WYPH Ultrasonic Module HC-SR04 Distance Measuring Ranging Sensor for Arduino UNO for Mega R3 Duemilanove Nano Robot Pack of 10pcs

This model of the HC-SR04 has performed well for an inexpensive sensor. There are a number of these HC-SR04's on the market, with at least 2 different chip layouts (I don't know how else to identify them). The "other layout" model has pretty consistently locked up or burned out when triggered too frequently. A class of 20 beginner students was unable to damage a single one of these. On the side of don't expect too much from an inexpensive sensor, they do have a limited range and work best against hard flat surfaces. Small and/or soft objects produce jumpy data. The data consistency can be improved by using a median filter (if you know how to find or write one). I plan to purchase 20 more for my next class.

Never though I'd say this about a mass-manufactured Chinese product with a per-unit price 4% of name brands, but this is a purchase you will not regret. I normally wouldn't even consider buying this due to the "amazon effect": seeing a definitely-too-good-to-be-true deal, then buying it in a moment of weakness and ending up wasting more money in the end because it works like crap and you have to by another one. This is NOT the case with this product!! All units gave results comparable to name brands (like Ping) -- with a minimum distance less than an inch, and good consistency and accuracy. Arrived far before the estimated shipping date -- only took 6 days. My only concern is that two units had slight dents in the "eyes", but it did not seem to affect their performance at all. Even if half of them were duds I would still be impressed by the price and quality of this product. Can't recommend them enough if your doing a robotics project (like me), and need tons of distance sensors without emptying your wallet.

This 10 pack of HC-SR04 ultrasonic distance sensors is a great value. I received them way, way ahead of schedule and tested all 10 the day they arrived. All worked perfectly. It's good to have spares of this really this useful sensor for your microcontroller and robot projects.

All of the sensors did not work properly. I know it isn't a coding issue because I tried the same code with a slightly more expensive sensor and it worked perfectly. Not worth the price paid for what is essentially garbage

Overall:Very decent Cost for performance. I got what I wanted and I was happy with the purchase.Appearance and performance was very similar to an older unit that I received as part of a kit.Pros:The units arrived promptly and adequately packaged.The units seemed new although I did see signs of rework on some of them but 100% of them worked (all 10).All 10 of them performed well over short distances (less than 15 cm) but I saw variations on the longer distance performance.HC-SR04 does not need a driver as the on-board micro-controller does all the heavy lifting. Interface to the Arduino, etc. is by digital pins.Unusual:The units I received were in pairs of sensors (HC-SR04 PCB's and not the transducers) horizontally with the PCB not cut. Very handy if you want to build an array. But otherwise you would need to carefully snap or cut to separate the pairs. Depending on your need it would be a pro or a con. For me it was a Pro.Cons:No documentation such as schematics or datasheet was provided.

It showed up earlier than expected by about 10 days. Tested all 10, all of them worked and I'd say they are all within about +/- 1cm of each other on accuracy, maybe be closer to 0.5 cm, just did a quick test to verify they all worked and checked the distance they were reporting.$13 for 10 vs $30 for one from the local store, can't beat this price!

While they work and they seem to be sufficiently accurate (for my application), the maximum range of these wildly and widely vary from unit to unit.I only tried a few this far (from a batch of 20), but some of them topped out at 2.5m max range while others measured to 3.8m.I wasn't able to measure up till the claimed 4.5m distance.Since I am using these as a backup/addition to motion sensors (presence, leaving room, entering room ) to trigger alarms and lights, this falls into the "good enough" category.For my outside application I am using a sensor that works up till 20m or so, but one unit costs as much as 30 of these.

These sensors only work in very limited situations. If you have a flat target, close to perpendicular, they work great. But, if the target is irregular, or at some angle, these sensors give totally wrong readings. Point into an empty room, with nothing in range, reads about 3 ft. point toward a wall 5 ft away, reads 5 ft. Tried to use them in a robotics project and had to give up.