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How are transistors used to control high voltage?
Transistors are often used as electronic switches, to control loads which require high voltage and current from a lower voltage and current. The most common example you’ll see of this in a physical computing class is to use an output pin of a microcontroller to turn on a motor or other high current device.
Why do I need a lower voltage drop transistor?
You are looking for the wrong thing. The only reason for reducing the voltage drop of the transistor is if you want to operate your circuit at the lowest possible battery voltage. The LED needs the current to be regulated. It doesn’t matter whether you use a resistor, BJT or MOSFET to regulate the current.
How do I make a transistor turn on at a certain voltage?
So, increasing the base resistor (R2) will make the transistor turn on at higher voltage than 1.5V). If you want the LED to turn on when the voltage is below 1.5V *that is, invert what it is now) then you can do it like this: Now when the transistor turns on, it shorts out the LED so the LED goes dark.
How does a base emitter affect a transistor?
So by driving the CTRL input with a voltage that will create a base current, which will cause a current through LED D3. As D3’s current increases D4’s current will decrease, because the sum of the currents is constant. Remember that the base-emitter junction has a 0.7 V voltage drop.
How does a collector feedback circuit maintain stability?
The result is that the collector-feedback circuit maintains a relatively stable Q-point. The reverse action occurs when the temperature decreases. a collector-feedback bias provides very poor stability with negative feedback from collector to base
Why is negative feedback used in common collector amplifiers?
Negative feedback also has the advantage of making amplifier voltage gain more dependent on resistor values and less dependent on the transistor’s characteristics. Common-collector amplifiers have much negative feedback, due to the placement of the load resistor between emitter and ground.
How does rfeedback work in a bipolar junction transistor?
We know that Rfeedback will drop a voltage proportional to emitter current, which is in turn controlled by the base current, which is in turn controlled by the voltage dropped across the base-emitter junction of the transistor (VB-E).
When to choose a replacement transistor for an electronic circuit?
When choosing a suitable replacement transistor for use within an electronic circuit, there are several stages that must be considered when making the choice. These can be progressed in a logical order to narrow down the choice and enable the best alternative for the replacement transistor to be made.
Can a transistor control a shift register IC?
For example, you might put a transistor on the output pin of a 555 timer IC (which produces a variable timing pulse), or a shift register IC (which allows you to produce multiple control signals in parallel) to control high current loads from those devices. Figures 1-11 are the parts you’ll need for this exercise.
Are there any other devices similar to a transistor?
Alternatively, sometimes small voltage regulators are contained in packages similar to that of a transistor. Other devices may also appear in what may appear to be transistor packages at first sight. Careful examination of the application will enable this to be verified.