1.5V 1.8V 2.5V 3V 3.3V 3.7V 4.2V to 5V DC-DC Step Up Power Module Voltage Boost Converter Board 0.9-5V to 5V 5PCS

Works well, however it takes about a quarter of a second for voltage to fall off when boosting 0.8V to 5V. This can be fixed with a pull down resistor.I am using this to take a 0.8V signal and boost it to 5V so that an arduino can trigger off the 5V signal (input must be over 3V for arduino to read high). The thing I'm measuring rotates up to 6k RPM so I need a signal to go from on to off in a few milliseconds. The voltage would not fall off quick enough on this for the arduino to read low before the next cycle starts, so I had to add a 1k pulldown resistor between ground and the 5V line so that the voltage falls off quick enough. Now works great with this addition. Nothing is getting noticeably hot.I haven't ran this for any meaningful time so no telling if it'll last, but so far this is a cheap simple solution to triggering arduino with low voltage levels.

I use these to boost the voltage on several d-cell flashlights when used with led bulbs.Tight fit but it can be done.

Didn't quite work, but that's because I had too much current draw. The modules output 5v as described, I was just pushing them too hard. I will be using them in other projects though.

Converts 2.8v flawlessly to 5v in my application. I've used two so far no problem

I used these devices (I am not using them any more) to take power from an 18650 battery and generate 5V for target devices.They are super-simple to use (just 3-wires), and they worked well out of the box. The 5V is stable and clean (add a few caps, downstream, of course).They are not at all efficient. Best case, when the input voltage is 4.5V+ (fully charged battery), they yielded about 84% efficiency. However (and this dramatic a drop was surprising to me), the efficiency drops as the input voltage drops. With 2.8V going in (like when a battery is nearing exhaustion), the efficiency is 44%. Around 2.8V they get a little wonky and won't up-convert voltage much below that.So this means that as your battery drains, the efficiency drops, requiring more and more power from the battery to satisfy a constant load, for example. It's an accelerating cycle that drains the battery really quickly.That's too bad, since these are tiny, easy to deploy units with a relatively clean output. They're kind-of battery killers, though. Modern DC/DC converters should be able to maintain 90%+ efficiency over their full range of input voltages.For non-battery powered applications where power does not matter, or your load is very, very light, and all you need to do is convert a voltage between about 3V-5V to a stable 5.0V output, they'd probably be OK.

I bought these to use with 3.7-4.2 V lithium ion batteries for projects where I needed 5V to run older electronics, specifically liquid crystal displays (LCDs). They are really tiny and easy to add to even the smallest project box. They have a significant current capability, but all of my applications are in the battery-operated, micro power range. Without an illuminating LED, most LCDs are in the sub-milliamp range unless updated at high rates. This boost converter uses a small inductor to generate a voltage above the input voltage. By themselves, these controllers draw a minimum no-load current of a few milliamps. I added a 2.5 mH hand-wound toroid inductor to the input wire to augment the inductance on the board, along with a 100 uF capacitor on the output for noise filtering. This dropped the no-load operating current to a fraction of a milliamp. That allowed using the LCD with about a milliamp of added current draw to the battery. There are probably a lot of other applications for these that involve higher currents, but small size and the possibility of very low quiescent current was why I bought them.

All 5 boosters worked just fine. Tested them as a Joule Thief with a green LED and 5.1K series resistor (draws around 0.5mA at 5V) as a load. All boosters managed to turn the LED on with as little as 0.52V on the input. And the maximum draw on the input was about 7mA which happens when the input voltage is on the low end (0.52V). At higher input voltages the input current to the booster is lower.

I am using these to drive arduinos from single lipos. These units must operate in the high audio range and students often complain that it hurts their ears. Some teachers can also hear this, with my hearing loss I am not able to. But it is hard to justify hurting children. This feels like a design flaw and not something I have found is easily mitigated.