Normally 78xx series ICs can be output currents for a maximum 1 A, or in the common usage, it is only up to 0.6A. But we need more boost current up, how to do next?
Boosting Regulator Current using transistor
In this increasing Regulator Current or circuit, the power transistor is used to provide most current to the load, to maintain a constant the voltage, by the little current still through the regulator IC intact.
Let’s say, I want a the 12V voltage regulator, and current output voltage at 5A, I must to use an IC No. 7812 and it can take a transistor number MJ2955 or TIP2955. The input voltage is enough I think that about 20V, which voltage drop across the transistor is approximately 8V. And it takes about 40Watt energy, which can be calculated = Vce * Ic. When is this. We need a cooling pad for Q1, which is large enough, it is very hot, may be cause damage.
If you want to add current to the IC 79xx or negative voltage, you can also easy to make, but simple NPN transistor type 2N3055 is only a number.
10A fixed regulated Supply using 78XX – MJ15004
Today a friend of me visits at a house. He leads old equipment come to give very plentiful and tell beg for DC power supply 10A circuit.
That be simple please , when I sees the equipment that him has had already. Then take this circuit see use 78XX integrated circuits. Have many the number and Transistor power number M15004 that can enhance current. Get tall arrive at 10A.
The important aspect is must use Transformer that be appropriate give current 10A More than. And use C-Filter 10000uF sizes go up with. The detail is other see in the circuit has leisurely sir.
Increase current of 7805
But above circuit not have protection over load
We need to use the below circuit!!
Sometimes we want to use. high current at a dc regulator 5v 3a. We can do this by using the voltage regulator IC1 positive constant number 7805.
The Q1-2N3792 and Q2-2N5956 of circuit will serve to increase current for IC regulator.The R2 acts as the anti-saturation of Q12N3792 and Q2-2N5956. Without R2 will allow the two transistors do not work.The output current can be from IC1 alone.R1 specify the bias current to IC1.And the current output of you against too much saturated with. The C1 functions in input power filter to smooth.And C2 serves to prevent interference with the pressure to pay out (Vout).
This circuit can help enlarge current of power supply circuit that use Ic regulator so well. you can use other IC 7805,7809,IC-7812,and IC7815.
Q1 is BFX88 or Equivalent
Q2 is BD132 or Equivalent
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