For some time, I’ve been designing a small group of alarms for cars, motorbikes, and (very) small houses. I’m looking at using some of the low cost sensors sold for Arduino’s and Pi’s. The specific devices I’m interested in are:

PIR Sensor Module
ADXL335 Triple Axis Accelerometer Module
HC-SR04 Sensor Ultrasonic Sensor Module
RCWL-0516 Microwave Radar Sensor Module

I’ve made a few prototypes which are working well, but....

Does anyone on the group have experience of their long term reliability over several years?

Cheers
MalcolmZA
(In South Africa)

 

A rule (not the only one) is that if it goes into a product you need a commitment from a manufacturer you can trust, and that means actually finding out how the modules are made and how their parts are sourced.

 

A rule (not the only one) is that if it goes into a product you need a commitment from a manufacturer you can trust, and that means actually finding out the modules are made and how their parts are sourced.

Hi Dick,
I hear you , commitment is a very rare commodity in SA.
The only supplier in SA which I'd trust to supply parts from vetted manufacturers Is RS Components.
The premium you pay for that luxury often makes a project uneconomical.

Many of the low cost Asian sensors are available from multiple of local suppliers so there is security in supply there.

I'm doing some work with the RCWL-0516 Microwave Radar Sensor at the moment with the aim of reducing its sensitivity and making it more directional. When I achieve that goal I'll temperature stress a few of cheaper versions and see if they fail quickly.

Cheers
Malcolm

 

Many of the low cost Asian sensors are available from multiple of local suppliers so there is security in supply there.

"Low cost" and "Asian" together would concern me. I'm certain you can buy quality parts manufactured in Asia at a reasonable price. I'm equally certain you can buy counterfeit parts with the logos of respected manufacturers in Asia for a low price too.

If you're going to buy parts manufactured in, or distributed from, Asia, do some homework and make sure that you're buying from an authorized reseller; otherwise, I'd assume it's counterfeit.

In the US, the military was buying parts from a business (guy) in Southern California who was having substandard parts relabeled.

This is an excerpt from a warning from Robin Gray, Chief Counsel for the ECIA (Electronics Components Industry Association):

 

I have no proof other than buying and using chinese modules. They are cheap. They work. Would I use them in a Commerical product? NO! They have no provenance! What parts were used? Parts manufactured by? Part Product Data File? These things are so cheap that I suspect the parts used are probably off-spec scrap. I know that when I buy kits from china, the first thing I do is test the parts. Capacitors, in particular, have been 100% (or more) off-spec even allowing for a generous 20-50% quality factor. These modules, like many chinese products, are produced en-mass in a single factory and labeled whatever the vendor wishes stenciled onto them. I strongly suspect they are produced at a loss (or very low markup) just to keep their factories operational. There has been so much misinformation/propaganda coming out of china and goods that fail international standards (that they are marked as) that I treat anything produced there with a high degree of skepticism and mistrust. Yes, they produce some very high-quality electronics but they also produce a whole lot of trashy ones too. That and the fact that many of these modules are knockoffs/stolen intellectual property of legitimate foreign companies. I know that I am being hypocritical because by buying this crap from china I am contributing to their malfeasance.

 

One thing is that the low cost of Asian supply has enabled a larger body of minds to explore and create. Let your customer determine product quality, then don’t let them down.

 

Many thanks for the opinions.
I've bought a few RCWL-0516 motion detection sensors, after a bit of fiddling I've got them de-tuned sufficiently to work in a car.
Next step is to install a few locally and monitor if there are problems before making a bigger batch.

Cheers
Malcolm