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!
Of all the numbers they could have given it why choose 3055 that so
widely known for being a bipolar power transistor.
Moral: Don't assume anything!
On Monday, 15 January 2018 12:46:24 UTC, Fredxx wrote:
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. ;-)
On 15/01/18 13:14, email@example.com wrote:
a transistor spec is a minimum spec.
Not a maximum, not a typical.
so its perfecly possible that significantly better transistors can share
the same part number.
e.g. back in te day most BC107 would handlee 70V. but the spec only said
"When one man dies it's a tragedy. When thousands die it's statistics."
In the case of the BC107 range, the A, B and C versions were
graded according to their DC current gain into three bands.
A BC107 without a suffix could have gain figure anywhere in
the range of 110 to 450.
The BC108 had an even greater gain spread - from 110 - 800
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:
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.
On Tuesday, 16 January 2018 11:10:46 UTC, Terry Casey wrote:
and there't the BC109a,b,c
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.
On Monday, 15 January 2018 22:33:26 UTC, The Natural Philosopher wrote:
Must be a while since you read any transistor data sheets
they can, but that isn't the issue. Here's what wiki says:
"With changes to semiconductor manufacturing technology, the original proce
ss became economically uncompetitive in the mid-1970s, and a similar device
was created using epitaxial base technology. The maximum voltage and cu
rrent ratings of this device are the same as the original, but it is not as
immune from secondary breakdown; the power handling (safe operating area)
is limited at high voltage to a lower current than the original."
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