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Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteThe LM317 is an adjustable linear regulator: it holds about 1.25 V between its OUT and ADJUST pins, while two external resistors set the output voltage. In Multisim, you can verify the circuit, sweep the adjustment resistor, find the input-voltage headroom needed for regulation, and inspect startup or load changes. The simulation is only as good as the selected SPICE model, however; it does not by itself prove safe temperature, stability, or hardware performance.
This guide covers NI Multisim desktop and the browser-based Multisim Live workflow. Multisim Live’s published circuit page currently carries a shutdown notice for September 15, 2026, so use desktop Multisim or another supported simulator for a long-term project: Multisim Live LM317 example.
How the LM317 circuit works
The LM317 is a positive, adjustable linear regulator, not a switching converter. It regulates the voltage from OUT to ADJUST at approximately 1.25 V. A resistor from OUT to ADJUST and another from ADJUST to ground then establish the output. TI lists the LM317 with an approximately 1.25–37 V adjustable range, a 1.5 A device rating, a 40 V maximum input rating, current limiting and thermal overload protection, and an approximately 2 V typical dropout figure. Those are device specifications, not guarantees for every package, temperature, load, or heatsink: TI LM317 specifications.
Because it is linear, the regulator turns excess voltage into heat. Estimate dissipation with PD=(VIN-VOUT)IOUT. At 24 V in, 12 V out, and 0.5 A, the device must dissipate 6 W—enough to require a thermal design in real hardware even if the simulated voltage looks perfect.
#1 Best Overall
- 3PCS LM317 Adjustable Voltage Regulator Power Supply LM317 DC-DC 4.2-40V To 1.2-37V Step Down Buck Converter Board Module
- Adjustable output voltage range: 1.2 ~ 37V
- Voltage Input: 4.2 ~ 40 V
- Output Current: 1.5A (min), 2.2A (typ)
- Size: 3.5x2.1x1.7cm(approx)
Wire the correct schematic
Vin ── IN LM317 OUT ─────── Vout ── RL ── GND
│ │
└─ ADJ ─ R2 ───┘
OUT ───────── R1 ── ADJ
In the actual schematic, connect R1 from OUT to ADJ, R2 from ADJ to ground, and the load resistor from OUT to ground. Connect the negative terminal of the DC source to the same ground node. Add a voltage probe directly from Vout to ground. Verify the symbol’s pin labels in Multisim rather than relying on the visual orientation of a physical package; pin order varies by symbol and package.
Calculate resistor values
The more complete relationship is:
VOUT=VREF(1+R2/R1)+IADJR2
Using the introductory approximation VREF≈1.25 V and initially ignoring adjustment-pin current:
R2=R1(VOUT/1.25−1)
A common starting value is R1 = 240 Ω, which draws about 5.2 mA through the reference resistor.
Rank #2
- Wide Voltage Range: This voltage regulator module support convert DC 3-30V or AC 3-20V input to adjustable 1.25V-28V output for versatile power supply needs
- Precise Voltage Control: The converter board equipped with duplex potentiometer for effortless and accurate voltage adjustment to match your specific requirements
- Digital Voltage Display: Features digital display voltage function, integrated digital voltmeter provides real-time output monitoring ensuring precise voltage settings for your experiments
- Efficient Heat Dissipation: This voltage regulator module with special-shaped heatsinks effectively manage thermal performance maintaining stable operating under 2A load conditions
- Compact and Versatile Design: Measuring 2.7 x 2 in this converter board offers easy installation and compatibility with various electronic equipments
| Target output | R1 | Calculated R2 | Practical choice |
|---|---|---|---|
| 5 V | 240 Ω | 720 Ω | 720 Ω |
| 9 V | 240 Ω | 1.488 kΩ | 1.5 kΩ |
| 12 V | 240 Ω | 2.064 kΩ | 2.0 kΩ or 2.05 kΩ |
| 15 V | 240 Ω | 2.64 kΩ | 2.7 kΩ |
| 24 V | 240 Ω | 4.368 kΩ | 4.3 kΩ or 4.4 kΩ |
For tighter accuracy, include the adjustment-current term and resistor tolerances using the selected device datasheet. A large R2 makes the adjustment-current error more visible.
Use a potentiometer safely
Replace R2 with a potentiometer to vary the output:
OUT ─ R1 ─ ADJ ─ potentiometer ─ GND
- Use a fixed series resistor or another fixed minimum-resistance arrangement to limit the maximum output.
- Set the output before connecting a sensitive load.
- Wire the potentiometer as a rheostat or divider exactly as intended; a miswired wiper can leave the adjustment node open.
- Keep a defined load connected during tests. Very light load can make a model’s result differ from the simple equation.
Build the circuit in desktop Multisim
- Open a new schematic and choose Place » Component.
- Search the component browser for LM317. Library names differ by edition and installed database.
- Place a DC voltage source, R1, R2 or a potentiometer, a load resistor, and ground.
- Open each component’s properties and enter the source, resistor, and load values.
- Inspect the LM317 properties to confirm the model and IN, OUT, and ADJ pin labels.
- Wire the OUT–ADJ–ground network, source negative, and load as shown above.
- Place a voltage probe on Vout relative to ground, then start interactive simulation.
NI documents the component-placement path and Multisim’s SPICE-based workflow in its Multisim introduction. Exact analysis availability depends on the edition.
Rank #3
- 1. Versatile Voltage Conversion：Easily transform 110V input into a precisely adjustable output ranging from 1.25V to 12V, maximum current 200mA, catering to a wide array of electronics projects, from small - scale circuits to power - hungry components.
- 2. Hands - on DIY Experience：Designed for electronics enthusiasts and DIYers, this soldering kit offers an engaging learning opportunity to understand voltage regulation principles while creating a functional voltage regulator.
- 3. High - Quality Components：Built with premium LM317 voltage regulators and durable parts, ensuring stable performance, low power consumption, and long - term reliability for your projects.
- 4. Simple Soldering Process：With a user - friendly design, even beginners can complete the assembly smoothly. Clear instructions are included to guide you through each soldering step.
- 5. Cost - Effective Solution：Save money on purchasing multiple voltage sources. This single adjustable kit meets various voltage needs, making it an essential addition to your electronics toolkit.
Open or recreate it in Multisim Live
You can inspect the public LM317 circuit example and recreate its topology in the browser editor. Community circuits are demonstrations, not manufacturer-validated reference designs. The service’s announced September 15, 2026 shutdown means it should not be treated as a durable cloud workflow.
Verify the output
Interactive measurement
- Place a voltage probe directly on the output node.
- Use the common ground as the reference.
- Run the simulation and read Vout.
- Increase R2 and confirm that Vout generally rises until input headroom, device limits, or the model prevents further regulation.
NI’s probe workflow supports voltage, current, and power measurements and can plot supported probe variables in Grapher: Multisim probes and Grapher.
DC operating point
- Choose Simulate » Analyses » DC Operating Point.
- Select V(out), and optionally input current, load current, and resistor currents.
- Add the variables to the selected list and click Simulate.
- Read the result in Grapher View.
This gives a steady-state bias point for the selected model and circuit conditions. See NI’s DC operating-point procedure.
Rank #4
- Input voltage range: DC5V-38V, AC5V-24V Output voltage range: DC1.25V-30V (continuously adjustable)
- Output current range: Maximum continuous working current <600mA (pressure difference does not exceed 10V), when the pressure difference exceeds 10V, please ensure that the output current is <400m
- Operating temperature range: 0°C-100°C (in order to prevent over-temperature damage, you can increase the heat dissipation by yourself or use other active heat dissipation methods).
- As an voltage regulator, LM317 has the characteristics of high stability, high temperature resistance, high linearity, etc. The output voltage range can reach 1.25V~37V continuously adjustable, and the maximum operating current exceeds 1A (using a large radiator orActive cooling measures).The board has a rectifier bridge and a 1000uF filter capacitor, which can effectively reduce the output ripple and interference.
Sweep input voltage to reveal dropout
- Choose Simulate » Analyses » DC Sweep.
- Select the input voltage source and enter start, stop, and increment values—for example, 0 V to a suitable upper limit in 0.5 V or 1 V steps.
- Select V(out), then run the analysis.
- Identify where the output stops tracking its target as input voltage falls.
That transition is not a universal dropout voltage. It depends on output current, temperature, device variant, package, model, and tolerances. NI describes the procedure at DC Sweep analysis.
Sweep R2 or the adjustment control
- Keep VIN comfortably above the desired output.
- Choose Simulate » Analyses » Parameter Sweep.
- Select the R2 value or potentiometer parameter and define a safe minimum, maximum, and increment.
- Use DC operating point as the swept analysis and plot V(out).
NI’s Parameter Sweep procedure supports device or model parameters with DC operating-point, AC, transient, and nested analyses.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Use transient analysis for startup and load changes
Apply a time-varying input or switch to create an input step, and use a transient analysis with a probe on Vout. You can observe startup, settling, input steps, and load steps. A transient plot does not prove real-world stability unless the exact regulator model, capacitor values, equivalent series resistance, wiring, and simulation settings represent the hardware.
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- Input voltage: 4.2 ~ 40 V
- Adjustable output voltage range: 1.2 ~ 37V
- Output current: 1.5A
- Applications Mobile phone, MP3, MP4, PSP and many other charging equipment
- 12 PCS LM317 Linear Regulator DC Buck Module
Capacitors and model limits
Capacitor requirements depend on source impedance, distance from the input filter, ripple, transient needs, and the selected datasheet configuration. TI notes that capacitors may be unnecessary when the regulator is close to input filter capacitors, while input bypassing, output capacitance, or adjustment-pin bypassing may be useful in other arrangements. Enter the actual capacitor values and ESR assumptions in the simulation; do not assume any capacitor is universally stable. The selected SPICE model may omit layout, parasitic, thermal, or protection behavior. NI explains the simulation-model boundary in its simulation fundamentals.
Troubleshoot common failures
| Symptom | Likely checks |
|---|---|
| No simulation or floating-node error | Add one valid ground; connect source negative; remove floating nodes and invalid sources. |
| Output near 1.25 V | Check for ADJ grounded, missing/shorted R2, wrong pin mapping, or insufficient input voltage. |
| Output too high | Verify R2, potentiometer wiring, measurement reference, and adjustment-current effect. |
| Output collapses under load | Check dropout headroom, load current, current limiting, source resistance, and power dissipation. |
| DC operating point fails | Remove ideal-source conflicts and zero-ohm paths, add realistic series resistance, simplify the circuit, or use nodesets and convergence remedies. |
| Simulation differs from the equation | Account for IADJ, resistor tolerance, model assumptions, load level, and device operating limits. |
For convergence-specific remedies, see NI’s DC operating-point troubleshooting guide.
Before building real hardware
- Check the selected package pinout and the exact datasheet.
- Confirm input-to-output differential and dropout margin at the intended current.
- Calculate
PDacross worst-case input, output, and load conditions. - Choose a heatsink, PCB copper area, and ambient-temperature limit for the package.
- Use resistor and capacitor tolerances, stated ESR, and appropriate protection components.
- Remember that the 1.5 A rating is conditional on package, temperature, current limiting, and thermal design.
- Validate the assembled circuit with a multimeter and oscilloscope.
If the voltage drop and load current make heat unacceptable, a switching regulator is generally more efficient than an LM317 linear stage.
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