Step Up Booster Circuit | Electronic Project Circuits

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booster 10,000x by One Transistor

For a collector follower with emitter resistor, you’ll often find that the gain per stage is no more than 10 to 50 times. The gain increases when the emitter resistor is omitted. Unfortunately, the distortion also increases. With a ubiquitous transistor such as the BC547B, the gain of the transistor is roughly equal to 40 times the collector current (Ic), provided the collector current is less than a few milliamps. This value is in theory equal to the expression q/KT, where q is the charge of the electron, K is Boltzmann’s constant and T is the temperature in Kelvin.

For simplicity, and assuming room temperature, we round this value to 40. For a single stage amplifier circuit with grounded emitter it holds that the gain Uout /Uin (for AC voltage) is in theory equal to SRc. As we observed before, the slope S is about 40Ic. From this follows that the gain is approximately equal to 40I cRc. What does this mean? In the first instance this leads to a very practical rule of thumb: that gain of a grounded emitter circuit amounts to 40·I c·Rc, which is equal to 40 times the voltage across the collector resistor.
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Read more : http://www.extremecircuits.net/2010/05/10000x-with-one-transistor.html

Be the first to comment - What do you think? Posted by admin - March 5, 2011 at 3:00 am

Categories: Basic electronics, Power Amplifier Tags: current booster, simple transistor amplifier circuit, step up booster circuit

Step-Up Booster Powers Eight White LEDs

Tiny white LEDs are capable of delivering ample white light without the fragility problems and costs associated with ?uorescent backlights. They do pose a problem however in that their forward voltage can be as high as 4 V, precluding them being from powered directly from a single Li-Ion cell. Applications requiring more white LEDs or higher efficiency can use an LT1615 boost converter to drive a series connected array of LEDs. The high efficiency circuit (about 80%) shown here can provide a constant-current drive for up to eight LEDs. Driving eight white LEDs in series requires at least 29 V at the output and this is possible thanks to the internal 36-V, 350-mA switch in the LT1615.

The constant-current design of the circuit guarantees a steady current through all LEDs, regardless of the forward voltage differences between them. Although this circuit was designed to operate from a single Li-Ion battery (2.5V to 4.5V), the LT1615 is also capable of operating from inputs as low as 1 V with relevant output power reductions. The Motorola MBR0520 surface mount Schottky diode (0.5 A 20 V) is a good choice for D1 if the output voltage does not exceed 20 V. In this application however, it is better to use a diode that can withstand higher voltages like the MBR0540 (0.5 A, 40 V). Schottky diodes, with their low forward voltage drop and fast switching speed, are the best match.
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When the FB pin voltage is at less than approximately 600 mV, the switch off-time is increased to 1.5 ms and the current limit is reduced to around 250 mA (i.e., 70% of its normal value). This reduces the average inductor current and helps minimize the power dissipation in the LT1615 power switch and in the external inductor L1 and diode D1. The output current is determined by Vref/R1, in this case, 1.23V/68 = 18 mA). Further information on the LT1615 may be found in the device datasheets which may be downloaded from www.linear-tech.com/pdf/16151fa.pdf
Author: D. Prabakaran
Copyright: Elektor Electronics

Be the first to comment - What do you think? Posted by admin - October 18, 2010 at 12:42 am

Categories: LED Flasher, Lighting Tags: power white led light, step up booster circuit, white led circuit

3V to 12V Step-Up DC Converter by IC LT1073-12

My cousin want buy IC dc converter,I like IC from www.linear.com because good ic,low cost and easy to used.
He are want 3V to 12V DC converter or switching power supply(switching-regulator).
Here is a DC converter Input 3V to output 12V,for electronics circuit.
The important part of the circuit is IC LT1073-12 again.
12V OUTPUT
35mA AT
VBATTERY = 2V
Detail more, Please read in this image circuit.

Read More Source: http://www.linear.com/
Thank you.