Here is LM338 Adjustable DC power supply circuit, 1.2V to 30V. It can provide a current maximum to 5A and 10A. If you have used LM317 or LM350. They are similar, so easy to use with a few components. But LM338 have higher a current than LM317. You can look at a datasheet below more spec.
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The LM138/LM238/LM338 are adjustable 3-terminal positive voltage regulators capable of supplying in excess of 5A over a 1.2V to 32V output range.
They are exceptionally easy to use and require only 2 resistors to set the output voltage.
The careful circuit design has resulted in outstanding load and line regulation comparable to many commercial power supplies.
The LM138 family is supplied in a standard 3-lead transistor package.
- 7A Maximum output current
- 5A output current
- Adjustable output 1.2V to 37V
- Line regulation typically 0.005% /V
- Line regulation typically 0.1%
- Thermal regulation
- Current limit constant with temperature
PINS of LM338K To-03 and LM338T TO-220
1.2-30V, 5A Variable power supply using LM338
We may have many ways such as: to modify the LM317 Variable Regulator 0-30V 1A. By adding the power transistor MJ2955 in a circuit. As following Adjustable Voltage and current regulator IC power supply . Or You may build the Variable dc regulator 0-30V 5A circuit, as well. But these methods. Rather cumbersome and wasting too more money.
However, we can build this circuit easily and cheap, By using the packages IC No. LM338 only one, Similar to the LM317 IC number, but it can supply up to 5A, like the circuit shown in Fig.
How this circuit works
The transformer T1 converts the AC 220V to 24 Vac, so be rectified the current by the bridge diode rectifier BD1 – 10A 400V. Until DCV has come out that the filter capacitor C1 is equal to 35 volts.
The IC1 is the heart of the operation of this circuit. By the voltage output value obtained from the IC depends on the voltage value at the Adj pin of IC1, or can be varied by adjusting the VR1.
However, the output voltage will be approximately equal to 1.25+1.25VR1/R1
The output voltage at the output pin of the IC1 is a more powerful filter with the capacitor C3.
Parts you will need
IC1: LM338K, LM338P
D1: Bridge Diode 10A
D2, D3: 1N4007, 1000V 1A diode
R1: 220Ω 0.5W resistors 5%
R2: 12K 0.5W Resistors 5%
VR1: 10K Potentiometer
C1,C3: 4700uF 50V Electrolytic
C2: 0.1uF 50V
T1: Transformer, 24V 5A secondary
You must solder all devices in the PCB to completely, for the IC LM338K should install with a large heat sink. and all device has the poles. Caution connected the correct, especially electrolytic capacitor.
Figure 2 The PCB layout and components layout
Because IC number is high price.You may use the LM317 and transistor, to expand the current demand.
Click HERE >>> Best DC power supply 3Amp to adjust 1.2V-20V & 3V-6V-9V-12V add transistor 2N3055 parallel from 3A to 5A easily.
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1-20V, 10A Adjustable DC Power Supply
1.2V-20V 10A adjustable dc power supply using LM338
If you want Variable Regulate Power Supply high current more than 10A up. I would recommend this circuit. Because build easy, use LM338 and LM107 again.
The normal LM338 have current about 5A. Then, must use 2 pcs. It causes more current up to 10A. The VR1 adjusts an output voltage of 1.2V to 20V cover usual usability. This idea can protect all error with two LM338.
If you want to see examples of projects. Using LM338 to multiple connections in parallel. To boost the higher current. Click: High power supply regulater 0-30V 20A using LM338
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