It's 2016. I accidentally got a bag of 2SA1541 "D" grade from an old small surplus shop in Thailand. After searched on this forum, seems 2SA1541 is rarely mentioned nor having its photo here.
Any advice if they are genuine? How can we make (simple) tests on them? Thanks in advance.
Any advice if they are genuine? How can we make (simple) tests on them? Thanks in advance.
Attachments
Nice find! These look like Sanyo video drivers - and great low Cob value. Good high voltage rating and decent current. Will probably work well and similar to KSA1381/KSC3503.
http://pe2bz.philpem.me.uk/pdf on typenumber/0-9/2SC3956.pdf
Were they cheap? I have found great success buying bags of 20 to 40 of these types of transistors from Aliexpress (typically $5 to $8 a bag).
@xrk971
Thanks. Quick look on the datasheet, their Ft is impressive. This one kisses 150MHz at 5ma ( A1381 required 10ma). The down side is Hfe i.e. only ~60-70 but consistent among them.
I got them a while ago. I think it was US$40 for 200 pcs taking risks they might be fake. I might create a simple amp to see if they are genuine.
Thanks. Quick look on the datasheet, their Ft is impressive. This one kisses 150MHz at 5ma ( A1381 required 10ma). The down side is Hfe i.e. only ~60-70 but consistent among them.
I got them a while ago. I think it was US$40 for 200 pcs taking risks they might be fake. I might create a simple amp to see if they are genuine.
The low hFE would not be as great a problem when they are used to cascode another low power high hFE fast fT transistor.
They could also be used as the second transistor in the dual transistor VAS as shown in Blameless by D.Self.
aAnd as the pre-driver in a triple EF output stage.
They could also be used as the second transistor in the dual transistor VAS as shown in Blameless by D.Self.
aAnd as the pre-driver in a triple EF output stage.
What about more recent parts in SMD packages?
2SA1418/2SC3648 (Onsemi) SOT89
DXT5401/DXT5551 (Diodes) SOT89
DZT5401/DZT5551 (Diodes) SOT223
Not completely unusable by hobbyists
2SA1418/2SC3648 (Onsemi) SOT89
DXT5401/DXT5551 (Diodes) SOT89
DZT5401/DZT5551 (Diodes) SOT223
Not completely unusable by hobbyists
5551/5401 don't make ideal VAS nor pre-driver transistors.
I would expect the smd versions to be similarly unsuitable.
Post the a1418/c3648 datasheet/s so that we can make a more informed opinion.
I would expect the smd versions to be similarly unsuitable.
Post the a1418/c3648 datasheet/s so that we can make a more informed opinion.
http://www.onsemi.com/pub_link/Collateral/EN1788JP-D.PDF
Dissipation 500mW without heatsink
Pretty linear,
Relatively low Cob < 7pf ~ 50V
IMHO, speed are questionable: 50MHz @5ma, 70MHz @10ma, 100Mhz @ 20ma. The 2SC is even a bit slower.
AndrewT, in what way are the 5401/5551 unsuitable for the task, other than power dissipation of a TO-92 ?
SOT 223 package is easily capable of 1W dissipation and this meets a lot of VAS requirements. If the Cob of DZT5401/5551 is not low enough for your ultra low distortion SOTA laboratory project, then have a look at more SOT223 package types such as BF720-723 series. These are actually specified like the old Philips BF467-470 favourites in TO202 and TO126 packages. NXP, Infineon and On-semi are manufacturers so there shouldn't be too many supply problems.
http://www.mouser.com/ds/2/302/BF720_722-840010.pdf
http://www.mouser.com/ds/2/302/BF723-840309.pdf
From experience, Diodes Inc. BJT datasheets are often brutally honest in specifying their worst case numbers, like 6 pF Cob when the typical figure quoted by other manufacturers for similar product might be 3pF. It's misleading to compare parts by the only figures that appear when there is often little practical difference to get excited about. Too bad you already spent the money though 😱
http://www.mouser.com/ds/2/302/BF720_722-840010.pdf
http://www.mouser.com/ds/2/302/BF723-840309.pdf
From experience, Diodes Inc. BJT datasheets are often brutally honest in specifying their worst case numbers, like 6 pF Cob when the typical figure quoted by other manufacturers for similar product might be 3pF. It's misleading to compare parts by the only figures that appear when there is often little practical difference to get excited about. Too bad you already spent the money though 😱
Last edited:
The power handling of sub-minature SMD devices can be varied considerably by adjusting the amount of PCB copper attached to its collector. A degree of experimentation is required though - but the data-sheets are relatively conservative on the signal sized devices.
I would not use it for either VAS or pre-driver duty.
fT @ 3mA to 5mA is low.
Cob @ 10V is high.
The 100ms SOA @ 50Vce is superb for a small device.
You can catch some KTC3423/KTA1360 on the Ebay of Aliexpress, if You are lucky...
Sajti
