Forums

Current regulator

Started by nescafe September 15, 2012
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



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
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.
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
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:

> 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 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.
--- 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 ).
** 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.
555 is too fast. try CD4060 you won't get 7 hours at 1A from an AA -- &#9858;&#9859; 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 ?
--- 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