Reservoir inductance....

[none]

In article <i20lobFiroU1@mid.individual.net>,
Sylvia Else <sylvia@email.invalid> wrote:

On 23-Nov-20 1:12 am, albert wrote:
In a dc-dc transformer we mostly see a reservoir capacitor,
that is charged by some control circuit and decharged by the
application.

What about a reservoir inductance? I know there are problems
with saturation, but OTOH it is easier to pump extra energy
into the inductance because the delta E is the product of the
extra current and the current already present.

Is this being used anywhere? Maybe there is a reason why not?

Groetjes Albert


It cannot be the energy store feeding the application circuit, because
any attempt by the application to reduce its current draw abruptly would
result in the input voltage going up.

I see where you getting at. Of course your are right but it doesnot
exclude the circuit I have in mind.
Primary winding connected to a powersupply via switch.
Secondary a circuit that only draws dc current, such as an LED or an LED
protected by a serial diode that can withstand largish voltage.
Say this drives an LED and the current through the LED is measured
by a uP. If the current goes below a certain limit, the uP closes the
switch for a certain time.
The LED gets a reverse voltage, but no current.
Then the switch is opened again and the current is maintained through
the LED.
I should have mentionned it, but the goal is to have a circuit without
capacitor, and the resulting current is allowed to be intermittent as
long as the duty cycle is large. In the intermittent time there may be
a reverse voltage may be as you indicated.
The background is the given that power leds have a small margin between
nominal current and maximum current.
With ideal components the only loss is in the serial diode, and it
may be dispenced with if the total circuit is low voltage and the LED
can withstand the reverse voltage.

Sylvia.

Groetjes Albert
--
This is the first day of the end of your life.
It may not kill you, but it does make your weaker.
If you can\'t beat them, too bad.
albert@spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst

 

[server]

On Mon, 23 Nov 2020 13:40:13 +1100, Sylvia Else <sylvia@email.invalid>
wrote:

On 23-Nov-20 1:12 am, albert wrote:
In a dc-dc transformer we mostly see a reservoir capacitor,
that is charged by some control circuit and decharged by the
application.

What about a reservoir inductance? I know there are problems
with saturation, but OTOH it is easier to pump extra energy
into the inductance because the delta E is the product of the
extra current and the current already present.

Is this being used anywhere? Maybe there is a reason why not?

Groetjes Albert


It cannot be the energy store feeding the application circuit, because
any attempt by the application to reduce its current draw abruptly would
result in the input voltage going up.

Sylvia.

Sorry to be the bearer of bad news, but capacitors are even worse.
When you load them, the voltage goes *down*




--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

 

[whit3rd]

On Wednesday, November 25, 2020 at 6:15:10 AM UTC-8, none albert wrote:

Primary winding connected to a powersupply via switch.
Secondary a circuit that only draws dc current, such as an LED or an LED
protected by a serial diode that can withstand largish voltage.
Say this drives an LED and the current through the LED is measured
by a uP. If the current goes below a certain limit, the uP closes the
switch for a certain time.
The LED gets a reverse voltage, but no current.
Then the switch is opened again and the current is maintained through
the LED.
I should have mentionned it, but the goal is to have a circuit without
capacitor...

This is just the flyback (as in an auto spark coil) but with the input at high
voltage (into a high-inductance tap) with output at low voltage (to the LED).
Yes, it means no capacitor, but... if the intent is to run an LED from
line voltage, the tapped inductor needs a lot of turns (twenty-to-one ratio)
and iron, and capacitors are inexpensive. So are milliwatts, and resistors.