FAQ
TL;DR: AMS1117 boards run hot: best-case 55°C/W; at 9V→5V and 100 mA they dump 0.4 W. “Advertising these things as 1A regulators is misleading.” [Elektroda, Anonymous, post #21682999]
Why it matters: If you prototype MCUs or sensors, heat limits current and reliability, so you must size input voltage, cooling, and load correctly.
Quick Facts
- Typical specs: 6.5–12 V input, jumper-select 3.3 V or 5 V, often marketed ≤700 mA. [Elektroda, Anonymous, post #21683000]
- Thermal math: 55°C/W junction–ambient; 0.4 W adds ~22°C rise. [Elektroda, Anonymous, post #21682999]
- Real-world use: many projects at 3.3/5 V, ~≤600 mA, no failures reported. [Elektroda, Anonymous, post #21683002]
- Protections exist, but component quality varies; good input smoothing helps regulation. [Elektroda, Anonymous, post #21683008]
- Edge case: regulator shorted, passed full 12 V to rails and USB on some units. [Elektroda, Anonymous, post #21683009]
Are AMS1117 breadboard power supplies good enough for chips?
Yes, when kept within thermal limits. The linear regulator holds output stable if you avoid overheating. Use proper input voltage and do not chase the headline “1A.” This keeps microcontrollers and logic ICs within safe margins during prototyping. [Elektroda, Anonymous, post #21682999]
Why do these boards get so hot?
They are linear. Heat equals (Vin − Vout) × I. At 9 V in, 5 V out, and 100 mA, the regulator burns 0.4 W. With ~55°C/W thermal resistance, that is ~22°C rise, and much higher at larger currents. Push 1 A and the device overheats or fails. [Elektroda, Anonymous, post #21682999]
How much current can I realistically draw?
Keep well below the advertised 1 A unless input–output voltage is tiny and cooling is excellent. At 9 V→5 V, 1 A implies a 4 W drop, which exceeds safe dissipation on these small boards. Users commonly stay ≤600 mA to avoid trips and failures. [Elektroda, Anonymous, post #21683002]
What input voltage should I choose for 5 V or 3.3 V output?
Use the lowest input that still meets dropout margin to cut heat. Many users feed only what is needed for the selected output, rather than a full 12 V. That simple choice improves reliability and keeps fingertips safe. [Elektroda, Anonymous, post #21683000]
Do tiny heatsinks actually help on AMS1117 boards?
Yes. A small 8×8 mm or 10×10 mm aluminum heatsink attached with thermal adhesive reduces junction temperature and can prevent shutdown. “Heatsink plaster” silicone adhesive works and is easy to apply. It is a cheap, quick win. [Elektroda, Anonymous, post #21683001]
Are there proven success stories with these modules?
Yes. Several builders powered microcontrollers, sensors, and dev boards at 3.3 V and 5 V, often from a 9 V source, sometimes with a small heatsink. Reported current was about 600 mA or less without failures. [Elektroda, Anonymous, post #21683002]
What failure modes should I watch for?
Quality control varies. Some units failed with the 5 V or 3.3 V regulator shorted, backfeeding full input (e.g., 12 V) into the rails and even the USB port. Treat unknown units cautiously and test before powering valuables. [Elektroda, Anonymous, post #21683009]
How clean is the output voltage for digital logic?
Regulation is fine if you stay within thermal limits and use a smooth DC input. When powering from a switching adapter, ensure adequate filtering to keep switching noise off the rails. Good capacitors matter here. [Elektroda, Anonymous, post #21683008]
Is a bench power supply a better investment?
For flexibility and reliability, yes. A bench PSU serves many projects, supports current limiting, and avoids breadboard thermal constraints. Some users buy new or second‑hand units and route the rails from the bench supply. [Elektroda, Anonymous, post #21683000]
What are switching-regulator alternatives to AMS1117?
A switching design, such as one built around the MC34063, improves efficiency and current headroom. It reduces heat at the same load because it does not burn off voltage as heat. This suits higher-current breadboard work. [Elektroda, Anonymous, post #21683003]
Is there a drop‑in replacement for the linear regulator?
Yes. TO‑220‑pinout switching‑regulator modules exist in fixed 3.3 V and 5 V options. They can replace a 7805‑style LDO footprint and deliver more current with less heat, useful for retrofits and compact builds. [Elektroda, Anonymous, post #21683004]
How do I keep my board from overheating? (3 steps)
- Use the lowest input voltage that meets dropout for your chosen output.
- Add a small 8–10 mm heatsink with thermal adhesive.
- Keep current modest; avoid long runs near the claimed maximum.
[Elektroda, Anonymous, post #21683001]
Can I parallel two boards to share the load?
For non‑critical builds, some users shunt regulators or parallel two cheap boards to spread current. This is a workaround when ratings seem optimistic, but monitor heat and matching carefully to avoid imbalance. [Elektroda, Anonymous, post #21683007]
What is the AMS1117?
AMS1117 is a low‑dropout linear voltage regulator commonly used on these breadboard power modules to provide 3.3 V or 5 V from a higher DC input. It is simple but dissipates heat proportional to voltage drop and load current. [Elektroda, Anonymous, post #21682998]
What is the MC34063?
MC34063 is a classic switching regulator IC for buck, boost, or inverting converters. Using it in a breadboard PSU provides higher efficiency than an AMS1117, enabling more current with less heat in compact projects. [Elektroda, Anonymous, post #21683003]
