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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 20th Jan 2022, 1:47 pm   #1
symon50
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Default BC650 equivalent

Hi, I'm trying to track down a couple of BC650 transistors to build a small dipole preamp front a R. A. Penfold aerial projects book. Having recently retired I thought this would be a good start to get back into electronics, particularly radios. Can anybody recommend a good transistor equivalent book or 2. Google search doesn't throw up any supplies of the transistor apart from Cricklewood electronics but seems they have no stock. thanks
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Old 20th Jan 2022, 2:53 pm   #2
G6Tanuki
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Default Re: BC650 equivalent

Historically, the default transistor-equivalents book was T.I.T.S. - Towers Internaltional Transistor Selector. Copies [there were several volumes] occur occasionally on the usual auction-sites.

BC650 is a fairly mundane transistor...

BC650=Vcb=30v vce=30v veb=6v Ic max=100ma P.TOT=625mw Ft Min=100m Hfe =400min


Something like a MPSA18 would work. Mouser-UK have them for 73p each,
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Old 20th Jan 2022, 8:56 pm   #3
symon50
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Default Re: BC650 equivalent

Thanks very much for the reply, appreciate it.
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Old 21st Jan 2022, 2:20 am   #4
Uncle Bulgaria
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Default Re: BC650 equivalent

I got a copy of TITS from the forum. If you ask in the 'wanted' section, someone might have one they can send you.

It's been useful to check whether transistors I have in my box are what I need, even if the circuit asks for something else! It seems lots and lots of these are basically interchangeable unless a very specific parameter is what the circuit's designed for.

Another resource I've used, especially for MOSFETs which my TITS doesn't cover, is https://alltransistors.com/

Search for the transistor number, choose the variant and at the bottom of the listed specifications you'll see "xyz transistor equivalent substitute". Clicking that will give you a long list of transistors that are close in various ways. More comprehensive but can be less convenient than a book. I find the TITS index of base types and pinouts to be invaluable as well.
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Old 21st Jan 2022, 2:35 am   #5
symon50
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Default Re: BC650 equivalent

Thanks
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Old 21st Jan 2022, 5:57 pm   #6
Philips210
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Default Re: BC650 equivalent

Hi.

In my Jaeger Elektronik databook it lists the commonly available BC550 as a suitable replacement for the BC650.

Regards,
Symon
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Old 21st Jan 2022, 11:59 pm   #7
Steve_Bell
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Default Re: BC650 equivalent

My version of TITS (Update 4, from 1990) lists the BC650 but does not suggest any equivalents.
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Old 22nd Jan 2022, 9:12 am   #8
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Default Re: BC650 equivalent

Here's a substantial list of equivalents - https://alltransistors.com/crsearch....=400&caps=TO92

Andy.
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Old 28th Jan 2022, 12:27 pm   #9
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Default Re: BC650 equivalent

It seems the 'alltransistors' site recommends a darlington substitute
I suppose it might work!!

I would guess, for an antenna preamp, the best option is something with high gain at HF and low noise, and it probably (?) doesn't need to dissipate a lot of power so maybe a 100mW device is enough - since a physically smaller device is likely to push the HF gain up.

dc
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Old 28th Jan 2022, 2:45 pm   #10
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Default Re: BC650 equivalent

It seems to be a pretty bog standard transistor. I imagine the original designer used it simply because he had some to hand.

I would expect the usual BC548/2N3904 to work just as well.
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