In this post LM723 IC is a handy chip that helps control voltage.
It gives a stable DC output and lets you change the voltage and current as you need.
This special regulator can set the output voltage anywhere between 2V and 37V.
It can provide up to 150mA of output current and can take in a maximum of 40V.
The High Current Adjustable Regulator Circuit is made to give out 30V at 3A, which is great for lab power supplies and different electronic projects.
The LM723 makes sure the voltage stays just right and if you add an extra pass transistor, it can manage even higher current levels better.
Circuit Working:
Parts List:
| Component | Value / Specification | Quantity |
|---|---|---|
| Resistors (1/4W unless specified) | ||
| Fixed Resistor | 680Ω | 1 |
| Fixed Resistor | 82k | 1 |
| Fixed Resistor | 1k | 1 |
| Power Resistor (5W) | 0.18Ω | 1 |
| Fixed Resistor | 8.2k | 1 |
| Fixed Resistor | 2.2k | 1 |
| Potentiometer | 10k | 1 |
| Capacitors | ||
| Electrolytic Capacitor | 10000µF 50V | 1 |
| Electrolytic Capacitor | 100µF 25V | 1 |
| Ceramic Capacitor | 100nF | 2 |
| Ceramic Capacitor | 470pF | 1 |
| Semiconductors | ||
| IC | LM723 | 1 |
| Transistor | MJ3001 | 1 |
| Diode | 6A6 | 2 |
| Bridge Rectifier Diodes | 6A6 6 amp | 4 |
| Transformer | 230V Primary, 25V Secondary, 5A | 1 |
The circuit begins with an input of 230V AC which undergoes several transformations the voltage is reduced, converted into direct current DC and then filtered to create a smooth DC output.
The LM723 component is responsible for maintaining a consistent output voltage while a powerful pass transistor called MJ3001 manages higher current demands.
A 0.18Ω resistor referred to as R4 plays a crucial role in monitoring current and providing overcurrent protection.
The feedback system consisting of resistors R5 and R6 helps determine the desired output voltage level.
Now let us go through the working of the circuit:
The transformer reduces the 230V AC to a lower AC voltage.
The bridge rectifier D1 converts the alternating current into pulsating direct current.
Capacitor C1 with a capacitance of 10000µF smooths out the DC voltage.
The IC1 LM723 receives the rectified and filtered voltage at pin 12.
The output voltage is adjusted by a voltage divider made of resistors VR1 and R1 at pin 5 and you can change the output voltage using the potentiometer VR1.
An internal error amplifier in the LM723 compares the reference voltage with the feedback from the output and makes necessary adjustments.
The MJ3001 transistor Q1 enhances the circuits current handling capability.
Resistor R4 monitors the current flow helping to prevent overloads.
Diodes D2 and D3 rated at 6A6 safeguard the circuit from voltage spikes and reverse polarity issues.
Capacitors C4 and C5 work together to keep the output voltage steady.
Formulas with Calculations:
Below are the formulas with calculations for High Current Adjustable Regulator Circuit with 30V 3A Output:
Output Voltage Calculation:
Vout = Vref × (1 + VR1 / R1)
where,
Vref = 7.15V Internal Reference of LM723
VR1 = 10kΩ, R1 = 680Ω
Vout = 7.15V × (1 + 10000Ω / 680Ω)
Vout = 7.15V × (1 + 14.7)
Vout = 7.15V × 15.7
Vout = 30V
Current Limit Calculation:
Ilimit = 0.6V / R4
where,
R4 = 0.18Ω
0.6V is the base emitter voltage of the pass transistor Ilimit = 0.6V / 0.18Ω
Ilimit = 3.33A
Thus, the circuit limits the maximum current to approximately 3A.
How to Build:
To build a High Current Adjustable Regulator Circuit with 30V 3A Output follow the below mentioned steps:
- Gather all the components as mentioned in the above circuit diagram
- Connect pin 2 of IC1 to the emitter of transistor Q1 through resistor R3
- Connect pin of IC1 to Vout of 2V to 37V
- Connect pin 4 of IC1 to pin 13 of IC1 through capacitor C3
- Connect pin 5 of IC1 through center leg of VR1 pot, lower leg of VR1 connect to resistor R1 and upper leg of VR1 connect to pin 6 of IC1
- Connect pin 10 of IC1 to the base of transistor Q1 and collector of Q1 transistor connect to positive terminal
- Connect pin 11 and pin 12 of IC1 to positive supply
- Connect resistor R4, R5 and R6 in series from emitter of transistor Q1 and GND
- Connect cathode of diode D2 to positive terminal and anode of D1 connect to junction of emitter Q1 and resistor R4
- Connect resistor R2 from positive supply and pin 2 of IC1
- Connect capacitor C4, C5 and diode D3 from pin 2 of IC1 and GND
- Connect capacitor C1 and C2 in parallels from one end of D1 bridge rectifier and GND
- Connect the secondary two ends of transformer to two end of bridge rectifier D1 end
- Connect one end of bridge rectifier to GND of the circuit
- Connect the primary ends of transformer to 230V AC input
Conclusion:
The High Current Adjustable Regulator Circuit with 30V 3A Output operates at 30V and 3A using the LM723 is a dependable power source for many uses.
It delivers a steady and adjustable voltage while offering overload protection and minimal ripple output.
The LM723s accurate regulation along with a pass transistor for handling higher currents, guarantees effective performance.
It is a great option for DIY electronics projects, bench power supplies and testing purposes.