milosz
500+ Head-Fier
- Joined
- Aug 17, 2009
- Posts
- 971
- Likes
- 123
This is something that can REALLY grab us DIY'ers!
A counterfeit device is likely to fail, and sometimes will take with it a lot of other parts, costing money and maybe even starting a fire!
If you take a 15 cent transistor, or maybe a rejected part from a scrap bin, and re-label it to match a $15 part- there's PROFIT to be made. And where there's a way to make a quick buck, there's someone out there doing it.
Here's some good info re: counterfeit transistors
http://sound.westhost.com/counterfeit.htm
There are basically two ways to tell if a transistor is "right' or not.
The first is to run a set of it's characteristic curves. You can do this with variable power supplies, meters and patience. Or, you can get a TRANSISTOR CURVE TRACER. Alas, these are not cheap.
However, running the curves and comparing them to the manufacturer's published specs is the best way to be absolutely sure. Also, if you have to match devices for some project, it's handy to be able to run curves. Obviously, this is a moderately expensive proposition, and only very active - or wealthy- DIY'ers will likely go down this route. Maybe a local audio club could buy a curve tracer for use by members- it's an idea, anyway.
Short of actually running a full set of curves, there's inexpensive ways to measure a few characteristics that are often telltales of fake parts. BREAKDOWN VOLTAGE is one that is good to check, 'cause if the part under test has a lower breakdown voltage than the design calls for, you're screwed. The Chinese made Duoyi DY294 Transistor Tester offers a decent breakdown voltage test, as well as the ability to check other parameters. And it's not expensive- I've seen it for under $50 US including shipping. Look on eBay or other online sources for this handy gizmo.
A counterfeit device is likely to fail, and sometimes will take with it a lot of other parts, costing money and maybe even starting a fire!
If you take a 15 cent transistor, or maybe a rejected part from a scrap bin, and re-label it to match a $15 part- there's PROFIT to be made. And where there's a way to make a quick buck, there's someone out there doing it.
Here's some good info re: counterfeit transistors
http://sound.westhost.com/counterfeit.htm
There are basically two ways to tell if a transistor is "right' or not.
The first is to run a set of it's characteristic curves. You can do this with variable power supplies, meters and patience. Or, you can get a TRANSISTOR CURVE TRACER. Alas, these are not cheap.
However, running the curves and comparing them to the manufacturer's published specs is the best way to be absolutely sure. Also, if you have to match devices for some project, it's handy to be able to run curves. Obviously, this is a moderately expensive proposition, and only very active - or wealthy- DIY'ers will likely go down this route. Maybe a local audio club could buy a curve tracer for use by members- it's an idea, anyway.
Short of actually running a full set of curves, there's inexpensive ways to measure a few characteristics that are often telltales of fake parts. BREAKDOWN VOLTAGE is one that is good to check, 'cause if the part under test has a lower breakdown voltage than the design calls for, you're screwed. The Chinese made Duoyi DY294 Transistor Tester offers a decent breakdown voltage test, as well as the ability to check other parameters. And it's not expensive- I've seen it for under $50 US including shipping. Look on eBay or other online sources for this handy gizmo.
