Waiting for your feedback about those transistors.
I've installed small sockets for transistors and tested two kinds already and they sound a bit different. If the 2Sc from Dalbani seems to be legit i will order also some from them to test against the former two types.
Anyway, this preamp sounds very good and i have wima fkp in RIAA not the expensive polystirenes.
I've installed small sockets for transistors and tested two kinds already and they sound a bit different. If the 2Sc from Dalbani seems to be legit i will order also some from them to test against the former two types.
Anyway, this preamp sounds very good and i have wima fkp in RIAA not the expensive polystirenes.
2SC2547E from Dalbani.co.uk - hFE too low..
The 10 pcs 2SC2547E I ordered from Dalbani.co.uk arrived today: They look the business alright, but they all measured much too low for an E version: hFE around 200 (+/-20) 😡
I have tested them with two instruments: cheap multimeter with NPN/PNP transistor tester, and a generic ebay LCR transistor tester. The results varied a bit, but no major differences.
Not sure which voltage and current these two devices use for testing though, but Hitachi calls for 12v and 2mA when testing hFE.
But since the data sheet specifies a minimum hFE of 400 for E type, they must be fake right? - Or should I try to make a proper test setup according to Hitachi specifications?..
The 10 pcs 2SC2547E I ordered from Dalbani.co.uk arrived today: They look the business alright, but they all measured much too low for an E version: hFE around 200 (+/-20) 😡
I have tested them with two instruments: cheap multimeter with NPN/PNP transistor tester, and a generic ebay LCR transistor tester. The results varied a bit, but no major differences.
Not sure which voltage and current these two devices use for testing though, but Hitachi calls for 12v and 2mA when testing hFE.
But since the data sheet specifies a minimum hFE of 400 for E type, they must be fake right? - Or should I try to make a proper test setup according to Hitachi specifications?..
Attachments
More hFE testing...
Have been looking at data sheets for various bipolars, and most specify a pulse voltage between 4 and 6V for hFE measurement, as opposed to the 12V used by Hitachi for the SA2547. I wish I knew the voltage used by my Atmega328 transistor tester or multimeter (not specified anywhere..), but would speculate it is around 5-6v, and 9v max.
I have some A970GR, which has a specified voltage of 6V for hFE measurement, and they all gave plausible results around 400.
Perhaps I should just forget the SA2547 and use another type, but don't want to dump them (or return to seller) without being sure of the hFE data. I don't have any real experience with hFE testing, so am in uncharted territory here.. But the question in my mind is: Does the testing voltage make a significant difference for the measured hFE? In other words, if my SA2547 where tested at 12V, would the hFE read over 400? (and not around 200).
ESP has a lovely looking circuit for the purpose (as he often does!): Project 31 - Full Featured Transistor Tester- but I don't really have the time, or motivation, to build it.
So if someone is able to correctly test a SA2547 for hFE, I would be glad to send a couple in the post. Then we could know for sure if Dalbani is a good source for these or not.
The other possibility I can see, is if anyone has some SA2547 they know 100% to be genuine, and try and measure hFE like I have: On cheap multimeter NPN tester or with Atmega328 transistor tester. But of course that would not be conclusive..
Have been looking at data sheets for various bipolars, and most specify a pulse voltage between 4 and 6V for hFE measurement, as opposed to the 12V used by Hitachi for the SA2547. I wish I knew the voltage used by my Atmega328 transistor tester or multimeter (not specified anywhere..), but would speculate it is around 5-6v, and 9v max.
I have some A970GR, which has a specified voltage of 6V for hFE measurement, and they all gave plausible results around 400.
Perhaps I should just forget the SA2547 and use another type, but don't want to dump them (or return to seller) without being sure of the hFE data. I don't have any real experience with hFE testing, so am in uncharted territory here.. But the question in my mind is: Does the testing voltage make a significant difference for the measured hFE? In other words, if my SA2547 where tested at 12V, would the hFE read over 400? (and not around 200).
ESP has a lovely looking circuit for the purpose (as he often does!): Project 31 - Full Featured Transistor Tester- but I don't really have the time, or motivation, to build it.
So if someone is able to correctly test a SA2547 for hFE, I would be glad to send a couple in the post. Then we could know for sure if Dalbani is a good source for these or not.
The other possibility I can see, is if anyone has some SA2547 they know 100% to be genuine, and try and measure hFE like I have: On cheap multimeter NPN tester or with Atmega328 transistor tester. But of course that would not be conclusive..
That should take only a few seconds to check in the data sheet. Hfe versus Vce or Ic?
For the BC546 the Hfe varies 1:2 from 0.2 to 20mA Ic.
Jan
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Hi Jan, yes good point, and I tried that, but the data sheet only shows hFE vs Ic at 12V Vce. Have not been able to find a plot showing hFE as function of Vce.
Edit: You made an edit just as I posted, so here is an edit to respond to your edit regarding Ic vs. hfe 🙂
According to the data sheet, the SC2547 hFE is not so sensitive to Ic - not 1:2 in any case. That is why I wondered about the voltage.
Edit: You made an edit just as I posted, so here is an edit to respond to your edit regarding Ic vs. hfe 🙂
According to the data sheet, the SC2547 hFE is not so sensitive to Ic - not 1:2 in any case. That is why I wondered about the voltage.
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I have a few 2545E (60V Vceo variant) the head shape and the print on them looks the same like yours only the bottom line reads 4C 4 and their legs are cowboy bent because they are on ammo tape for reel feeding assembly. They measure 510-545 hFE at 5mA Ic says my Atlas tester. When sampled 12pcs. I hope this maybe helps.
Hello Salas, well both yes and no 🙂 Your reading sounds good, but it doesn't tell me if mine are genuine or not. Do you know what Vce value your Atlas uses?
Well it is 800 at 10mA but 'only' 500 at 0.1mA. Maybe check at which Ic your tester works.
Jan
@jvhb
It gives a sequence of pulses that never exceed 4.5V RMS or Vpp 6.24V in a recorded sequence of 7 frames events in the scope's segmented memory storage
Physically your BJTs look like mine
It gives a sequence of pulses that never exceed 4.5V RMS or Vpp 6.24V in a recorded sequence of 7 frames events in the scope's segmented memory storage
Physically your BJTs look like mine
These I just extracted, maybe of some help
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I appreciate the effort Salas - good information there!
Your hFE vs. Vce graph seems to indicate that voltage is not actually the issue with my measurements. But still.. hard to be sure if the devices are good or not.
- If I sent you two of my sa2547, would you measure/test them?.. You would not have to return them.
Your hFE vs. Vce graph seems to indicate that voltage is not actually the issue with my measurements. But still.. hard to be sure if the devices are good or not.
- If I sent you two of my sa2547, would you measure/test them?.. You would not have to return them.
No problem, pm me to send and I will run all available curves options on a sample of those I got vs yours so you will compare
The bunch of SC2547s that I bought from an Amazon vendor, tested very much like yours, Jvhb : 185 - 195 HFE. My bet is they're chinese fakes. I use a cheapo tester but AFAIK it's reasonably accurate. A batch of BC550D gave values of 550-580, as expected.
Maybe 10% of discrepance might be due to error of the testing device, but not 100%. That's too much. Probably your SC2547s come from the same -non Hitachi- factory as mine ..😀
Maybe 10% of discrepance might be due to error of the testing device, but not 100%. That's too much. Probably your SC2547s come from the same -non Hitachi- factory as mine ..😀
Yes I think (fear) you are most likely right.. But I am sending two of them to Salas tomorrow, and we will know for sure.
Good evening all.
I would like to build one preamp for my turntable.
Could you please add me to the list.
Best regards.
Sasha.
I would like to build one preamp for my turntable.
Could you please add me to the list.
Best regards.
Sasha.
