Solar plate schematics

What are you trying to do?

If you want to power a DC lamp from a solar panel then you'll need a battery to store then energy or there'd be no point.

clicheDM said:

Hi Im newbie...just joined today.I know of basic lamp installations using DC. But it will nicer to use solar on my design. For luck if there's anyone who can share solar plates schematics/diagram for a 5 to 10 watts lamp? I prefer recycled materials if theres any that I can use..[/SIZE]

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I should have a similar project completed and installed this weekend. The attached schematic will switch the load on at night, and off in the daytime. The 10.8 volt battery pack (they were handy) is simply charged through a diode, no over-charge protection is provided. The batteries are 1100 mAH, the solar panel is 100 mA, figure it should take 10 hours of full sunlight to overcharge the batteries, not too likely.

The Solor Panel is made from 4 X 6v 100mA cells, about $5.00 each at American Science & Surplus. The load can be anything 10 volts or less, in my case its an RGB LED fader.

The parts aren't too critical, should breadboard it first to experiment with. The LDR (CdS photo cell) might need some adjustment, that's what the 2.2 meg resistor and trim pot are for, you'll want it to be able cleanly switch at night/day.

I modified this circuit off the web, it's better than a previous circuit I tried, in that it doesn't slowly turn on the load as darkness approaches.

HarveyH42 said:

The batteries are 1100 mAH, the solar panel is 100 mA, figure it should take 10 hours of full sunlight to overcharge the batteries, not too likely.

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Do you live on the equator?? The rated current from your solar panel is its peak current at the equator at noon.
Rechargable batteries are not perfect, so need 14 hours of charging for a full charge when only 10 hours was calculated.
Your battery will not reach anywhere near a full charge.

audioguru said:

Do you live on the equator?? The rated current from your solar panel is its peak current at the equator at noon.
Rechargable batteries are not perfect, so need 14 hours of charging for a full charge when only 10 hours was calculated.
Your battery will not reach anywhere near a full charge.

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The was the point of not worrying about adding battery protection circuitry. I live in Florida, and we don't get a full day of sun (huricane season, evening thunderstorms). Didn't do an real calculations (not an engineer, expert, master... or whatever title this forum has labeled me with this week...). I've read it many times that 10-20% of the battery's rating, is a suitiable charging current. Batteries are 1100 mAH, solar panel is 100 mA, less than 10%.

Last night was the first time I actually got to observe the circuit in action. The RGB fader came on around 8:20pm, almost dark (close enough). Went to bed at 11:00pm and it was still going strong. I consider it a successful run, considering that the solar panel is only getting morning-noon sun, through a screened window, which needs a good cleaning.

The RGB fader works off a 9v battery, so it doesn't need the full 10.8 volts on the battery pack.

I have some cheap RGB fader garden lights. About 2" x 3" of solar cells charging two AA nicads. Charging up here in Canada in the sun for about 6 hrs a day allows them to be on continuously all night for about 10 hrs and they are pretty bright. The blue LED part needs more than the battery's 2.5V so it must have a voltage multiplier circuit inside.

audioguru said:

I have some cheap RGB fader garden lights. About 2" x 3" of solar cells charging two AA nicads. Charging up here in Canada in the sun for about 6 hrs a day allows them to be on continuously all night for about 10 hrs and they are pretty bright. The blue LED part needs more than the battery's 2.5V so it must have a voltage multiplier circuit inside.

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That sounds better then what I've been working on. Do you have a schematic, or are these store bought?

I don't know how long mine went last night, almost 3 hours and still going strong when I went to bed. Might not be great today, been cloudy and expecting it to rain. Need to hit the hardware store for a few items to mount outside and weatherproofing, but its basically ready.

HarveyH42 said:

are these store bought?

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Made in China for Home Depot. $10.00CAN which is about $9.00US.
The RGB LED is a single clear plastic case with 3 LED chips inside.
One light leaked and filled with rain water but still works after draining and sealing.

In case you're interested, here's a small circuit that will allow you to use the higher voltage white LEDs with a 1.5-3V power supply: http://cappels.org/dproj/ledpage/leddrv.htm

There is the most simple DC to DC boosting circuit I have ever seen.

Those circuits are pretty slick, I must say. Ingenuity or what.

I've been fooling around with the last circuit on that page - the solar powered garden light. I wound up adding a 500 ohm trimpot in series with the L1 center tap for light dimming/current limiting, and added a 51 ohm LED resistor. My inductor core came from an old computer motherboard. First one I wound worked fine.

Jack Luminous said:

In case you're interested, here's a small circuit that will allow you to use the higher voltage white LEDs with a 1.5-3V power supply: http://cappels.org/dproj/ledpage/leddrv.htm

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Great find. I think that is the last name of the guy years ago I made a serial RF TX/RX for two Linux boxes to talk..