BC547 question ( applied to other ICs)

[Thalassa]

Hello Yves

I have little experience on DIY and this will be the first time that I order my own components so I have some doubts.

I'm ordering the necessary components to build some of your modules and I have a question about the BC547

One of the modules that I want to build is the Matched BC547 VCO version. On this module the BC547 has to be BC547B, and the question is that in other modules I need also BC547 ( Moog Filter, Clock Divider,diode ladder filter,lfo ). So I'm wondering if I can order a bunch of this BC547B to use on the other modules and this way will be easy to find 2 matched BC547 ( I also need to match them for the minimoog filter). I can't find the differences between the models because the datasheet that I found are the same for both models.

My doubt can be applied for other IC, when you don't specify other thing,can I use whatever version I have ? For example when you said TL074, Can I use one of this TL074CN ,TL074BCN ,TL074ICN?

Thanks :

Pablo

[wmonk]

Hi Pablo,

There are typical two common types of BC547: the BC547B and the BC547C. The difference is the pin-layout.
You can see the difference here: http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXytvtz.pdf

Perhaps it's a good idea to have the schematics at hand when building. But I think Yves only uses the B.

Cheers,
Wmonk

EDIT: sorry, did have something wrong. The Yusynth ADSR needs BC547C,

[yusynth]

In general I use BC547C in my designs because they can handle most of the currents that are required in those circuits. For the VCO I used the B kind because they offer a Ic versus Vbe relationship that is better suited for an exponential current converter.

Anyway a BC547b is really cheap, therefore you can buy a bunch of them in order to select matched pairs. In general when coming from the same production batch you can find four matching pairs out of 25 trannies. And even in circuits where I use BC547C you may use BC547B.

Concerning the TL074 you may use any kind, it really doesn't matter.

[Thalassa]

Thanks for your help

[Sebo]

[wmonk]

Yeah, I was wrong. Realised it when I had it posted, but the beer was waiting on me
Anyway, it's always good to have a pile of both B and C to get good matched pairs, and they're cheap to!

[Thalassa]

[intoodeep]

A little confused.. people who have successfully built the moog filter clone, what trans did you use for the ladder? BC547, BC547B, or BC547C?

[Sebo]

I don't think that the subfix letter matters. They should be the same letter
because it will be easier to match them.

[stilz]

The subfix letter matters! But Yves describes it very good. Use BC547C

[intoodeep]

Thanks for the reply, i got the filters working using 547C. The subfix is the range that the current gain will be in i think and it definitely does matter afaik in the circuit.. I also had a lot of problems using 547 and 547B in the expoconverter for the VCO. That one I had to use B.

[stilz]

Nice to hear it works now.

[MrZ]

I used 2N3904 for the tran ladder of the moog vcf clone
it works.

[Freq Band]

What about BC549 (b) ??

I mistakenly bought these, but I see they are "low noise".
Will these work ?
(minimoog transistor ladder VCF)

BC549 voltage specs:
CBO 30v
CEO 30v
EBO 5v

BC547 specs (suggested part)
CBO 50v
CEO 45v
EBO 6v

[yusynth]

I see no reason why they would not

[Freq Band]

I'll give it a try.
Thanks YuSynth !!