Often the many op-amps have this problem. They need a split supply. The output terminal has positive, negative, and ground. But most power supplies have only a single output (positive and negative). So, you cannot use them to power op-amp circuits.
Do not worry about this problem. You can just build the power supply like this. It will change the input voltage into the dual rail.
How Power Supply Splitter works
The main idea, it splits input voltage in half, two equal output. Which it has a ground, is midway between the positive and negative supply voltages.
The ground has to be a regulated voltage. And it powers a suitable current to load.
Figure 1 block diagram shows special two-way voltage regulator for load 1 and Load 2.
If Load 1 and Load 2 uses equal currents. And, the voltage across them is still halfway. So the regulator do not change.
If the currents of 2 loads are different. Then, either Q1 or Q2 will conduct extra current to make up the difference.
Figure 2 Shows the circuit. R1 and R2 divide the input voltage.
An OP-AMP-IC1 produces a regulated voltage at the “ground” output terminal. Then, either Q1 or Q2 conduct as necessary.
Both capacitors C1 and C2 keep the output voltage when the load changes suddenly.
Diode D1 protects the reversed polarity of the main power supply.
The turn-on voltages of Q1 and Q2 are 1.2 volts. So this may be a problem, dead zone. The output of IC1 must cross in order the catch up with an unbalanced load.
But this problem is little for IC1. It can cross the dead zone very fast.
In real testing. This circuit has a good regulator to power the OP-AMP circuits. And also other loads such as buzzers and flashing light bulbs.
Parts List for the power-supply splitter
IC1-LM741 operational amplifier,
Q1-2N3055 100V, 15A, NPN transistor
Q2-MJ2955 100V, 15A, PNP transistor
D1— 1N5402 (3A,50-PIV rectifier diode)
Additional parts and materials
R1, R2— 10K, 1/4 watt, 5% resistor
C1,C2—100uF, 25V, electrolytic capacitor
Enclosure, binding posts, circuit board, solder, wire, the optional heat sink for Q1 and Q2, etc.
Because there are so few components, a printed-circuit board is not necessary.
We can assemble the smaller components (D1, R1, R2, and U1) on a universal PCB Board.
Should put capacitors C1 and C2 close the output terminals.
The cheap 741 IC is the best OP-AMP. If we use higher performance OP-AMPS such as the TL081. It cannot improve the performance of the circuit.
How to use its
You can use the splitter with fixed- or adjustable voltage power supplies. The ranging from 8 to 30 volts. Make sure, it is an isolated power supply.
This splitter can handle at least 250 mA at a 30-volt input.
The specified transistors and proper heat sink, this splitter can handle many amps.
If you do not have 2N3055 and MJ2955. But you have TIP41 and TIP42 or smaller size. You can use the circuit below.
Simple Supply Splitter circuit
If you must modify a normal power supply or usual to dual power supply positive, negative, GND(0V). I introduce to try use. Circuit Supply Splitter with IC 741& TIP41,TIP42. When seeing the detail in the circuit make the output of the circuit is pin GND(0V) the part is pin positive be +V part negative be -V there.
When Transistor TIP41 and TIP42. Then make the circuit pays current get 100mA does not exceed which enough for normal using.
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