Hello, folks. Today I want to tell you about my experience with a L7905CV voltage regulator that I bought online. It turns out that the product that came to me was fake and manufactured in China, and caused me a lot of problems with my electronic circuit.
The L7905CV voltage regulator is a component that is used to get a -5V output from a larger voltage input. It is very useful to power circuits that require a fixed and stable negative voltage. I needed it for an audio project I was doing, and I asked an importer of electronic elements in my country that seemed reliable.
When I got the package, I opened it with enthusiasm and pulled out the voltage regulator. At first it didn’t catch my attention, as it looked like good construction, and even had the logo of the ST company. It had letters and recorded numbers, which read L7905CV and a batch code. I didn’t think it was any strange, so I thought it was a good quality version like any original regulator.
I welded it on my printed circuit board, following the diagram that came on the data sheet. I plugged the power supply and turned on the switch. To my surprise, the circuit began to smoke and unleash a smell of burnt. I turned him off quickly and desolate him carefully. When I checked the rest of the circuit, I realized that several components had been damaged by the excess voltage.
I installed it on a breadboard and fed it with an adjustable power supply. The regulator worked properly up to -13V input, from that value the output voltage began to rise as the input increased, reaching the output even to -9V with less than 20V in the inlet. Reviewing the specification sheet I found that this regulator must support up to -35V entry.
Here’s a picture of the device I bought.
I started researching the internet and discovered I had been the victim of a scam. It turns out that there are many fake voltage regulators manufactured in China, which are sold as if they were original, but do not meet the required specifications or quality. These regulators may have manufacturing defects, low-quality components, or even be poorly connected internally. This means that they do not work properly, and that they can damage the circuits they connect to.
So I recommend that you be very careful when purchasing a voltage regulator online, test it separately first and verify the authenticity and origin of the product before using it in an electronic circuit or device. Don’t be fooled by low prices or tempting offers, because they may end up being more expensive in the end. And if you have any questions, consult an expert or the original manufacturer.
I hope my experience has been useful to you, and that the same thing as me doesn’t happen to you. Until next time.