Wednesday, September 12, 2012

portable solar lantern circuit uses 6 volt/5 watt solar panels

This portable solar lantern circuit uses 6 volt/5 watt solar panels are now widely available. With the help of such a photo-voltaic panel we can construct an economical, simple but efficient and truly portable solar lantern unit. Next important component required is a high power (1watt) white LED module.

When solar panel is well exposed to sunlight, about 9 volt dc available from the panel can be used to recharge a 4.8 volt /600 mAh rated Ni-Cd batterypack. Here red LED (D2) functions as a charging process indicator with the help of resistor R1. Resistor R2 regulates the charging current flow to near 150mA.

Solar Lantern Circuit Schematic
Assuming a 4-5 hour sunlit day, the solar panel (150mA current set by the charge controller resistor R2) will pump about 600 – 750 mAh into the battery pack. When power switch S1 is turned on, dc supply from the Ni-Cd battery pack is extended to the white LED (D3). Resistor R3 determines the LED current. Capacitor C1 works as a buffer.

Note: After construction, slightly change the values of R1,R2 and R3 up/down by trial&error method, if necessary.

 Source: extremecircuits

Thursday, March 1, 2012

Solar Powered Battery Charger


We propose to build a solar battery charger that will charge a variety of batteries: NiMH, NiCd, Li-ion, lead acid. Although there are solar battery chargers on the market, most are only for one application: cell phone, NiMH batteries, etc. Our charger will have the user input the battery type, capacity, and voltage. It will display the charge status and incorporate various safety systems, including temperature monitoring and battery polarity checking.
Solar Powered Battery Charger - [Link]
source: electronics-lab

Wednesday, February 29, 2012

Solar charger controller circuit diagram

When connecting a solar panel to a rechargeable battery, it is usually necessary to use a charge controller circuit to prevent the battery from overcharging. Charge control can be performed with a number of different circuit types. Lower power solar systems can use a series analog charge controller. Series regulators control the charging current by interrupting the flow of current from the solar panel to the battery when the battery reaches a preset full voltage. MPPT controllers use an inductor for energy storage and a high frequency switching circuit to transfer the energy to the battery.
This circuit is for a shunt-mode charge controller. In a shunt-mode circuit, the solar panel is permanently connected to the battery via a series diode. When the solar panel charges the battery up to the desired full voltage, the shunt circuit connects a resistive load across the battery to absorb the excess power from the solar panel. The main advantage of shunt-mode solar regulation is the lack of a switching transistor in the power path between the solar panel and battery. Switching transistors are non-perfect devices, they waste a percentage of available solar power as heat. Inefficiency in the shunt-mode controller’s switching transistor does not effect charging efficiency, it only turns on when excess power is purposely being wasted.
 Solar power is routed from the PV panel through the 1N5818 Schottky diode to the battery. When the battery reaches the full setpoint, the output on the lower half of the TLC2272 dual op-amp turns on. This activates the IRFD110 MOSFET transistor and connects the 68 ohm 3W load resistor to the battery. The load across the battery causes the battery voltage to drop, and the comparator circuit turns back off. This oscillation continues while solar power is available. The 300nF capacitor across the op-amp slows the oscillation frequency down to a few hertz. The two 100K resistors in series provide a regulated 4.5V reference point for use as comparator reference points.
The 2N3906 transistor is wired with a zener diode in its base circuit, when the PV voltage is above 12V, the 2N3906 transistor turns on and enables the comparator circuit. The upper half of the TLC2272 op-amp inverts the dump load control signal, this is used to power the high intensity red LED. The LED turns on when the battery reaches the full setpoint. The LED does not waste any useful charging power since it only turns on when the battery is full.
The 78L09 IC provides 9V regulated power to the comparator circuitry. Operational power for this circuit is provided entirely from the PV panel, there is virtually no power taken from the battery at night.
This circuit can be modified for higher amperage by replacing the 1N5818 diode, 68 ohm load resistor and IRFD110 MOSFET with higher power components. If the load resistor is connected directly across the PV panel at noon on a sunny day, the PV output voltage should drop to 12V or less. Higher power PV panels will require a resistor with lower ohms and a higher wattage rating. In cold climates, it may be useful to use the load resistor’s heat to keep the battery warm.
Operation of a high power version of this circuit with a wind generator should be possible, although the author has not tried this. For a 20 amp version of this circuit, the IRFD110 MOSFET should be replaced with an IRFZ44N and the 1N5818 schottky diode should be replaced with a 20L15T. Both of these parts should have large heat sinks. The 68 ohm/3W resistor should be changed to a much larger resistor, An 0.6 ohm/250W resistor would be able to handle 20 amps at 12V.
source :

tags: solar panel, solar and system

Solar charger circuit diagram


A simple solar charger circuit can be constructed using this circuit diagram .
The nominal voltage of the solar charger circuit module is determined by the number of battery cells to be charged. Because of the typical voltage drop of 0.3 to 0.4 V across Schottky diode D1, the nominal voltage should exceed the charge voltage set on P1 by about 0.3–0.4 V .
The solar panel for this project is a typical solar module that consists of eight series connected solar cells. In sunshine the solar panel will supply about 140 mA -200mA or more( depends of the solar panel used ) at 8 times 0.45 V = 3.6 V.
If you don’t find a zenner diode with this value you can use two normal diodes connected in forward bias ( cathode connected to the ground ) .
Using the P1 potentiometer you can set the final charging voltage at the desired voltage .
The voltage across the batteries is continuously monitored by the circuit around T2.
When the voltage rises above a certain level (full charge ), a power resistor is switched in parallel with the solar panel, which causes output voltage of the solar panel to drop and stops the batteries from being charged .
source: electroniccircuitsdesign

tags:  solar panel roads, Solar, solar panel

Explaining solar cells

As renewable energy is becoming integrated into our everyday lives, new terms such as solar panel, photovoltaic and solar cell are more common and new devices, such as outdoor LED lighting are using this technology. The sun emits many forms of radiation. The best way to describe this is that there are ‘waves’ of energy that radiate from the sun at different frequencies.
This is only partially the truth as there is both a wave and particle nature to light.
The light spectrum is divided into different sections. It begins with the highest, gamma rays and ends with the lowest, long wave radio. Only a small portion of this is visible, called the visible spectrum and this occurs towards the middle of the range which lies between Ultraviolet and Infrared frequencies. Ultraviolet radiation is what burns the skin and can cause skin cancer. It is blocked by most types of glass and is partially reduced by the atmosphere especially the ozone layer. Infrared radiation is what provides the earth with heat and it is that which is trapped by green house gasses, carbon dioxide mainly and is causing global warming.
Infrared radiation is targeted by solar panels. This basically uses the energy generated by the radiation to heat water in pipes that flows and generates electricity. This can be used to charge a battery which could then power said LED lighting. As mentioned previously there is a dual nature to light. It consists of both a particle and a wave. It might help to think of the particles moving in a wave like pattern but the reality is more complex than that. The important thing to remember is that the light particle, the photon, is what is targeted by a solar cell.
Generally speaking the solar cell works by providing energy to a semiconducting material, most commonly silicon, so that electrons within the material are released from the bonds to their atoms in the semiconductor.
The arrangement of the cell into strips of conductor and semiconductor allow these freed electrons to move. They move in a directed manner away from the incoming energy, the photons, creating a flow of electrons more commonly known as current.
A high incoming rate of photons is required to release the electrons. This creates problems as much of the higher energy (higher frequency) waves emitted by the sun are blocked; the glass protective covering reflects light requiring anti-reflection membranes, glass blocks ultraviolet and the lower range of frequencies like infrared do not have enough energy to have much of an effect on the panels. Thus these panels only really target the visible spectrum which is only a small proportion of the sun’s energy.
Yet, with the improvements to the semiconductors, the anti reflection layers and the methods of directing the released electrons the efficiency of solar cells has dramatically improved. Huge fields of cells are being created in deserts and mountainous regions that can now produce kilowatts of energy.
Combined with the improvements of energy efficient products, such as LED lighting, this is becoming a valuable resource. In fact, the low energy of LED lighting is one of the most important improvements as it helps to alleviate the greatest weakness of solar cells – night time.
source: electronics-lab
Tags: cells, Led, Photovoltaics, Solar 

Tuesday, February 28, 2012

Download TinyCAD open source schematic


TinyCAD is an open source schematic capture program for MS Windows. Use TinyCAD to produce professional circuit diagrams and export net list information to PCB applications.


TinyCAD is a program for drawing circuit diagrams commonly known as schematic drawings. It supports standard and custom symbol libraries. It supports PCB layout programs with several netlist formats and can also produce SPICE simulation netlists.


  • Flat or Hierarchical Schematic Entry
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Download TinyCAD_2.80.03.514_Production_Setup.exe 

TinyCAD Web Site

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