Do More

Description This device is designed to be a simple, inexpensive ‘comparator’, intended for use in a solar cell power supply setup where a quick ‘too low’ or ‘just right’ voltage indicator is needed. The circuit consists only of one 5V regulator, two transistors, two LEDs, five resistors, two capacitors, and one small battery. Although a 4-V battery is indicated, 4.5 V (3 alkalines in series) or 3.6 V (3 NiCd cells in series) will also work. The specifications of voltage regulator IC1 are mainly determined by the size and number of the solar cells and the current pull of the equipment connected to the output. Here the low-drop 4805 is suggested but other regulators may work equally well as long as you observe the output voltage of the solar cells. Transistors T1 and T2 are complementary types i.e. one each of the pnp and npn variety. Circuit diagram: Although the ubiquitous BC557B (pnp) and BC547B (npn) are indicated, any small-signal equivalents out of the junk box will probably do....

4.2.2 Leclanché cell The most common type of primary cell in use is the Leclanché cell. In its wet form, it consists of a glass jar containing: a saturated solution of sal ammoniac (ammonium chloride) as the electrolyte, a zinc rod as the negative electrode, and a plate of carbon as the positive electrode. 4.2.2.1 Wet Leclanché Cell Wet Leclanché cell A mixture of manganese dioxide and powdered carbon is pressed around the carbon rod and then enclosed in a porous pot which the solution can soak through. The manganese dioxide acts as the depolarizer, while the powdered carbon gives greater conductivity. The e.m.f. of the Leclanché cell is 1.5 V and the internal resistance of a normal size cell is 1 Ohm. The wet cells are now going obsolete.  They were once a majorly used to supply power to land-line telephone installations in remote areas.

Nano-electronics research center imec announced today at Intersolar Europe, a new efficiency record for its large area n-type PERT (passivated emitter, rear totally diffused) crystalline silicon (Cz-Si) solar cell, now reaching 22.5 percent (calibrated at ISE CalLab). It is the highest efficiency achieved for a two-side-contacted solar cell processed on six inch commercially available n-type Cz-Si wafers without the use of passivated contacts. N-type silicon solar cells are considered as promising alternatives to p-type solar cells for next generation highly efficient solar cells thanks to their ability to withstand light-induced degradation and to their higher tolerance to common metal impurities. [ ]