placed across the B+ to ground (eg. 5K @ 25W - 50W) to stabilize the
voltage when there wasn't a loud signal to process - kept the B+ within
the capacitors' and other components tolerances...

It also discharged the capacitor, to protect the 'Darwin types'.

 

[John Robertson]

Michael A. Terrell wrote:

John Robertson wrote:
Adding a resistor across each the caps is just loading down the circuit
enough so that stray fluctuations disappear.

Back in the Tube Amplifier days a heavy ballast resistor was often
placed across the B+ to ground (eg. 5K @ 25W - 50W) to stabilize the
voltage when there wasn't a loud signal to process - kept the B+ within
the capacitors' and other components tolerances...


It also discharged the capacitor, to protect the 'Darwin types'.

Yeouch....charged caps can be 'fun'.

And from rec.humour.funny quoting - From *Orbit*, the Journal of the
Rutherford High Energy Laboratory,Didcot, England (31 January 1965) p.12


Ten Commandments of Electrical Safety

(1) Beware of the lightning that lurks in an undischarged
capacitor lest it cause thee to be bounced upon thy backside in a
most ungainly manner.


John ;-#)#

--
(Please post followups or tech enquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

 

[Michael A. Terrell]

John Robertson wrote:

Michael A. Terrell wrote:
John Robertson wrote:
Adding a resistor across each the caps is just loading down the circuit
enough so that stray fluctuations disappear.

Back in the Tube Amplifier days a heavy ballast resistor was often
placed across the B+ to ground (eg. 5K @ 25W - 50W) to stabilize the
voltage when there wasn't a loud signal to process - kept the B+ within
the capacitors' and other components tolerances...


It also discharged the capacitor, to protect the 'Darwin types'.

Yeouch....charged caps can be 'fun'.

And from rec.humour.funny quoting - From *Orbit*, the Journal of the
Rutherford High Energy Laboratory,Didcot, England (31 January 1965) p.12

Ten Commandments of Electrical Safety

(1) Beware of the lightning that lurks in an undischarged
capacitor lest it cause thee to be bounced upon thy backside in a
most ungainly manner.

That's why no broadcast engineer worth his pay ever trusted bleeder
resistors. They had a nasty habit of opening up, with no physical signs
of the failure. A shorting stick inside every cabinet with HV.

 

[Jamie]

John Robertson wrote:

Michael A. Terrell wrote:

John Robertson wrote:

Adding a resistor across each the caps is just loading down the circuit
enough so that stray fluctuations disappear.

Back in the Tube Amplifier days a heavy ballast resistor was often
placed across the B+ to ground (eg. 5K @ 25W - 50W) to stabilize the
voltage when there wasn't a loud signal to process - kept the B+ within
the capacitors' and other components tolerances...



It also discharged the capacitor, to protect the 'Darwin types'.


Yeouch....charged caps can be 'fun'.

And from rec.humour.funny quoting - From *Orbit*, the Journal of the
Rutherford High Energy Laboratory,Didcot, England (31 January 1965) p.12


Ten Commandments of Electrical Safety

(1) Beware of the lightning that lurks in an undischarged
capacitor lest it cause thee to be bounced upon thy backside in a
most ungainly manner.


John ;-#)#

Is that how "Fly Backs" got their name ?

Jamie

 

[John Fields]

On Sat, 01 Sep 2012 12:33:34 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

John Robertson wrote:
Michael A. Terrell wrote:

John Robertson wrote:

Adding a resistor across each the caps is just loading down the circuit
enough so that stray fluctuations disappear.

Back in the Tube Amplifier days a heavy ballast resistor was often
placed across the B+ to ground (eg. 5K @ 25W - 50W) to stabilize the
voltage when there wasn't a loud signal to process - kept the B+ within
the capacitors' and other components tolerances...



It also discharged the capacitor, to protect the 'Darwin types'.


Yeouch....charged caps can be 'fun'.

And from rec.humour.funny quoting - From *Orbit*, the Journal of the
Rutherford High Energy Laboratory,Didcot, England (31 January 1965) p.12


Ten Commandments of Electrical Safety

(1) Beware of the lightning that lurks in an undischarged
capacitor lest it cause thee to be bounced upon thy backside in a
most ungainly manner.


John ;-#)#

Is that how "Fly Backs" got their name ?

Jamie

---
No.

The voltage appearing across a charged capacitor, once the charging
source is removed, is static and is:

Q
V = ---,
C

While the "flyback" voltage appearing across a charged inductor, once
the charging source is removed, is dynamic and is:

L dI
E = ------
dt

--
JF

 

[Jamie]

John Fields wrote:

On Sat, 01 Sep 2012 12:33:34 -0400, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:


John Robertson wrote:

Michael A. Terrell wrote:


John Robertson wrote:


Adding a resistor across each the caps is just loading down the circuit
enough so that stray fluctuations disappear.

Back in the Tube Amplifier days a heavy ballast resistor was often
placed across the B+ to ground (eg. 5K @ 25W - 50W) to stabilize the
voltage when there wasn't a loud signal to process - kept the B+ within
the capacitors' and other components tolerances...



It also discharged the capacitor, to protect the 'Darwin types'.


Yeouch....charged caps can be 'fun'.

And from rec.humour.funny quoting - From *Orbit*, the Journal of the
Rutherford High Energy Laboratory,Didcot, England (31 January 1965) p.12


Ten Commandments of Electrical Safety

(1) Beware of the lightning that lurks in an undischarged
capacitor lest it cause thee to be bounced upon thy backside in a
most ungainly manner.


John ;-#)#


Is that how "Fly Backs" got their name ?

Jamie


---
No.

The voltage appearing across a charged capacitor, once the charging
source is removed, is static and is:

Q
V = ---,
C

While the "flyback" voltage appearing across a charged inductor, once
the charging source is removed, is dynamic and is:

L dI
E = ------
dt

unbelievable.

Jamie

 

[John Fields]

On Mon, 03 Sep 2012 18:28:46 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

John Fields wrote:
On Sat, 01 Sep 2012 12:33:34 -0400, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:


John Robertson wrote:

Michael A. Terrell wrote:


John Robertson wrote:


Adding a resistor across each the caps is just loading down the circuit
enough so that stray fluctuations disappear.

Back in the Tube Amplifier days a heavy ballast resistor was often
placed across the B+ to ground (eg. 5K @ 25W - 50W) to stabilize the
voltage when there wasn't a loud signal to process - kept the B+ within
the capacitors' and other components tolerances...



It also discharged the capacitor, to protect the 'Darwin types'.


Yeouch....charged caps can be 'fun'.

And from rec.humour.funny quoting - From *Orbit*, the Journal of the
Rutherford High Energy Laboratory,Didcot, England (31 January 1965) p.12


Ten Commandments of Electrical Safety

(1) Beware of the lightning that lurks in an undischarged
capacitor lest it cause thee to be bounced upon thy backside in a
most ungainly manner.


John ;-#)#


Is that how "Fly Backs" got their name ?

Jamie


---
No.

The voltage appearing across a charged capacitor, once the charging
source is removed, is static and is:

Q
V = ---,
C

While the "flyback" voltage appearing across a charged inductor, once
the charging source is removed, is dynamic and is:

L dI
E = ------
dt

unbelievable.

---
Tua culpa, non mea.

--
JF

 

[Jamie]

John Fields wrote:

On Mon, 03 Sep 2012 18:28:46 -0400, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:


John Fields wrote:

On Sat, 01 Sep 2012 12:33:34 -0400, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:



John Robertson wrote:


Michael A. Terrell wrote:



John Robertson wrote:



Adding a resistor across each the caps is just loading down the circuit
enough so that stray fluctuations disappear.

Back in the Tube Amplifier days a heavy ballast resistor was often
placed across the B+ to ground (eg. 5K @ 25W - 50W) to stabilize the
voltage when there wasn't a loud signal to process - kept the B+ within
the capacitors' and other components tolerances...



It also discharged the capacitor, to protect the 'Darwin types'.


Yeouch....charged caps can be 'fun'.

And from rec.humour.funny quoting - From *Orbit*, the Journal of the
Rutherford High Energy Laboratory,Didcot, England (31 January 1965) p.12


Ten Commandments of Electrical Safety

(1) Beware of the lightning that lurks in an undischarged
capacitor lest it cause thee to be bounced upon thy backside in a
most ungainly manner.


John ;-#)#


Is that how "Fly Backs" got their name ?

Jamie


---
No.

The voltage appearing across a charged capacitor, once the charging
source is removed, is static and is:

Q
V = ---,
C

While the "flyback" voltage appearing across a charged inductor, once
the charging source is removed, is dynamic and is:

L dI
E = ------
dt


unbelievable.


---
Tua culpa, non mea.

I think you got that backwards, bud!

Jamie

 

[John Fields]

On Tue, 04 Sep 2012 08:04:43 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

John Fields wrote:
On Mon, 03 Sep 2012 18:28:46 -0400, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:


John Fields wrote:

On Sat, 01 Sep 2012 12:33:34 -0400, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:



John Robertson wrote:


Michael A. Terrell wrote:



John Robertson wrote:



Adding a resistor across each the caps is just loading down the circuit
enough so that stray fluctuations disappear.

Back in the Tube Amplifier days a heavy ballast resistor was often
placed across the B+ to ground (eg. 5K @ 25W - 50W) to stabilize the
voltage when there wasn't a loud signal to process - kept the B+ within
the capacitors' and other components tolerances...



It also discharged the capacitor, to protect the 'Darwin types'.


Yeouch....charged caps can be 'fun'.

And from rec.humour.funny quoting - From *Orbit*, the Journal of the
Rutherford High Energy Laboratory,Didcot, England (31 January 1965) p.12


Ten Commandments of Electrical Safety

(1) Beware of the lightning that lurks in an undischarged
capacitor lest it cause thee to be bounced upon thy backside in a
most ungainly manner.


John ;-#)#


Is that how "Fly Backs" got their name ?

Jamie


---
No.

The voltage appearing across a charged capacitor, once the charging
source is removed, is static and is:

Q
V = ---,
C

While the "flyback" voltage appearing across a charged inductor, once
the charging source is removed, is dynamic and is:

L dI
E = ------
dt


unbelievable.


---
Tua culpa, non mea.

I think you got that backwards, bud!

Jamie

---
Shouldn't that be "Lamie"???

--
JF

 

[Fred Abse]

On Mon, 03 Sep 2012 16:08:21 -0500, John Fields wrote:

While the "flyback" voltage appearing across a charged inductor, once the
charging source is removed, is dynamic and is:

L dI
E = ------
dt

Please:

E = -L di/dt

Opposing the change that produces it.

This is .basics, so we need a little pedantry.

--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)

 

[Michael A. Terrell]

John Fields wrote:

Shouldn't that be "Lamie"???

'Lame-nard'.


Maynard A Philbrook JR KA1LPA
Willimantic, CT 06226
We are the original "Brand Rex" company

 

[John Fields]

On Tue, 04 Sep 2012 10:12:08 -0700, Fred Abse
<excretatauris@invalid.invalid> wrote:

On Mon, 03 Sep 2012 16:08:21 -0500, John Fields wrote:

While the "flyback" voltage appearing across a charged inductor, once the
charging source is removed, is dynamic and is:

L dI
E = ------
dt

Please:

E = -L di/dt

Opposing the change that produces it.

This is .basics, so we need a little pedantry.

---
Right you are!

--
JF

 

[John Larkin]

On Tue, 04 Sep 2012 10:12:08 -0700, Fred Abse
<excretatauris@invalid.invalid> wrote:

On Mon, 03 Sep 2012 16:08:21 -0500, John Fields wrote:

While the "flyback" voltage appearing across a charged inductor, once the
charging source is removed, is dynamic and is:

L dI
E = ------
dt

Please:

E = -L di/dt

Opposing the change that produces it.

This is .basics, so we need a little pedantry.

Ground one end of an inductor. Apply a ramp of increasingly-positive
current into the free end. Measure the voltage at that inductor
terminal. It will be positive. So, with that sign convention,

L dI
E = ------
dt

That's the way most people do it.

http://en.wikipedia.org/wiki/Inductor#In_electric_circuits



--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
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