Re: need HELP with creating an extremely simple BATTERY CHARGING circuit for an LED flower!
- From: ehsjr <ehsjr@xxxxxxxxxxxxxxxx>
- Date: Fri, 29 Dec 2006 08:27:01 GMT
azntwboy@xxxxxxxxx wrote:
thanks!
oh, i was just too lazy to draw the LEDs correctly but i meant for them
to be in parallel.
so how does the circuit prevent the batteries from overcharging?
they're only 60mAh each.
Yup - I missed that spec. The value of R1 would need
to be changed to 210 ohms, but that creates another
problem: there won't be enough current to light
the LEDs while the battery is charging. So a modified
circuit is needed:
Replace the LM317 with an LM7809, add
2 diodes, 2 caps and change the resistor
values (except R2)and the zener as shown below:
---- D1 2N3906
+12V -+-Vin|7809|Vout--+--->|---+---+---- ---+----+----+
| ---- | k | | e\ /c | | |
| Gnd +----+ | [R2] - | | |
| | | | | | | [R3] [R4] [R5]
| | | [R1] | +-----+ | | |
| | | | D2 | | | | |
[C1] | [C2] +--->|---+ | | | |
| | | |+ k |k |+ |+ |+
| | | [NiCd] [Zd] [LED][LED][LED]
| | | | | | | |
Gnd --+-------+---+----+------------+----------+----+----+
C1 = .33 uF, C2 = .1 uF
D1,D2 = 1N4001
R1 = 330 ohms, R2 = 1.2K, R3,R4,R5 = 240 ohms
Zd = 1N4732A (4.7 volt zener diode)
The banded ends of the diodes are marked
with the letter k
The circuit above will charge the batteries and
power the LEDs simultaneously.
Ed
.
ehsjr wrote:
azntwboy@xxxxxxxxx wrote:
Hello,
Could you help me with a personal project that I am working on?
I need help creating a simple rechargable battery circuit.
I am making an acrylic flower with LEDs that make the head glow white.
This is a birthday present for a friend.
My original plan was to just have a wall adapter to power the LEDs, but
now I think it would be cool if I can use rechargable batteries, so
when the flower is unplugged, it will still light up for a short time.
I see a lot of charger controllers for batteries, but they're too
complex for me to understand and I don't know anything about charging
batteries. I'm just an architecture student, so my knowledge of
electronics is very basic. Im afraid to use them because I don't know
what to connect the pins to or how it works.
I also don't have much space to put the components in, so a simple
circuit would be better.
I was wondering will it work if I use a 6v wall adapter to directly
charge a depleted 7.2v battery? Suppose the batteries are drained to
2v. Will the 6v adapter bring the batteries up to 6v? Or will it not
work at all? Will the charging stop automatically or keep going and
overcharge the batteries?
Here is a diagram drawing of what I want to do.
http://www.thomashuang.net/project.gif
Thank you for any advice you can give me.
Thomas
Oops - forgot to mark the zener diode for
you on the diagram. The end of the diode
that has a band on it gets connected to the
base of the transistor and the 1.2K resistor.
Ed
- References:
- need HELP with creating an extremely simple BATTERY CHARGING circuit for an LED flower!
- From: azntwboy
- Re: need HELP with creating an extremely simple BATTERY CHARGING circuit for an LED flower!
- From: ehsjr
- Re: need HELP with creating an extremely simple BATTERY CHARGING circuit for an LED flower!
- From: azntwboy
- need HELP with creating an extremely simple BATTERY CHARGING circuit for an LED flower!
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