Schematic Diagram: solar

Showing posts with label solar. Show all posts

Saturday, November 8, 2014

Solar Panel Current Meter

This circuit is used to measure the current from a solar panel. It has very low power loss for currents in the 0-10A range. It also works as a general purpose DC current meter. The circuit can be used on either the positive or negative side of a DC circuit.

Solar Panel Current Meter

Specifications

Measured Current: 0-10 Amps DC
Circuit Voltage: Will work with DC circuits at any practical voltage.
Accuracy: approximately 2%, depending on the meter movement.

Theory

The current to be measured flows through the 0.01 ohm resistor which causes a small voltage drop across the resistor. The 100 microamp meter is set up with the series 50 ohm and 500 ohm variable resistor in a voltage measurement configuration to measure this voltage drop. The 500 ohm variable resistor is used to adjust the meters full scale reading. The 50 ohm resistor limits the maximum current to the meter no matter what setting is on the 500 ohm resistor, this protects the meter from passing too much current and burning up. The series resistance of the meter, 500 ohm (or less) variable resistor and 50 ohm resistor should total 1000 ohms. Different meters may require a different variable resistor to achieve the 1000 ohm value.

Construction

Build the meter into a metal box with the meter and two connectors mounted on the outside of the box.

Alignment

Put the meter circuit in series with a known current meter such as a digital VOM meter set to measure current. Run a known current through both meters. Adjust the 500 ohm resistor until both meters read the same current. A good way to get a known current is to put a 12V lead acid battery in series with a 2 ohm 100 watt current limiting resistor. This will produce approximately 6 Amps of current. Put the two meters in series with this loop and adjust for the same reading. Beware, the resistor will get fairly hot in a short time.

Use

Connect this circuit in series with a nominal 12V or 24V solar panel array. The meter can go in either the positive or negative side of the solar panel circuit. The current flowing through the solar panel to the load will be shown on the meter.

Parts

1x 100 microamp DC meter
1x 0.01 ohm 5 W resistor
1x 50 ohm 1/4 W resistor
1x 500 ohm 10 turn variable resistor
2x banana plugs or a 2 pin screw type terminal block.
1x metal box

Sunday, October 5, 2014

Solar IPod Charger Project and Schematic

Solar iPod Charger Schematic

The Solar Panel

To accomplish our iPod solar charger we acclimated a 250mA 6 Volt Solar Console (available in the REUK Shop). Alike in the brightest sunshine the voltage is not badly aloft that of the iPod battery, and the accepted is affluence abundant to allegation the array in a few hours in ablaze altitude (even in the UK!).

A blocking diode should be acclimated (in the absolute solar console lead) to anticipate the iPod array from boring clarification at night if it is still affiliated to the panel. Unforunately this after-effects in up to 0.7 Volts actuality absent as calefaction in the diode, so it can be larboard out if you adopt to accept a faster charger which will allegation the array in lower ablaze conditions.

Note that abounding solar panels are supplied with a branch adapted blocking diode.

In adjustment to adapt the voltage from our 6 Volt solar console we acclimated an LM317T dent (available from the REUK Shop) in the afterward cool simple circuit:

Voltage

Voltage Regulator

...where R1 is a 270 Ohm resistor, and R2 is theresistor used to set the output voltage according to the following equation:

R2 = R1 * ( (VOUT/1.25) -1 )

Since our desired charging voltage is 5 Volts, we see that ideally R2 would be 270 * ((5/1.25) -1) = 810 Ohms. This is not a standard resistor size, however we had an 820 Ohm resistor which should result in an output voltage of 5.05 Volts.

Wiring up the aloft ambit on a prototyping breadboard with a 270 Ohm R1 resistor, and 820 Ohm R2 resistor we can affirm that the achievement voltage is 5.06 Volts - absolute for our iPod charger. It is capital to analysis that the achievement voltage is about 5 Volts application a acceptable multimeter afore attempting to allegation your iPod or the array and/or iPod itself could be damaged.

iPod Solar Charger Prototyping

Connecting the Charger to the iPod

The iPod is supplied with a USB cable. One end is acquainted into the iPod and the added end has a macho USB-A plug.

It can generally be cheaper to buy a cable with a adapted changeable USB-A adapter and cut it off to use in this project. Simply affix the red USB cable wire to the 5V absolute achievement from the LM317T, and the atramentous USB cable wire to the arena (negative).

According the blueprint beneath the 5 Volt achievement from the LM317T should be affiliated to pin 1, and the arena (negative) affiliated to pin 4.

Friday, September 12, 2014

Solar Powered SLA Battery Maintenance

This schema was designed to ‘baby-sit’ SLA (sealed lead-acid or ‘gel’) batteries using freely available solar power. SLA batteries suffer from relatively high internal energy loss which is not normally a problem until you go on holidays and disconnect them from their trickle current charger. In some cases, the absence of trickle charging current may cause SLA batteries to go completely flat within a few weeks. The schema shown here is intended to prevent this from happening. Two 3-volt solar panels, each shunted by a diode to bypass them when no electricity is generated, power a MAX762 step-up voltage converter IC.

Circuit diagram:

Solar Powered SLA Battery Maintenance Circuit Diagram

The ‘762 is the 15-volt-out version of the perhaps more familiar MAX761 (12 V out) and is used here to boost 6 V to 15 V.C1 and C2 are decoupling capacitors that suppress high and low frequency spurious components produced by the switch-mode regulator IC. Using Schottky diode D3, energy is stored in inductor L1 in the form of a magnetic field. When pin 7 of IC1 is open-schemaed by the internal switching signal, the stored energy is diverted to the 15-volt output of the schema. The V+ (sense) input of the MAX762, pin 8, is used to maintain the output voltage at 15 V. C4 and C5 serve to keep the ripple on the output voltage as small as possible. R1, LED D4 and pushbutton S1 allow you to check the presence of the 15-V output voltage.

D5 and D6 reduce the 15-volts to about 13.6 V which is a frequently quoted nominal standby trickle charging voltage for SLA batteries. This corresponds well with the IC’s maximum, internally limited, output current of about 120 mA. The value of inductor L1 is not critical — 22 µH or 47 µH will also work fine. The coil has to be rated at 1 A though in view of the peak current through it. The switching frequency is about 300 kHz. A suggestion for a practical coil is type M from the WEPD series supplied by Würth (www.we-online.com). Remarkably, Würth supply one-off inductors to individual customers. At the time of writing, it was possible, under certain conditions, to obtain samples, or order small quantities, of the MAX762 IC through the Maxim website at www.maxim-ic.com.

Streampowers

Wednesday, September 10, 2014

RGB Solar Lamp Wiring diagram Schematic

This deluxe solar-powered light uses a battery and solar cells salvaged from a solar lamp with a four-cell battery (4.8 V nominal terminal voltage).

Circuit diagram :

RGB Solar Lamp Circuit Diagram

The schema can operate from any DC voltage around this value and its current consumption, at 20 mA, is low. This means that the battery can give up to ﬁve days of operation. The schema consists of an Atmel ATtiny microcontroller which drives a red, a green and a blue LED directly from three port pins. Series resistors are of course included to limit the LED current. The microcontroller drives the LEDs in sequence to produce an RGB running light effect. The microcontroller is also responsible for ensuring that the light automatically switches on when it gets dark and off when it is light. The light sensor is made from one of the solar cells from a bro-ken solar lamp (it is more common for the battery to fail rather than the solar cells).

The power output of this cell is not important, as the microcontroller only measures its output voltage using its internal A/D converter connected to pin PB4. The project is ideal for beginners, as a ready-programmed microcontroller is avail-able from the Elektor Shop (order code 100581-41).

Source by : Streampowers

Thursday, August 7, 2014

Pump Controller For Solar Hot Water System

This schema optimises the operation of a solar hot water system. When the water in the solar collector is hotter than the storage tank, the pump runs. The schema comprises two LM335Z temperature sensors, a comparator and Mosfet. Sensor 1 connects to the solar collector panel while Sensor 2 connects to the hot water panel. Each sensor includes a trimpot to allow adjustment of the output level. In practice, VR1 and VR2 are adjusted so that both Sensor 1 and Sensor 2 have the same output voltage when they are at the same temperature. The Sensor outputs are monitored using comparator IC1.

When Sensor 1 produces a higher voltage than Sensor 2, which means that sensor 1 is at a higher temperature, pin 1 of IC1 goes high and drives the gate of Mosfet Q1. This in turn drives the pump motor. IC1 includes hysteresis so that the output does not oscillate when both sensors are producing a similar voltage. Hysteresis comprises the 1MO feedback resistor between output pin 1 and non-inverting input pin 3 and the input 1kO resistor. This provides a nominal 12mV hysteresis so that voltage at Sensor 1 or Sensor 2 must differ by 12mV for changes in the comparator output to occur.

Circuit diagram:

Pump Controller For Solar Hot Water System

Since the outputs of Sensor 1 and Sensor 2 change by about 10mV/°C, we could say that there is a degree of hysteresis in the comparator. Note that IC1 is a dual comparator with the second unit unused. Its inputs are tied to ground and pin 2 of IC1 respectively. This sets the pin 7 output high. Since the output is an open collector, it will be at a high impedance. Mosfet Q1 is rated at 60A and 60V and is suitable for driving inductive loads due to its avalanche suppression capability. This clamps any inductively induced voltages exceeding the voltage rating of the Mosfet.

The sensors are adjusted initially with both measuring the same temperature. This can be done at room temperature; adjust the trimpots so that the voltage between ground and the positive terminal reads the same for both sensors. If you wish, the sensors can be set to 10mV/°C change with the output referred to the Kelvin scale which is 273K at 0°C. So at 25°C, the sensor output should be set to (273 + 25 = 298) x 10mV or 2.98V.

Note:

The sensors will produce incorrect outputs if their leads are exposed to moisture and they should be protected with some neutral cure silicone sealant. The sensors can be mounted by clamping them directly to the outside surface of the solar collector and on an uninsulated section of the storage tank. The thermostat housing is usually a good position on the storage tank.

Source by : Streampowers