Having used 3055 type bipolar transistors for years with all manner of prefixes and suffixes in either TO3 or TO220 packages, I opened up something to repair today to find a MTP3055E inside and behaving strangely.
Turns out it is an N channel Mosfet! GRRR!
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Of all the numbers they could have given it why choose 3055 that so widely known for being a bipolar power transistor.
I guess it's difficult if you just refer to 4 digits to describe such a thing. I have mine labled as 2N3055 .
3055 is also the code for an alpha wire. I wouldn't allow my studetns to just type 3055, I'd expect them to be able to type the name in and order code and supplier, that's what teaching is about. ;-)
Other confisions are when the BC182L and BC182K are the sma e spec but differnt pinout.
We tend to use the 2N2222A more now and I'm trying to replace them with the cheaper versions PN2222 as for what the students use them for they should be OK.
Almost certainly - in fact, when they were released in the UK by Mullard they had no suffxes and I don't ever recall seeing a Mullard branded one that did although the parent company, Philips, shows them clearly on its datasheet:
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109_4.pdf
I suspect this make 'em 'n' measure 'em procedure is much older than semiconductors.
20% carbon composition resistors, for example, when there were only 6 values in each decade and there was no guarantee of every one containing the same amount of carbon in the mixture they were made from.
The first varicap diodes designed for use in UHF and VHF tuners had such wide variations that Mullard sold them in individually matched sets because of the need for all the tuned circuits in a tuner unit to track accurately.
I assume it was easier/cheaper for the tuner manufacturers to buy them in bulk and test/sort them for themselves, though.
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