When the capacitor has sufficient charge, it discharges through the emitter junction of the BC557 transistor. This charge, then flows through the base junction of BC547 making it conduct and thereby powering the LED. You will need to understand basic transistor switching theory to truly understand the operation.
Which resistor is used for the base of a BJT transistor?
The breadboard circuit of the above circuit is shown below. So, for this circuit, the first transistor is the BC547 while the second is the BC557. So the first 2.2KΩ resistor that goes into the base of the BC547 is used to limit current that goes to the BC547. You always need resistors for the bases of BJT transistors.
What is the difference between the BC547 and the bc557?
The BC547 is a BJT NPN transistor. The BC547 can handle a maximum voltage of 65V at its collector. The datasheet for the BC547 can be found at the following link: BC547 NPN Transistor Datasheet. The BC557 is a BJT PNP transistor.
What is the function of a BC547 limit resistor?
Current Limiter: Two BC547 transistors when connected as shown in the article, provides a useful feature of controlling the amount of current drawn by the load. The arrangement makes sure that the current to the load never increases beyond a certain set limit, as calculated through a limiting resistor.
When 0.65V is fed into the base of the BC547 transistor, it turns on. Once it turns on, current flows from VCC down to the base of the BC557 transistor. This, in turn, turns on the BC557 transistor. Current now flows from the collector of the BC557 in 2 directions.
What should the input capacitor be set to in a transistor?
All that remains is the input capacitor to remove any DC offset on the input signal and keep our circuit stable. Let’s just set it to 1 uF. Remember from our transistor theory that the transistor will not switch on without a lower limit voltage push, and this is approximately 0.6 V for silicon-based circuits. We need to add bias resistors.
How many transistors are used to form a latch circuit?
In this circuit, we will use 2 transistors to form a latch. These are the BC547 transistor and the BC557 transistor. It will be explained in detail how this circuit works below. The BC547 is a BJT NPN transistor. The BC547 can handle a maximum voltage of 65V at its collector.
