AMS1117 Breadboard Power Supply Units: Reliability, Heat Issues, and Regulation Quality

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#1 21682998 16 Jul 2019 20:24

Michelle OBrien Michelle OBrien

Anonymous

Post #1
21682998 16 Jul 2019 20:24

Those handy little Breadboard Power Supply units: the ones where the pins fit snugly into the NEG (-) and POS (+) rails on both sides at one or other end of the average breadboard. Input voltage to the unit 6V-12V (DC): output voltage from the unit to the breadboard 3.3V or 5V (jumper pins decide which): maximum output current 1A: very cheap, can be obtained in the UK for under 2.50 GBP.
Are they sufficiently regulated for providing power to chips on breadboards in prototyping projects? Are they any good? They can get very hot . The circuitry includes an AMS1117 voltage regulator. I’ve had two burn out on me, whereas my Arduino board happily gives a regulated 3.3/5V for the stuff on the breadboard with no sign of stress.
Michelle O’Brien 
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#2 21682999 16 Jul 2019 21:45

Elizabeth Simon Elizabeth Simon

Anonymous

Post #2
21682999 16 Jul 2019 21:45

Michelle,
The problem you are having with the cheap breadboard power supply units is that the regulator used is a linear regulator which is inefficient and will get warm (if not hot) in use. A while back I wrote a column explaining how this works.
https://www.eeweb.com/profile/elizabeth-simon...es/how-to-read-data-sheets-linear-regulatorsI also did a follow-on on getting more power.https://www.eeweb.com/profile/elizabeth-simon/articles/how-to-read-data-sheets-linear-regulators-more-power

Taking a glance at the AMS1117 datasheet here, I see that the best thermal resistance (lower is better) is 55C/W from junction to ambient. If you have 9V in and want 5V out at 100 mA, the regulator will dissipate 400mW and the temperature will go up by 22C. If you try to get 1A, the temperature will try to go up by 220C and the regulator will fail.To answer your other question, the output should be plenty stable enough to power chips with provided that you stay within it's thermal limits.My guess is that the cheap supplies don't have a good layout for thermal efficiency so you may be getting a temperature rise closer to 80C/W. Advertising these things as 1A regulators is misleading in my opinion.
#3 21683000 16 Jul 2019 21:58

Conrad Mannering Conrad Mannering

Anonymous

Post #3
21683000 16 Jul 2019 21:58

Hi,I have several of these and have powered Atmel chips without much problem. I do note they specify on e-bayIncludes:AMS1117 12V to 5.5V/3V 1A Linear RegulatorLarge BreadboardJumper WireFreature of AMS1117 12V to 5.5V/3V 1A Linear Regulator:• Dual Channels• Input Voltage Operating Range: 6.5V - 12V• Output Voltage Options: 0V, 3.3V, or 5V• Maximum Output Current: 700mA• DC Adaptor Powered or USB Powered• Two Independent Controlled Output• Overheat Thermal Shutdown• Short Circuit Protection• Breadboard CompatibleI have to say that I have not stressed them to the max current level so far and I usually only drive them with enough DC input to get the rated output I need.They may be expensive but over the years a good solid bench power supply will give good service.Some times a good second hand comes up on E-bay that's where I got my dual Thandar from.I have also been using link to power supply module on e-bay these have proved to be great when supplied from a suitable laptop PC power block. They look neat and if you can afford the cost of two a great home brew dual power supply that can easily be put in a suitable box with terminals to connect to.
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#4 21683001 17 Jul 2019 00:21

Rick Curl Rick Curl

Anonymous

Post #4
21683001 17 Jul 2019 00:21

Hi Michelle-I agree with Elizabeth about the heat dissipation and the stability, but I would like to add that if you attach a heatsink to the regulators you can keep the temperature down and possibly avoid future failures. It doesn't have to be very big- a little 8mm x 8mm or 10mm x 10mm extruded aluminum heatsink will help a lot. Attach it with thermally conductive adhesive. There is a silicone-based adhesive sold on eBay as "Heatsink plaster". I have used it and its cheap and works well. -Rick
#5 21683002 17 Jul 2019 04:56

Duane Benson Duane Benson

Anonymous

Post #5
21683002 17 Jul 2019 04:56

I have used several of these from Adafruit. I haven't put a scope on them, but I've used them for a lot of projects at 3.3 volt, 5 volt and the variable volt setting. I've powered microcontrollers directly, sensors, and development boards. I usually use a 9 volt input supply and sometimes will put a heat sink on the regulator. I don't know that I've ever drawn more than about 600 mA from one. I've never had one fail.
#6 21683003 17 Jul 2019 07:24

David Ashton David Ashton

Anonymous

Post #6
21683003 17 Jul 2019 07:24

Seems to me there would be a good case for making one of these devices but using a switching regulator (the good old 34063 would be a good choice) so it can supply a bit more current without overheating.
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#7 21683004 17 Jul 2019 12:56

Joe Farr Joe Farr

Anonymous

Post #7
21683004 17 Jul 2019 12:56

In the past I made a couple of these boards using standard 7805 type TO220 regulators on bits of Veroboard (these days I prefer my multi-output bench PSU). But you can now get complete switching regulators, built on a TO220 style PCB and available in different voltages. https://www.ebay.co.uk/itm/Switching-Voltage-Regulator-3-3V-1A-TO-220-7805-pinout-Replaces-LDO/264228752107?epid=12030258612&hash=item3d8542caeb:g:s88AAOSwtOZchYmv
You could probably use these to replace the existing linear regulators on those boards. What I've also found really useful are the boost voltage regulators. https://www.ebay.co.uk/itm/Boost-Voltage-Regulator-Converter-Step-up-Power-Supply-DC-3-3V-3-7V-5V-6V-to-12V/272666687043?hash=item3f7c337643:g:wsMAAOSw7GRZE9umThese aren't much bigger than a TO220 but can step-up a DC voltage. Great for battery power applications, and I've started using these when I refurbish Texas Instruments calculator battery packs. Regards,Joe
#8 21683005 17 Jul 2019 14:05

Michelle OBrien Michelle OBrien

Anonymous

Post #8
21683005 17 Jul 2019 14:05

Are we in danger of straying a bit off topic? I'm talking about one of these. I like the way they fit tidily and firmly on to the end of a breadboard so they don't slide about or risk coming loose. But are they reliably up to the job regulated power-wise is what I'd like to know.
Michelle
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#9 21683006 17 Jul 2019 16:04

Conrad Mannering Conrad Mannering

Anonymous

Post #9
21683006 17 Jul 2019 16:04

Thought you were writing about these uints. They look the same as the ones I have and I have had no problems in using them. Just take note of what Elizabeth and Duane have said.
#10 21683007 17 Jul 2019 18:56

Justin Spencer Mamaradlo Justin Spencer Mama...

Anonymous

Post #10
21683007 17 Jul 2019 18:56

I made a couple of boards too with 7805s and never had any of them fail.If in doubt of power rating or current ability (as Ms.a Elizabeth wrote - we have little means of ascertaining the credibility of the advertised current rating because it may have been measured with a fast load sweep at typical temp. or with a pulsing load) and if the application isn't that exacting, I'd opt to just shunt the regulators - or in Ms. Michelle's case, shunt 2 of those cheap breadboards.
#11 21683008 18 Jul 2019 00:29

Joe Farr Joe Farr

Anonymous

Post #11
21683008 18 Jul 2019 00:29

Assuming the components are to specification, which is by no means certain, then the voltage regulators have thermal and short-circuit protection, so assuming you don't exceed the working voltage of the regulators and capacitors, or accidently connect the input power backwards, there's no reason why these boards won't give you many years of useable service. The components most likely to fail in service (since there are so many fakes around) are the capacitors, or dry joints around the connectors if you are a bit rough with them.Regulation wise, the output should be fine as long as the input DC is smoothed adequately and there isn't too much switching noise if you are powering the boards from a SMPS.
Joe
#12 21683009 09 Apr 2021 15:05

AlanE AlanE

Anonymous

Post #12
21683009 09 Apr 2021 15:05

i have bought 2 of these type of units, both had failures.
First unit had a shorted 5v regulator, shorting across the vin and vout sending 12v down my rails AND out the usb output that you are supposed to be able to use to power a usb device. Which can only increase the draw on the regulator.
2nd unit had the same short across the 5v regulator and the 3.3v regulator.

Very bad QC i suppose coming out of CN. They look super handy, which is why i got some. you might be better building your own bench supply out of an old atx power supply or something like that if you don't want to buy a bench supply.

you can actually get reasonable cheap bench supplies with less features from CN.I have an NPS-1601 clone that i got pretty cheap and it works a treat.

You could always strip back the breadboard and solder up a couple of cables to go back to the bench supply so you still have the nice rails connectors on your board.

Or given that it is just shorting the input voltage straight through i could just make a cable with the barrel connector on one end and bananas on the other to go into my bench supply!
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Topic summary

✨ AMS1117-based breadboard power supply units provide regulated 3.3V or 5V outputs from 6-12V DC inputs and are popular for prototyping due to their compact form factor and low cost. These units use linear voltage regulators (AMS1117), which inherently dissipate heat proportional to the voltage drop and current load, often causing the regulator to become hot or fail if operated near their 1A maximum rating without adequate heat sinking. The AMS1117 regulator offers thermal and short-circuit protection but has a thermal resistance around 55°C/W, limiting safe power dissipation. Users report stable voltage regulation suitable for powering microcontrollers and sensors when operated within thermal limits and current ratings (typically below 700mA to 1A). Adding small aluminum heatsinks with thermally conductive adhesive can significantly reduce regulator temperature and improve reliability. Some users have experienced regulator failures due to poor quality control, including short circuits between input and output rails, which can damage connected devices. Alternatives suggested include using switching regulators (e.g., based on the 34063 IC) or replacing linear regulators with switching modules to improve efficiency and reduce heat. Bench power supplies or modified ATX power supplies are recommended for higher current or more reliable operation. Capacitor quality and proper input smoothing also affect output stability. Overall, AMS1117 breadboard power supplies are adequate for low to moderate current prototyping but require careful thermal management and quality consideration.
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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]

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