Put the bag in, press the “popcorn” button, and the microwave oven knows precisely when to shut off.
How does it do this?
In this SDMB thread from 2005, Q.E.D. said the oven measures the humidity level in the chamber. I’m a bit dubious that this is how it works. RH sensors are not all that reliable or accurate. Plus I would think the RH level would get very high very quickly soon after the corn starts popping.
I’m thinking a more reliable method is to use an audio transducer (microphone) to count the popping rate (pops/second). Is this how it works?
I’m pretty sure some count the pops and others use their best guess for time. I’ve had microwaves that popped a perfect bag every time (apparently using some sort of sensor, I presume audio) but my current microwave, which is pretty good otherwise, will burn your popcorn if you just let the popcorn setting do all the work.
Ours is just a timer. You push the Popcorn button and the timer sets itself to 1.75 minutes, which is a strange measurement, and then you have to push the Start button.
I have no reason to expect that the popcorn button sets into motion a pop counter or any such thing. I also have no expectation that it will do anything but set the timer for the 1.75 minutes on high or whatever it is that typical popcorn packs suggest. Then I use my ears. Okay, I really use a cheap air popper and plain kernels. They’re foolproof and I can control the salt and use real butter.
I have had a few microwaves. All of them had only a timer for popcorn. I still prefer to make my own popcorn (without the bag), by putting popcorn kernels on a paper bag with some salt and oil. Works really well.
I’m wondering whether there could be a scale under the platter. Or isn’t there measurable time required for a larger bag, or is the number of kernels irrelevant?
Mine doesn’t appear to work by time. It doesn’t display a time until the last 15 seconds.
It doesn’t appear to work by sound, because the kernels are still popping regularly when the timer kicks in.
I think mine is a humidity sensor.
It works pretty good. I typically hit the 30 second button, then turn off by hand after an additional 10 seconds. The full 30 seconds burns, 20 seconds is too long, but 10 seconds squeezes out several more good pops.
Yeah, I could do it by time, too, but the popcorn button ends if I get distracted.
My microwave has a fairly accurate sensor. Back when I bought it and read the instruction book, it stated the sensor uses steam + what it’s set for to tell when something is done. It also had fairly specific instructions as to how to prepare certain items in order for the sensor to work well. For instance, disregard whatever instructions come with a frozen dinner, simply put a 2" slit in the center of the cellophane cover and then press the “frozen dinner sensor” button. Baked potatoes, pierce with a fork twice on opposing sides and then press the “baked potato sensor” button.
When I follow the instructions according to the microwave, stuff comes out perfectly. Frozen vegetables are perfect when covered with saran wrap with one small corner uncovered, but if I put them in uncovered it thinks they’re done when they’re still cold in the middle.
Microwave popcorn comes out perfectly. I’m quite certain the sensor is programmed to use a certain amount of steam as a trigger for the timer. As noted by another poster, when it’s set to “sensor cook” it doesn’t have the time displayed initially, it just scrolls “sensor cook” until it senses a certain amount of steam, and only when there’s a certain amount of time it has calculated to be left does it put a time countdown on the display. That countdown time is not consistent. It can be anywhere from 2 minutes to 15 seconds and doesn’t do the same final time for the same setting.
Perhaps. But many times I’ve made two bags of popcorn in quick succession. If the oven used an RH/T sensor, you would think the second bag would not pop correctly.
A timer would be the simplest approach. But the popcorn button works equally well for smaller and heavier bags.
Ours at home has three popcorn settings depending on the size of the bag. As you press the button, it cycles between, I believe, 3 ounce, 2.7 ounce, and 1.6 ounce sizes. Some of y’all should press your “popcorn” button more than once and see what happens.