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https://www.mouser.com/en/c/semicon...gulators/?package / case=TO-92-3&series=LM334
Prices at DigiKey and Newark were outrageous ($5+).
Lets Talk About Constant Current
- Thread starter Wendy
- Start date
Prices at DigiKey and Newark were outrageous ($5+).
Throw us a bone! How much are you willing to spend to get one of them?
The offered one gets you ten genuine parts for just $0.80 more per part than you are paying for something from Amazon. How much is your time and frustration worth you do in having to buy parts, find they don't work, send them back, find something else, that may still not work? Isn't that worth the extra $8.41?
You CAN order just 1 from DigiKey for $0.91 plus shipping and tariff, which brings the total to $9.58. But you can get 10 from them for a total of $16.31. And if you put more stuff that you need or can use on the order, that shipping cost gets diluted very quickly.
Heck, I'll probably be putting in a DigiKey order in the next week or two and I'd be willing to throw this onto it and then put it in an envelope and mail it to you first class.
Buying electronic parts from Amazon is akin to buying them from AliExpress or eBay. They're likely to be counterfeits and you need to plan on testing.
The same goes for modules. I bought 6 hand wave sensors from AliExpress. Fortunately, I decided to test all of them and found that on one the IR LED (or receiver) wasn't even soldered. The modules are flakey because ambient LED or fluorescent lighting interferes with them. AliExpress refunded the full purchase amount, so at least it didn't cost me any money.
That will give you ß at one particular base current and one particular (and unmeasured) value of Vce. You can get Vce through calculation, but really need to take into account the burden resistance of the meter as it is likely to be significant compared to your 100 Ω collector resistor.
I'm not building a curve tracer, just a static test which, if I got it right, will tell me which side is the emitter and which side is the collector.
When you're up to your ass in alligators,It can be difficult to remember that you are there to drain the swamp.
When you're up to your ass in alligators,It can be difficult to remember that you are there to drain the swamp.
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They why are you worried about making a constant current source that can operating bidirectionally???
You have another thread where several people have given you different simple ways to identify which is which.
Oops posting in the wrong thread.
panic mode
- Joined Oct 10, 2011
- 5,333
i have used LM334 (and lately LM334MX in SOIC-8, which is friendlier for PCBA) but ... would not recommend it because of need for external temperature compensation.
LT65-5201 is Jameco part number for LM334Z, so i would think it is more likely that chip(s) got damaged rather than being fake because:
the datasheet link on Jameco website is from Linear, which does not mention ESD. datasheet from TI does. both datasheets state that CC can be down to 1uA.
and even any without mention of ESD it should be obvious that in any product dealing with tiny currents, internal structures are small which makes them inherently sensitive to ESD.
btw. there is a lot of good resources on constant current circuits including Horowitz Art of Electronics and manufacturer notes like
https://www.ti.com/lit/an/snoaa46a/snoaa46a.pdf
https://www.ti.com/lit/an/slyt768/slyt768.pdf
but often this is not as easy as it looks. problems can be traced to different roots (temperature, supply noise, step response/loop instability, parts tolerance, layout, etc.).
results must be verified, no exceptions.
for example voltage references like TL431 can easily oscillate. also basic circuit that uses OpAmp and mosfet that usually like this:
may actually end up as something like one of these:
LT65-5201 is Jameco part number for LM334Z, so i would think it is more likely that chip(s) got damaged rather than being fake because:
the datasheet link on Jameco website is from Linear, which does not mention ESD. datasheet from TI does. both datasheets state that CC can be down to 1uA.
and even any without mention of ESD it should be obvious that in any product dealing with tiny currents, internal structures are small which makes them inherently sensitive to ESD.
btw. there is a lot of good resources on constant current circuits including Horowitz Art of Electronics and manufacturer notes like
https://www.ti.com/lit/an/snoaa46a/snoaa46a.pdf
https://www.ti.com/lit/an/slyt768/slyt768.pdf
but often this is not as easy as it looks. problems can be traced to different roots (temperature, supply noise, step response/loop instability, parts tolerance, layout, etc.).
results must be verified, no exceptions.
for example voltage references like TL431 can easily oscillate. also basic circuit that uses OpAmp and mosfet that usually like this:
may actually end up as something like one of these:
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