BCY87 Question

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Alfrede
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BCY87 Question

Post by Alfrede » Wed Mar 25, 2020 12:35 pm

Hi Dudes,

i have a question can i use this Dual NPN Transistor for making a module?

BCY87 Datasheet

I found at googeling that a person from russia should take it for an replacement for an LM394.

So have you any ideas what i can do with this Part?

Thanks

Alfrede

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EATyourGUITAR
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Re: BCY87 Question

Post by EATyourGUITAR » Wed Mar 25, 2020 3:42 pm

broken link. try this
http://pdf.datasheetcatalog.com/datashe ... /BCY89.pdf
The BCY87 and BCY88 are intended for use in pre-stages of differential amplifiers where low offset, lowdrift and low noise are of prime importance
I am not an expert in exponential converters but it looks like +/-%10 HFE from T1 to T2. I think we can trim that out on the 1v/oct calibration. the deltaV/deltaT is excellent. the deltaI/deltaT is also excellent. max uV/K = 3 and max uI/K = 0.5
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Alfrede
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Re: BCY87 Question

Post by Alfrede » Fri Mar 27, 2020 1:36 am

Okay thank you for your first look. What would you do with it when you have them?

jorg
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Re: BCY87 Question

Post by jorg » Fri Mar 27, 2020 9:22 am

You could also use BCM847; it's cheap, plentiful, and works nicely for expo converters, ladder filters, diff amps, etc.
https://assets.nexperia.com/documents/d ... _BS_DS.pdf

BCM847 is SMT; don't know whether that's a problem for you. BCM847BV grade has Vbe matching to 2mV, compared to 3mV for BCY87 (or 6mV for BCY88). hfe matching is the same for BCM847 and BCY87; BCY88 is slightly worse.

BCM847 is much faster (100MHz vs 10MHz). BCM847 is lower noise (NF=2.8dB vs 4dB). Voltage and power limits are about the same; though BCM847 handles slightly higher power. DC gain is more tightly controlled toward the high end (200-450 for BCM847 vs 100-450 for BCY87).

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EATyourGUITAR
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Re: BCY87 Question

Post by EATyourGUITAR » Fri Mar 27, 2020 10:10 am

Alfrede wrote:
Fri Mar 27, 2020 1:36 am
Okay thank you for your first look. What would you do with it when you have them?
I think it is obvious that it will be a VCO but it could also be a VCF with 1v/oct pitch tracking exactly the same exponential converter as the VCO.
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