Solar Garden Lamp | Electronic Project Circuits

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Solar Lamp Using PR4403

The PR4403 is an enhanced cousin of the PR4402 40mA LED driver. It has an extra input called LS which can be taken low to turn the LED on. This makes it very easy to build an automatic LED lamp using a rechargeable battery and a solar module. The LS input is connected directly to the solar cell, which allows the module to be used as a light sensor at the same time as it charges the battery via a diode. When darkness falls so does the voltage across the solar module: when it is below a threshold value the PR4403 switches on. During the day the battery is charged and, with the LED of, the driver only draws 100µA.
At night the energy stored in the battery is released into the LED. In contrast to similar designs, here we can make do with a single 1.2 V cell. The PR4403 is available in an SO-8 package with a lead pitch of 1.27 mm. The other components are a 1N4148 diode (or a Schottky 1N5819) and a 4.7µH choke. Pin 2 is the LS enable input, connected directly to the solar module. According to the datasheet, it is possible to connect a series resistor at this point (typ. 1.2 M) to increase the effective threshold voltage. The LED will then turn on slightly earlier in the evening before it is not completely dark. Pins 3 and 6 of the device must be connected together and together form the output of the circuit.
Burkhard Kainka
Elektor Electronics 2008
Read more : http://www.extremecircuits.net/2010/05/solar-lamp-using-pr4403.html

Be the first to comment - What do you think? Posted by admin - February 14, 2011 at 4:05 am

Categories: Lighting Tags: led lamp, solar garden lamp

Solar garden lamp by CDS photocell control

Reverse engineered circuit diagram of yet another commercially produced solar garden lamp. This one depends upon a CDS photocell to turn the light on at night, and although more complex than the circuits, it allows the battery to charge more efficiently.

Solar Power walkway marker Led display

These are the little lights with the stake on the bottom that you can push into the ground along your driveway or sidewalk and have the solar panel on top. The solar cell charges a AA NiCd battery during the day and at night the battery powers the LED. The circuit board in this particular model was originally designed to hold a pair of 5mm amber LEDs, but the manufacturer apparently found a source of higher power 10mm amber LEDs and the final product only needs one of these. Due to the limited space, many of the components are surface mount. The transistors are both 2N3904 equivalent surface mounts. Unfortunately, the capacitor is also surface mount and is unmarked.

The charging circuit is fairly simple and has a photovoltaic solar cell to charge the battery and a diode to prevent the battery from powering the cell when it’s dark. Now moving along, there is a cadmium sulphide (CdS) photo resistor, a 10k resistor and a 1k resistor that forms a voltage divider at the base of Q1. When light hits the photo resistor, it has a low resistance which is amplified by the transistor. The collector is tied to the base of the left hand transistor, so when it’s on it clamps its base to ground and prevents it from oscillating. When it’s dark and the CdS Cell has a high resistance, the right transistor is off which allows the rest of the circuit to begin oscillating.

Read More Source: http://silenceisdefeat.org/~lgtngstk/Sites/tls.html
Thank you.