Current regulator

N

nescafe

Guest
Hi.
I need to create some kind of charger.
The "charger" will be powered from dc source ( 1,5 AA battery ).

The voltage should stay the same but the current should be regulated
like this:
- charge time: 1 day --> 1,5 / 50mA
- charge time: 2 hours --> 1,5 / 100mA
- charge time: 4 hours --> 1,5 / 200mA
- charge time: 4 hours --> 1,5 / 500mA
- charge time: 7 hours --> 1,5 / 1A
--------------------------------------------
For now i will switch the charge with some micro switch but in future
this should be done with ne555 timer.
Is there any schematics how to make this pcb ?

One input, with multiple regulated current outputs, controlled per micro
switch.

Thnx in advance
 
On 15.09.12 17:10, Jamie wrote:
nescafe wrote:

Hi.
I need to create some kind of charger.
The "charger" will be powered from dc source ( 1,5 AA battery ).

The voltage should stay the same but the current should be regulated
like this:
- charge time: 1 day --> 1,5 / 50mA
- charge time: 2 hours --> 1,5 / 100mA
- charge time: 4 hours --> 1,5 / 200mA
- charge time: 4 hours --> 1,5 / 500mA
- charge time: 7 hours --> 1,5 / 1A
--------------------------------------------
For now i will switch the charge with some micro switch but in future
this should be done with ne555 timer.
Is there any schematics how to make this pcb ?

One input, with multiple regulated current outputs, controlled per
micro switch.

Thnx in advance



You would need to use the CMOS version of the 555 timer to operate at
that low of voltage.

Using a buck boost switch you can generate higher voltages at lower
currents, great for charging I guess.

Unless I miss understood your posting, I assume you're using a single
cell as your DC source ? Or do you mean you want to charge a single cell
from some other DC source?

Jamie
---------------------------
Yes , i did not describe it well...
I want to charge one homemade cell with AA battery.
Click to expand...
 
On Sat, 15 Sep 2012 16:46:03 +0200, nescafe <nescafe@hsd.com> wrote:

The "charger" will be powered from dc source ( 1,5 AA battery ).

The voltage should stay the same but the current should be regulated
like this:
- charge time: 1 day --> 1,5 / 50mA
- charge time: 2 hours --> 1,5 / 100mA
- charge time: 4 hours --> 1,5 / 200mA
- charge time: 4 hours --> 1,5 / 500mA
- charge time: 7 hours --> 1,5 / 1A
Click to expand...
Assuming the load is a battery, that is, something whose internal
chemistry you have no control over, you can control the voltage, or
the current, but not both.
(I think the guy's name was Georg Ohm)
--
Roberto Waltman

[ Please reply to the group,
return address is invalid ]
 
nescafe wrote:

Hi.
I need to create some kind of charger.
The "charger" will be powered from dc source ( 1,5 AA battery ).

The voltage should stay the same but the current should be regulated
like this:
- charge time: 1 day --> 1,5 / 50mA
- charge time: 2 hours --> 1,5 / 100mA
- charge time: 4 hours --> 1,5 / 200mA
- charge time: 4 hours --> 1,5 / 500mA
- charge time: 7 hours --> 1,5 / 1A
--------------------------------------------
For now i will switch the charge with some micro switch but in future
this should be done with ne555 timer.
Is there any schematics how to make this pcb ?

One input, with multiple regulated current outputs, controlled per micro
switch.

Thnx in advance



You would need to use the CMOS version of the 555 timer to operate at
Click to expand...
that low of voltage.

Using a buck boost switch you can generate higher voltages at lower
currents, great for charging I guess.

Unless I miss understood your posting, I assume you're using a single
cell as your DC source ? Or do you mean you want to charge a single cell
from some other DC source?

Jamie
 
nescafe wrote:

On 15.09.12 17:10, Jamie wrote:

nescafe wrote:

Hi.
I need to create some kind of charger.
The "charger" will be powered from dc source ( 1,5 AA battery ).

The voltage should stay the same but the current should be regulated
like this:
- charge time: 1 day --> 1,5 / 50mA
- charge time: 2 hours --> 1,5 / 100mA
- charge time: 4 hours --> 1,5 / 200mA
- charge time: 4 hours --> 1,5 / 500mA
- charge time: 7 hours --> 1,5 / 1A
--------------------------------------------
For now i will switch the charge with some micro switch but in future
this should be done with ne555 timer.
Is there any schematics how to make this pcb ?

One input, with multiple regulated current outputs, controlled per
micro switch.

Thnx in advance



You would need to use the CMOS version of the 555 timer to operate at
that low of voltage.

Using a buck boost switch you can generate higher voltages at lower
currents, great for charging I guess.

Unless I miss understood your posting, I assume you're using a single
cell as your DC source ? Or do you mean you want to charge a single cell
from some other DC source?

Jamie

---------------------------

Yes , i did not describe it well...
I want to charge one homemade cell with AA battery.



How many of these AA cells were you planing on using? Depending on the
Click to expand...
chemistry, lets say a basic carbon type is ~ 900 mAH, that is, you can
expect 900 m-amps to be supplied up to an hour. AFter that, it's all
down hill until dead! ALso, the batter voltage is going to drop so you
most likely will lose it before that as your loaded device will fail,
due to lack of proper operating voltage. SO you can scale that back
according to the voltage drop, too.

So looking at your figures above, I can't see how you plan on getting
7 hours at 1 amp for example?

Jamie
 
On Sat, 15 Sep 2012 16:46:03 +0200, nescafe <nescafe@hsd.com> wrote:

Hi.
I need to create some kind of charger.
The "charger" will be powered from dc source ( 1,5 AA battery ).

The voltage should stay the same but the current should be regulated
like this:
- charge time: 1 day --> 1,5 / 50mA
- charge time: 2 hours --> 1,5 / 100mA
- charge time: 4 hours --> 1,5 / 200mA
- charge time: 4 hours --> 1,5 / 500mA
- charge time: 7 hours --> 1,5 / 1A
--------------------------------------------
For now i will switch the charge with some micro switch but in future
this should be done with ne555 timer.
Is there any schematics how to make this pcb ?

One input, with multiple regulated current outputs, controlled per micro
switch.
Click to expand...
---
With just a single 1.5V AA cell as your source, you're unlikely to
meet all of your goals.

What's your application?

--
JF
 
"nescafe"
I need to create some kind of charger.
The "charger" will be powered from dc source ( 1,5 AA battery ).
Click to expand...

** Better use two ( in series) - cos using just one is never gonna work.

The voltage of a 1.5V cell drops steadily during discharge.



.... Phil
 
One homemade cell can be charged up to 1A (max) and standard voltage is
around 0.75
But to get to this 1A i have to charge the cell on the way i described
before.
----------------------------------
Maybe there is one other solution to make this.
I can connect 15 cells in series and charge it with 12/7Ah battery or
car battery.
I think that this is far better option.
-----------------------------------
OK. How to make this charge process with some 12/7ah or stronger battery ?
Any link to some schematics ?
 
On 2012-09-15, nescafe <nescafe@hsd.com> wrote:
Hi.
I need to create some kind of charger.
The "charger" will be powered from dc source ( 1,5 AA battery ).

The voltage should stay the same but the current should be regulated
like this:
- charge time: 1 day --> 1,5 / 50mA
- charge time: 2 hours --> 1,5 / 100mA
- charge time: 4 hours --> 1,5 / 200mA
- charge time: 4 hours --> 1,5 / 500mA
- charge time: 7 hours --> 1,5 / 1A
--------------------------------------------
For now i will switch the charge with some micro switch but in future
this should be done with ne555 timer.
Is there any schematics how to make this pcb ?

One input, with multiple regulated current outputs, controlled per micro
switch.
Click to expand...
555 is too fast. try CD4060
you won't get 7 hours at 1A from an AA

--
⚂⚃ 100% natural

--- Posted via news://freenews.netfront.net/ - Complaints to news@netfront.net ---
 
On Sun, 16 Sep 2012 11:54:54 +0200, nescafe <nescafe@hsd.com> wrote:

One homemade cell can be charged up to 1A (max) and standard voltage is
around 0.75
But to get to this 1A i have to charge the cell on the way i described
before.
----------------------------------
Maybe there is one other solution to make this.
I can connect 15 cells in series and charge it with 12/7Ah battery or
car battery.
I think that this is far better option.
-----------------------------------
OK. How to make this charge process with some 12/7ah or stronger battery ?
Any link to some schematics ?
Click to expand...
---
You could use a buck regulator.

http://www.onsemi.com/pub_link/Collateral/NCP3065.PDF


View using a fixed-pitch font:

.. +-------------+
.. | +---------+ |
..+12--+-[Rs]-+-|IpK SWC|-+ S1 A
.. | | SWE|-------+-[L]-+->>-[+AA]-<<-+-O-->O-[R1]-+
.. +--------|Vin | | | | C B |
.. | | CT|-+-[R]-+ | | O-[R2]-+
.. |+ | | | | | | C |
.. [Cin] | | | | | | O-[R3]-+
.. | +-|GND COMP|-|-----|-----|------------ + D |
.. | | +---------+ | | | O-[R4]-+
.. | | NCP1365 [Ct] |K [Cout] E |
.. | | | [D] | O-[R5]-+
.. | | | | | |
..GND>-+------+-------------+-----+-----+--------------------------+

S1 is a single pole 5 throw break-before-make switch used to switch
between the various charging currents you want, and if 5% tolerances
in charging currents are acceptable, then the values of the resistors
will be:

LABEL CURRENT RESISTANCE
Ma OHMS
-----------------------------
R1 50 4.7
R2 100 2.4
R3 200 1.2
R4 500 0.47
R5 1000 0.24

--
JF
 
nescafe wrote:
One homemade cell can be charged up to 1A (max) and standard voltage is
around 0.75
But to get to this 1A i have to charge the cell on the way i described
before.
----------------------------------
Maybe there is one other solution to make this.
I can connect 15 cells in series and charge it with 12/7Ah battery or
car battery.
I think that this is far better option.
-----------------------------------
OK. How to make this charge process with some 12/7ah or stronger battery ?
Any link to some schematics ?
Click to expand...
+---------------+-----++
| 2N3904 | |
12 Volt in | ___ |/ |
+-+-------+-+|___|--+--+| |
+ | |> +
- 4.7K | + |/ 2N3055
--- | +--+-|
| | |> 0.25 Ohm
+--------++ | ___ Cell Load
GND | | +---+--+-|___|-+-------+
+ | | | |
V | | .-. |
- + U1 | | |<--+--+
| | 470k /|| | | 10k POT
1N914 Types V \| ___ /+|+ '-' Current Limit
- 2N3904|--|___|--< | |
| <| \-|+---------+|
V | \| .-.
- + LM741 | |
| | Or like it | | 220k
| | '-'
=== === |
GND GND ===
GND


U1 Vee (-) = GND
U1 VCC(+)= 12V
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

That is a voltage limited adjustable current 0..1 amp.
The Max output voltage should be around 1 volt.

As for the timer, in your case, why not use one of those wind up
mechanical timers that has a switch on it? You can get them to extend
to a lot of hours. You find them on car battery chargers etc..

I tried to do that all with transistors, but it was getting messy..
Too many parts. So I through in the OP-AMP as the current sense.

Jamie
 
John Fields wrote:

On Sun, 16 Sep 2012 11:54:54 +0200, nescafe <nescafe@hsd.com> wrote:


One homemade cell can be charged up to 1A (max) and standard voltage is
around 0.75
But to get to this 1A i have to charge the cell on the way i described
before.
----------------------------------
Maybe there is one other solution to make this.
I can connect 15 cells in series and charge it with 12/7Ah battery or
car battery.
I think that this is far better option.
-----------------------------------
OK. How to make this charge process with some 12/7ah or stronger battery ?
Any link to some schematics ?


---
You could use a buck regulator.

http://www.onsemi.com/pub_link/Collateral/NCP3065.PDF


View using a fixed-pitch font:

. +-------------+
. | +---------+ |
.+12--+-[Rs]-+-|IpK SWC|-+ S1 A
. | | SWE|-------+-[L]-+->>-[+AA]-<<-+-O-->O-[R1]-+
. +--------|Vin | | | | C B |
. | | CT|-+-[R]-+ | | O-[R2]-+
. |+ | | | | | | C |
. [Cin] | | | | | | O-[R3]-+
. | +-|GND COMP|-|-----|-----|------------ + D |
. | | +---------+ | | | O-[R4]-+
. | | NCP1365 [Ct] |K [Cout] E |
. | | | [D] | O-[R5]-+
. | | | | | |
.GND>-+------+-------------+-----+-----+--------------------------+

S1 is a single pole 5 throw break-before-make switch used to switch
between the various charging currents you want, and if 5% tolerances
in charging currents are acceptable, then the values of the resistors
will be:

LABEL CURRENT RESISTANCE
Ma OHMS
-----------------------------
R1 50 4.7
R2 100 2.4
R3 200 1.2
R4 500 0.47
R5 1000 0.24

Where is the voltage limiting control? That is needed since he is
Click to expand...
only looking for charge around 0.75 volts, unless he made some mistake
or I did?

I don't know exactly what he is doing , but as cell charge
comes up the current usually drops back, in this circuit here, the
voltage is just going to raise and raise.

The one I showed only goes up to ~ 1.0 Volt.

Did I missed something ?

Jamie
 
On Sun, 16 Sep 2012 20:38:40 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

John Fields wrote:

On Sun, 16 Sep 2012 11:54:54 +0200, nescafe <nescafe@hsd.com> wrote:


One homemade cell can be charged up to 1A (max) and standard voltage is
around 0.75
But to get to this 1A i have to charge the cell on the way i described
before.
----------------------------------
Maybe there is one other solution to make this.
I can connect 15 cells in series and charge it with 12/7Ah battery or
car battery.
I think that this is far better option.
-----------------------------------
OK. How to make this charge process with some 12/7ah or stronger battery ?
Any link to some schematics ?


---
You could use a buck regulator.

http://www.onsemi.com/pub_link/Collateral/NCP3065.PDF


View using a fixed-pitch font:

. +-------------+
. | +---------+ |
.+12--+-[Rs]-+-|IpK SWC|-+ S1 A
. | | SWE|-------+-[L]-+->>-[+AA]-<<-+-O-->O-[R1]-+
. +--------|Vin | | | | C B |
. | | CT|-+-[R]-+ | | O-[R2]-+
. |+ | | | | | | C |
. [Cin] | | | | | | O-[R3]-+
. | +-|GND COMP|-|-----|-----|------------ + D |
. | | +---------+ | | | O-[R4]-+
. | | NCP1365 [Ct] |K [Cout] E |
. | | | [D] | O-[R5]-+
. | | | | | |
.GND>-+------+-------------+-----+-----+--------------------------+

S1 is a single pole 5 throw break-before-make switch used to switch
between the various charging currents you want, and if 5% tolerances
in charging currents are acceptable, then the values of the resistors
will be:

LABEL CURRENT RESISTANCE
Ma OHMS
-----------------------------
R1 50 4.7
R2 100 2.4
R3 200 1.2
R4 500 0.47
R5 1000 0.24

Where is the voltage limiting control? That is needed since he is
only looking for charge around 0.75 volts, unless he made some mistake
or I did?
Click to expand...
---
You did, since you assumed that the terminal voltage of the load was
relevant.

The OP stated that his goal was to push a fixed current through a load
for a specific amount of time, which makes the terminal voltage of the
load unimportant except in the context of the compliance of the
source.
---

I don't know exactly what he is doing , but as cell charge
comes up the current usually drops back, in this circuit here, the
voltage is just going to raise and raise.
Click to expand...
---
As it should, but it'll be limited to whatever current causes the drop
across the current sensing resistor to be 0.235V.
---

The one I showed only goes up to ~ 1.0 Volt.

Did I missed something ?
Click to expand...
---
Yes.

BTW, "+AA" on the schematic should read: "DUC" (Device/s Under Charge)
and there should have been a note to the effect that the DUC could be
a series string of as many of his cells of the same capacity as the
compliance of the source could handle.

--
JF
 
On 16.09.12 23:24, John Fields wrote:
You could use a buck regulator.

http://www.onsemi.com/pub_link/Collateral/NCP3065.PDF


View using a fixed-pitch font:

. +-------------+
. | +---------+ |
.+12--+-[Rs]-+-|IpK SWC|-+ S1 A
. | | SWE|-------+-[L]-+->>-[+AA]-<<-+-O-->O-[R1]-+
. +--------|Vin | | | | C B |
. | | CT|-+-[R]-+ | | O-[R2]-+
. |+ | | | | | | C |
. [Cin] | | | | | | O-[R3]-+
. | +-|GND COMP|-|-----|-----|------------ + D |
. | | +---------+ | | | O-[R4]-+
. | | NCP1365 [Ct] |K [Cout] E |
. | | | [D] | O-[R5]-+
. | | | | | |
.GND>-+------+-------------+-----+-----+--------------------------+

S1 is a single pole 5 throw break-before-make switch used to switch
between the various charging currents you want, and if 5% tolerances
in charging currents are acceptable, then the values of the resistors
will be:

LABEL CURRENT RESISTANCE
Ma OHMS
-----------------------------
R1 50 4.7
R2 100 2.4
R3 200 1.2
R4 500 0.47
R5 1000 0.24
----
Click to expand...
Thank you guys !.
This is exactly what i need.

Regards !
 
John Fields wrote:
On Sun, 16 Sep 2012 20:38:40 -0400, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:


John Fields wrote:


On Sun, 16 Sep 2012 11:54:54 +0200, nescafe <nescafe@hsd.com> wrote:



One homemade cell can be charged up to 1A (max) and standard voltage is
around 0.75
But to get to this 1A i have to charge the cell on the way i described
before.
----------------------------------
Maybe there is one other solution to make this.
I can connect 15 cells in series and charge it with 12/7Ah battery or
car battery.
I think that this is far better option.
-----------------------------------
OK. How to make this charge process with some 12/7ah or stronger battery ?
Any link to some schematics ?


---
You could use a buck regulator.

http://www.onsemi.com/pub_link/Collateral/NCP3065.PDF


View using a fixed-pitch font:

. +-------------+
. | +---------+ |
.+12--+-[Rs]-+-|IpK SWC|-+ S1 A
. | | SWE|-------+-[L]-+->>-[+AA]-<<-+-O-->O-[R1]-+
. +--------|Vin | | | | C B |
. | | CT|-+-[R]-+ | | O-[R2]-+
. |+ | | | | | | C |
. [Cin] | | | | | | O-[R3]-+
. | +-|GND COMP|-|-----|-----|------------ + D |
. | | +---------+ | | | O-[R4]-+
. | | NCP1365 [Ct] |K [Cout] E |
. | | | [D] | O-[R5]-+
. | | | | | |
.GND>-+------+-------------+-----+-----+--------------------------+

S1 is a single pole 5 throw break-before-make switch used to switch
between the various charging currents you want, and if 5% tolerances
in charging currents are acceptable, then the values of the resistors
will be:

LABEL CURRENT RESISTANCE
Ma OHMS
-----------------------------
R1 50 4.7
R2 100 2.4
R3 200 1.2
R4 500 0.47
R5 1000 0.24


Where is the voltage limiting control? That is needed since he is
only looking for charge around 0.75 volts, unless he made some mistake
or I did?


---
You did, since you assumed that the terminal voltage of the load was
relevant.

The OP stated that his goal was to push a fixed current through a load
for a specific amount of time, which makes the terminal voltage of the
load unimportant except in the context of the compliance of the
source.
---


I don't know exactly what he is doing , but as cell charge
comes up the current usually drops back, in this circuit here, the
voltage is just going to raise and raise.


---
As it should, but it'll be limited to whatever current causes the drop
across the current sensing resistor to be 0.235V.
---


The one I showed only goes up to ~ 1.0 Volt.

Did I missed something ?


---
Yes.

BTW, "+AA" on the schematic should read: "DUC" (Device/s Under Charge)
and there should have been a note to the effect that the DUC could be
a series string of as many of his cells of the same capacity as the
compliance of the source could handle.

that's fine, I'll stick with limiting the voltage.
Click to expand...

As a cell increases with voltage, the current drops back. if you are
attempting to maintain current, the voltage will just keep raising until
at some point, the cell could get damaged. A little over is fine, which
is needed, but really, using 12 volt source to charge a .75 volt cell?

Oh, so much for that. I hope you don't get into the charging business.


Jamie
 
nescafe wrote:

On 16.09.12 23:24, John Fields wrote:

You could use a buck regulator.

http://www.onsemi.com/pub_link/Collateral/NCP3065.PDF


View using a fixed-pitch font:

. +-------------+
. | +---------+ |
.+12--+-[Rs]-+-|IpK SWC|-+ S1 A
. | | SWE|-------+-[L]-+->>-[+AA]-<<-+-O-->O-[R1]-+
. +--------|Vin | | | | C B |
. | | CT|-+-[R]-+ | | O-[R2]-+
. |+ | | | | | | C |
. [Cin] | | | | | | O-[R3]-+
. | +-|GND COMP|-|-----|-----|------------ + D |
. | | +---------+ | | | O-[R4]-+
. | | NCP1365 [Ct] |K [Cout] E |
. | | | [D] | O-[R5]-+
. | | | | | |
.GND>-+------+-------------+-----+-----+--------------------------+

S1 is a single pole 5 throw break-before-make switch used to switch
between the various charging currents you want, and if 5% tolerances
in charging currents are acceptable, then the values of the resistors
will be:
LABEL CURRENT RESISTANCE
Ma OHMS
-----------------------------
R1 50 4.7
R2 100 2.4
R3 200 1.2
R4 500 0.47
R5 1000 0.24

----
Thank you guys !.
This is exactly what i need.

Regards !
Good luck. Wouldn't of been my choice.
Click to expand...

Jamie
 
On Mon, 17 Sep 2012 17:54:35 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

John Fields wrote:
On Sun, 16 Sep 2012 20:38:40 -0400, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:


John Fields wrote:


On Sun, 16 Sep 2012 11:54:54 +0200, nescafe <nescafe@hsd.com> wrote:



One homemade cell can be charged up to 1A (max) and standard voltage is
around 0.75
But to get to this 1A i have to charge the cell on the way i described
before.
----------------------------------
Maybe there is one other solution to make this.
I can connect 15 cells in series and charge it with 12/7Ah battery or
car battery.
I think that this is far better option.
-----------------------------------
OK. How to make this charge process with some 12/7ah or stronger battery ?
Any link to some schematics ?


---
You could use a buck regulator.

http://www.onsemi.com/pub_link/Collateral/NCP3065.PDF


View using a fixed-pitch font:

. +-------------+
. | +---------+ |
.+12--+-[Rs]-+-|IpK SWC|-+ S1 A
. | | SWE|-------+-[L]-+->>-[+AA]-<<-+-O-->O-[R1]-+
. +--------|Vin | | | | C B |
. | | CT|-+-[R]-+ | | O-[R2]-+
. |+ | | | | | | C |
. [Cin] | | | | | | O-[R3]-+
. | +-|GND COMP|-|-----|-----|------------ + D |
. | | +---------+ | | | O-[R4]-+
. | | NCP1365 [Ct] |K [Cout] E |
. | | | [D] | O-[R5]-+
. | | | | | |
.GND>-+------+-------------+-----+-----+--------------------------+

S1 is a single pole 5 throw break-before-make switch used to switch
between the various charging currents you want, and if 5% tolerances
in charging currents are acceptable, then the values of the resistors
will be:

LABEL CURRENT RESISTANCE
Ma OHMS
-----------------------------
R1 50 4.7
R2 100 2.4
R3 200 1.2
R4 500 0.47
R5 1000 0.24


Where is the voltage limiting control? That is needed since he is
only looking for charge around 0.75 volts, unless he made some mistake
or I did?


---
You did, since you assumed that the terminal voltage of the load was
relevant.

The OP stated that his goal was to push a fixed current through a load
for a specific amount of time, which makes the terminal voltage of the
load unimportant except in the context of the compliance of the
source.
---


I don't know exactly what he is doing , but as cell charge
comes up the current usually drops back, in this circuit here, the
voltage is just going to raise and raise.


---
As it should, but it'll be limited to whatever current causes the drop
across the current sensing resistor to be 0.235V.
---


The one I showed only goes up to ~ 1.0 Volt.

Did I missed something ?


---
Yes.

BTW, "+AA" on the schematic should read: "DUC" (Device/s Under Charge)
and there should have been a note to the effect that the DUC could be
a series string of as many of his cells of the same capacity as the
compliance of the source could handle.

that's fine, I'll stick with limiting the voltage.
Click to expand...
---
You seem to have missed the point that the voltage into the load will
be automatically limited to that voltage required to drive the
required current through the load and the low side current sensing
resistor.
---

As a cell increases with voltage, the current drops back.
Click to expand...
---
That's true if the cell is being charged with a constant voltage
source, but the OP asked for a constant current source.

That dictates that as the voltage across the cell increases, while
it's being charged, the source's output voltage must increase, as
well, in order to maintain the desired current through the cell.
---

if you are attempting to maintain current, the voltage will just
keep raising until at some point, the cell could get damaged.
Click to expand...
---
The chemistry of the cell determines its terminal voltage, and with a
properly chosen constant current through the cell it can't be damaged.
---

A little over is fine, which is needed, but really,
using 12 volt source to charge a .75 volt cell?
Click to expand...
---
Sure. Why not?

Don't you understand the dynamics of the circuit?
---

Oh, so much for that. I hope you don't get into the charging business.
Click to expand...
---
I've been in the charging business for a long time, and have had my
invoices paid with no complaints.

---
And you?
--
JF
 
On Mon, 17 Sep 2012 17:55:45 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

nescafe wrote:

On 16.09.12 23:24, John Fields wrote:

You could use a buck regulator.

http://www.onsemi.com/pub_link/Collateral/NCP3065.PDF


View using a fixed-pitch font:

. +-------------+
. | +---------+ |
.+12--+-[Rs]-+-|IpK SWC|-+ S1 A
. | | SWE|-------+-[L]-+->>-[+AA]-<<-+-O-->O-[R1]-+
. +--------|Vin | | | | C B |
. | | CT|-+-[R]-+ | | O-[R2]-+
. |+ | | | | | | C |
. [Cin] | | | | | | O-[R3]-+
. | +-|GND COMP|-|-----|-----|------------ + D |
. | | +---------+ | | | O-[R4]-+
. | | NCP1365 [Ct] |K [Cout] E |
. | | | [D] | O-[R5]-+
. | | | | | |
.GND>-+------+-------------+-----+-----+--------------------------+

S1 is a single pole 5 throw break-before-make switch used to switch
between the various charging currents you want, and if 5% tolerances
in charging currents are acceptable, then the values of the resistors
will be:
LABEL CURRENT RESISTANCE
Ma OHMS
-----------------------------
R1 50 4.7
R2 100 2.4
R3 200 1.2
R4 500 0.47
R5 1000 0.24

----
Thank you guys !.
This is exactly what i need.

Regards !
Good luck. Wouldn't of been my choice.

Jamie
Click to expand...
---
Sour grapes?

--
JF
 
John Fields wrote:

On Mon, 17 Sep 2012 17:55:45 -0400, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:


nescafe wrote:


On 16.09.12 23:24, John Fields wrote:


You could use a buck regulator.

http://www.onsemi.com/pub_link/Collateral/NCP3065.PDF


View using a fixed-pitch font:

. +-------------+
. | +---------+ |
.+12--+-[Rs]-+-|IpK SWC|-+ S1 A
. | | SWE|-------+-[L]-+->>-[+AA]-<<-+-O-->O-[R1]-+
. +--------|Vin | | | | C B |
. | | CT|-+-[R]-+ | | O-[R2]-+
. |+ | | | | | | C |
. [Cin] | | | | | | O-[R3]-+
. | +-|GND COMP|-|-----|-----|------------ + D |
. | | +---------+ | | | O-[R4]-+
. | | NCP1365 [Ct] |K [Cout] E |
. | | | [D] | O-[R5]-+
. | | | | | |
.GND>-+------+-------------+-----+-----+--------------------------+

S1 is a single pole 5 throw break-before-make switch used to switch
between the various charging currents you want, and if 5% tolerances
in charging currents are acceptable, then the values of the resistors
will be:
LABEL CURRENT RESISTANCE
Ma OHMS
-----------------------------
R1 50 4.7
R2 100 2.4
R3 200 1.2
R4 500 0.47
R5 1000 0.24

----
Thank you guys !.
This is exactly what i need.

Regards !

Good luck. Wouldn't of been my choice.

Jamie


---
Sour grapes?

Nope, absolutely not. I wouldn't use your circuit for a charger of such
Click to expand...
nature.. I was only trying to be nice to the originator asking for a
sensible circuit that would fit properly and safely, for their needs.

I think you flatter yourself a little too much, you really should
think of others and instead of passing on what you would like to ignore.

We have charging stations at work and none and I mean none of the
chargers are allowed to exceed 10% of the battery voltage, regardless of
condition. You on the other hand, would think it's ok to boil the
battery off, even after its has reached the peak voltage.

Personally, I don't care what you do with your own cells, you can do
what ever and take a chance of generating undesirable effects if you
wish. It's your choice, but to give others advise with out taking that
into consideration, thinking that maybe they don't care any more than
you do is pure foolishness.

BTW, that circuit you posted can be modified very simply to add
limiting voltage function, but since you're so self centered I'll allow
you the honor or making a mess out of it.

Jamie
 
On Mon, 17 Sep 2012 18:44:44 -0500, John Fields
<jfields@austininstruments.com> wrote:

On Mon, 17 Sep 2012 17:55:45 -0400, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

nescafe wrote:

On 16.09.12 23:24, John Fields wrote:

You could use a buck regulator.

http://www.onsemi.com/pub_link/Collateral/NCP3065.PDF


View using a fixed-pitch font:

. +-------------+
. | +---------+ |
.+12--+-[Rs]-+-|IpK SWC|-+ S1 A
. | | SWE|-------+-[L]-+->>-[+AA]-<<-+-O-->O-[R1]-+
. +--------|Vin | | | | C B |
. | | CT|-+-[R]-+ | | O-[R2]-+
. |+ | | | | | | C |
. [Cin] | | | | | | O-[R3]-+
. | +-|GND COMP|-|-----|-----|------------ + D |
. | | +---------+ | | | O-[R4]-+
. | | NCP1365 [Ct] |K [Cout] E |
. | | | [D] | O-[R5]-+
. | | | | | |
.GND>-+------+-------------+-----+-----+--------------------------+

S1 is a single pole 5 throw break-before-make switch used to switch
between the various charging currents you want, and if 5% tolerances
in charging currents are acceptable, then the values of the resistors
will be:
LABEL CURRENT RESISTANCE
Ma OHMS
-----------------------------
R1 50 4.7
R2 100 2.4
R3 200 1.2
R4 500 0.47
R5 1000 0.24

----
Thank you guys !.
This is exactly what i need.

Regards !
Good luck. Wouldn't of been my choice.

Jamie

---
Sour grapes?
Click to expand...
Jamie is too brainless to understand what you designed. His specialty
is boot-licking.

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
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