# Circuits

BC307/308/309 Switching and Amplifier Applications - BC30x.pdf. Online Circuit Simulator with SPICE | PartSim.

## PCBs

Projects. 200 Transistor Circuits. This will clear-up a lot of mysteries of the solar panel. Many solar panels produce 16v - 18v when lightly loaded, while other 12v solar panels will not charge a 12v battery. Some panels say "nominal voltage," some do not give any value other than 6v or 12v, and some specify the wrong voltage. You can't work with vague specifications. You need to know accurate details to charge a battery from a solar panel. There are 3 things you have to know before buying a panel or connecting a panel to a battery. 1. 1. 2. You can clearly see the 11 cells of this panel and it produces 6.6v when lightly loaded.

This panel claims to be 18v, but it clearly only produces 14.4v. 3. ADDING A DIODE Some solar panels will discharge the battery (a small amount) when it is not receiving sunlight and a diode can be added to prevent discharge. PREVENTING OVERCHARGING There are two ways to prevent overcharging the battery. 1. Here is the simplest and cheapest regulator to charge a 12v battery. TALKING ELECTRONICS LED Torch.

A LED torch is one of the simplest projects you can build and it's very interesting as it uses a super-bright white LED. In the history of LED production, red LEDs were the first to be invented and their output was so dim you could barely see if they were illuminated. You needed a darkened room to see them at all. Then came green, yellow and orange LEDs. As time went by, the brightness improved and it came to a point where the output would shine into the surrounding air. These were called Super-bright LEDs. Then came the blue LED. At first it was dull, but gradually the output increased to a dazzling glare.

JOULE THIEF The web is filled with circuits similar to "CIRCUIT A" below. Although they work, the performance and efficiency can be increased an amazing 300% by simply adding a capacitor. HOW THE CIRCUIT WORKS The transformer is configured as a BLOCKING OSCILLATOR and the cycle starts by the transistor turning on via the 2k7 base resistor. BIKE FLASHER - Amazing! MOSFET fall time too slow - Electrical Engineering - Stack Exchange. Concise electronics for geeks. Copyright (C) 2010 by Michal Zalewski <lcamtuf@coredump.cx> There are quite a few primers on electronics on the Internet; sadly, almost all of the top hits resort to gross oversimplifications (e.g., hydraulic analogies), or convenient omission, when covering subtle but incredibly important topics such as the real-world behavior of semiconductors.

There are some exceptions, to be sure - but they tend to suffer from another malady: regressions into mundane, academic rigor, complete with differential equations and complex number algebra in transient analysis - a trait that is highly unlikely to be accessible, or even useful, to hobbyists. The physics of conduction [link] As you probably recall from your school years, the dated but still useful Bohr model of the atom explains that atoms consist of a dense center (nucleus) with a variable number of protons and neutrons.

The strongly bound and heavy nuclei of stable isotopes do not undergo any structural changes under everyday circumstances. JeremyBlum.com. NerdKits. Solar Joule Thief. Photo from Petmar0 on Flickr Pete responded in the comments to the the call for designs in the Rural Celly Charger article on Saturday. How about connecting a joule-thief circuit (DC-DC upconverter) to a cap on one side and a small solar cell (like the ones in calculators) on the other? You pull off of the cap to the cell phone directly. If I remember correctly, most cell phones have internal Vregs between the battery and the rest of the circuitry, so that takes care of your OV protection.

I’ll see if I can build this, and then get back to you. Within a few hours on his busy Saturday, he had a rough build tested and posted up. Photo from petmar0 on Flickr The original article on Women of Uganda Network, or WOUGNET, told of how a Ugandan woman built her own charger after an unscrupulous vendor nicked her good battery and replaced it with a nearly dead one. The comments offered a number of perspectives on the problem and possible solutions.

How can you add to this idea? Chris Connors Related. Joule Thief. The first step is to wind the toroid. I found mine in an old computer power supply, and it works fine for me. Toroids are donut-shaped objects like in the picture, and can be attracted by a magnet. You can find toroids in a few places. Old computer motherboards, XBOX and X360 motherboards have them (don't take them unless it's dead!). You can find toroids in computer power supplies, or you could buy them at your nearest RadioShack. Take your two strands of wire, and twist the ends together. Thread the twisted end through the toroid, then take the other two ends (Not twisted together) and wind it once around the toroid. Keep winding, making sure you wind the coils tight. Ideally, you want about 8-11 turns on your toroid. Once you wind around the whole toroid, cut off the extra wire, making sure you leave a couple of inches for soldering. Strip some insulation off the wires, then take a wire from each side, making sure they are of the OPPOSITE COLOR.

Joule Thief. 555 Square Wave Generator. This is a simple square waveoscillator using a 555 timer chip. A timing interval starts when the trigger input ("tr") goes lower than 1/3 Vin, or 3.33V. When this happens, the 555 output goes high, and the 555 waits for the threshold input ("th") to reach 2/3 Vin, or 6.67V. As the capacitor charges, the threshold input slowly rises until it reaches the required level. Then, the timing interval ends, the output goes low, and the capacitor is discharged through the "dis" input. When the capacitor is discharged enough so that the trigger reaches 3.33V, then a new timing interval begins.

The end result is a square wave. Next: 555 Internals Previous: Dynamic RAMIndex java@falstad.comGenerated Wed Apr 9 2014. 555 timer. 555 Timer Navigation Custom Search Learn about the 555 by building the DOCTRONICS Safety Lights Project: 1. Pin connections The 555 timer is an extremely versatile integrated circuit which can be used to build lots of different circuits. You can use the 555 effectively without understanding the function of each pin in detail.

Frequently, the 555 is used in astable mode to generate a continuous series of pulses, but you can also use the 555 to make a one-shot or monostable circuit. 2. Astable circuits produce pulses. The button allows you to open a simulation of this circuit in Yenka©, the electronics simulation program from Crocodile Clips Limited. At the moment, Yenka is available for free download to home users from As you can see, the frequency, or repetition rate, of the output pulses is determined by the values of two resistors, R1 and R2 and by the timing capacitor, C. The design formula for the frequency of the pulses is: The period, t, of the pulses is given by: Current Mirror (with MOSFETs) - Circuit Simulator. Using a FET as a Voltage Controlled Resistor. An fet can be used as a voltage controlled resistor (vcr) where the resistance between the drain and source is controlled by the gate-source voltage.

The resulting resistor is unfortunately non-linear; however, a simple linearisation circuit means that the fet vcr can be used even in situations where the non-linearities would cause difficulties. I have used this technique successfully both at audio and video frequencies. Typical applications include attenuators, amplifier and modulation circuits. Consider the characteristics of a JFET with pinch-off voltage = VP : There are two distinct regions - the saturation region (or pentode region) and the ohmic (or triode) region. In the saturation region the drain current is almost entirely independent of the drain-source voltage whilst in the ohmic region the drain current depends on the drain-source voltage. The equation of the curve that separates the triode and pentode regions is: In the triode region: If VDS and VGS = 0, then: Let: R1 = R2 Thus: Sample-and-Hold - Circuit Simulator. Open source electronic projects. Soft Latching Power Switch Circuit.

Schmitt trigger provides toggle function - 2011-03-17 10. CircuitLab. SchemeIt | Free Online Schematic Drawing Tool.