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Doug Self Preamp from Linear Audio #5
Doug Self Preamp from Linear Audio #5
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Old 24th August 2021, 07:58 PM   #1811
asuslover is offline asuslover  United States
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BC546 will work great here .
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Old 24th August 2021, 08:02 PM   #1812
fvzeppelin is offline fvzeppelin  Germany
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Quote:
Originally Posted by smartx21 View Post
BC550C is low noise NPN, hFE~500.
BC560 is PNP.
BC337 is NPN, 800 mA, general purpose.
In place of BC550C, try 2SC1845 or 2SC2240. For the PNP. their complementary pair.
To drive a relay with higher gain, I use BC517 (NPN, darlington).
2SC2240 should work.
2SC1845 is limited by maximum collector current of 50mA and hFE (s. Fig.3 in https://cdn-reichelt.de/documents/da...SC1845-FSC.pdf).
Both have different pinouts.
Noise doesn't matter for the relay drivers.
I would recommend a Darlington, too. Or use the two BC550 as a Darlington
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Old 24th August 2021, 08:13 PM   #1813
fvzeppelin is offline fvzeppelin  Germany
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Quote:
Originally Posted by asuslover View Post
BC546 will work great here .
Again, hFE... I'd recommend the B or C types.
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Old 24th August 2021, 08:35 PM   #1814
fvzeppelin is offline fvzeppelin  Germany
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Quote:
Originally Posted by fvzeppelin View Post
Hm, when using XLR inputs, 4 relays need to be driven simulaneously, i.e. 4*12mA=48mA. Current through the 1st BC550 is limited by the 47k resistor, i.e. 14V/47k=0.3mA. This means that the 2nd BC550 needs an hFE of at least 160@50mA. Looking at Fig.3 in the datasheet of the BC337-40, it *should* work, but it's close...
https://www.onsemi.com/pdf/datasheet/bc337-d.pdf
Correction: It's 11V, not 14V, so the required hFE is ~200.
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Old 25th August 2021, 02:47 AM   #1815
kouiky is offline kouiky
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Quote:
Originally Posted by glenv6 View Post
I bought the BC550 and BC560 from Tayda Electronics.
I was just checking them out. Any appreciable difference between the “CTA” end suffix and the “B” versions?
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Old 25th August 2021, 05:17 AM   #1816
metallicus69 is offline metallicus69  Netherlands
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I used BC546C successfully in those positions, as I have a ton in my box
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Old 25th August 2021, 09:58 PM   #1817
glenv6 is offline glenv6  United States
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Quote:
Originally Posted by kouiky View Post
I was just checking them out. Any appreciable difference between the “CTA” end suffix and the “B” versions?
I believe the CTA is the SOT package, whereas the B is a TO-92. This build uses the TO-92 package.
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Old 6th September 2021, 03:45 PM   #1818
glenv6 is offline glenv6  United States
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Default Rear Panel FPD or DWG Files?

Hello Builders,
Does anyone have Rear Panel FPD or DWG Files? I have Carl’s fpd files for the front panel (1U/2U), but I haven’t found these files for the rear and would like to avoid having to draw them myself if possible.

Thanks in advance!
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Old 6th September 2021, 11:28 PM   #1819
Carl_Huff is offline Carl_Huff  United States
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Default Rear Panel FPD file

glenv6,

Here is a rear panel layout for a 1U case. I cannot remember who sent it to me, so thank you whoever you are.

Dropbox - REAR_PANEL_1U.fpd - Simplify your life
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Old 7th September 2021, 01:20 AM   #1820
still4given is offline still4given  United States
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Doug Self Preamp from Linear Audio #5
Here is the one I drew.

https://www.diyaudio.com/forums/atta...rear-panel-pdf
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