Products > Test Equipment
Seriously, what is the value of a $30 thing that is unreliable?
temperance:
A company where I sometimes work places between 300 and 500 K components / hour. After assembly all components are tested with a flying probe tester. 0.0000001 or even less of all rejects are actually defective components. Alter all this, all assemblies are tested by means of an in circuit tester measuring voltages and currents by means of test points on each PCB trace. Here the same applies. Almost each failure is usually caused by assembly problems and not defective components.
Of course we do have defective components. But defective components failures are usually failures of a different kind. Those components fail after a short period of use. And even then, some of those defects were engineering mistakes like operating components outside their maximum ratings under startup conditions for example.
In my own experience I never received a bad component from a reputable distributor. (On average 400 K components on the shelf for small production runs) If something didn't work it was usually my own error.
-Matching BJT's or MOSFET's: with a bread board and a DMM. (But matched pairs are not that expensive anymore)
-You will need an RLC meter for special cases and for very special cases you probably have to invent your test equipment. (measuring the saturation behavior of inductors for example up 20 A and higher)
-Finding broken semiconductors is easily done with a DMM. If leakage due to aging is a problem I measure some voltages and gently apply some heat to see how things drift around. (I think it is easier than putting every suspect candidate in an dedicated transistor tester.) By doing so you also know if there is anything else wrong in the circuit. (Calculate on the fly which voltages you are supposed to find in there. A rough calculation is good enough to start)
-How to put SMD components into such a test device? DMM or scope probes can probe almost any SMD component or a nearby available solder joint.
I'm just someone failing to see the value of those test devices and prefer poking around in the circuit itself.
shabaz:
There is value for hobbyists. I have a cheap $20 or so LCR meter, I used it when I didn't have anything better, for seeing if my inductors were in the right ballpark, despite knowing that the test is not applying a known frequency signal; that's not the way those low-cost meters work. I still have it, and still occasionally use it, despite having access to better instruments. I sometimes (very often!) do not want a precise measurement, nor might I care that there's no specified accuracy for a $30 instrument. Often with uncertainty, I can live with it, it's part of normal life.
You can learn a lot by observing the change in value as you compress the inductor, or applying different materials close to it. You also can visually observe drift as the instrument warms up, learn your requirements for a better instrument, and notice the need for calibration, or zeroing, and observing the amount of change that occurs when the test wires are moved.
I don't think many engineers would use it to 'select' a component as the OP asked, and there is often no need either, since many circuits can be 'tuned' through voltages or other adjustments. But a $30 meter for observing some quite interesting behaviour for a beginner, and providing results that you may indeed need to verify in other ways (e.g. in-circuit running the end application and seeing if it works) for non-critical work, sounds like a very acceptable thing to do.
thm_w:
--- Quote from: KungFuJosh on August 28, 2024, 06:11:21 pm ---I use the transistor testers to make sure the parts I get from Mouser are functional
--- End quote ---
There is no need to do this though.
KungFuJosh:
--- Quote from: thm_w on August 28, 2024, 10:33:37 pm ---
--- Quote from: KungFuJosh on August 28, 2024, 06:11:21 pm ---I use the transistor testers to make sure the parts I get from Mouser are functional
--- End quote ---
There is no need to do this though.
--- End quote ---
You're joking? I build some complex enough products and I don't want to guess if there's an issue. Every single component gets tested before install. Every single time. And yes, I have found failures that saved me a lot of frustration. Sometimes thanks to a DMM or LCR, and sometimes thanks to these cheap transistor testers.
temperance:
--- Quote ---You're joking? I build some complex enough products and I don't want to guess if there's an issue. Every single component gets tested before install.
--- End quote ---
I find it hard to believe you will be using a $30 transistor tester powered with two AA batteries to verify component performance. Because that's what this topic is about.
I do know that some companies building industrial kW power supplies tested all power transistors before installing them. The same for a company building kW audio amplifiers in de USA. Unfortunately the switching power supplies they developed later on to replace kW transformers were not of the reliable kind and the brand evaporated over night.
Edit:
I do verify what I receive from suppliers after being burned a few time. Getting 27 mOhm resistors instead of 100 mOhm for example. Instant smoke... But I don't test all components. That would be about 90 K components this month.
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