Fake BB910 varactor diodes???

[eccerr0r]

After a bit of internal debate I think these *are* capacitors despite also being diodes, so I post this here...

I have a need for a varactor for a project. I was wondering about BB910s varactors. Apparently Philips has a datasheet with a DO-34 or axial version of this device, and I think Philips should be a reputable maker of semiconductors.

However I'm seeing TO-92 crop-pin versions of this device from china marts. Anyone know if these are work-alikes or are they complete phonys and wouldn't even work like a varactor?

[Agent24]

Re: Fake BB910 varactor diodes???

If you can get the genuine Philips ones from a proper supplier, then do that. You'll have much less of a headache that way.

Forget generic Chinese parts except as a last resort. If they are actually varactors, they probably won't behave exactly the same as the genuine ones, and I doubt the Chinese are going to give you a datasheet which has the real specifications, if they are different. Even second-sourced parts from reputable manufacturers don't behave the same.

If you use the generic ones and your project\repair\whatever doesn't work, you'll never know if the parts were fake or just the wrong number or if you did something wrong or what.

Using genuine parts at least gives you a high degree of assurance (but not 100%!) that they will work as the datasheet says they will, and if they don't, then you know it was probably your mistake or something else in the circuit is faulty.

Is the money you'll save on the generic parts worth your time and potential hassle for an unknown quantity?

[eccerr0r]

Re: Fake BB910 varactor diodes???

Well this is for fun, and I really want to pay as little as possible for these things. It's not a repair job, and there's no real time schedule for them. I'm actually speccing possible parts for my project - just collecting possible parts that may or may not fit my needs based on their data sheets.

But what I don't know is perhaps there is another manufacturer that does make equivalent working parts, really I don't care if it's DO-34 or TO-92; probably easier for TO-92 because I don't have to lead form when assembling it.

Incidentally, Mouser has only ONE through hole varactor? Hmm... Working with through hole at the moment, so this will be a problem...

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I just found someone with a DIY kit that uses the TO-92 BB910 and does work like a varactor, else the kit wouldn't work... Might have to try it, mostly because I probably need to get two or more and hook up in parallel to get the capacitance I need.

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Oh jackpot! sort of...! I found an old dollar store "china" FM radio and found a varactor marked "B910" ... and since the radio at least worked at one point (haven't tried it yet...) the varactor should be working. So it seems that this part is somewhat rampant in duplication.

Not sure if I can actually use the VCO in the TDA7088 directly yet however...would save me from making that circuit I need to replicate (but at a different frequency range...) If I short out the antenna input, the mixing DC with the VCO output would be... the VCO output, saving me from designing a VCO?

[Agent24]

Re: Fake BB910 varactor diodes???

Well, if you aren't fussed about the potential issues, the generic BB910s are probably OK. It just may make troubleshooting that bit harder.

I don't know much about radio, but I doubt that shorting the antenna will achieve what you want. I'd guess you would need a completely different IC.

[eccerr0r]

Re: Fake BB910 varactor diodes???

I probably need to get another one, the design I'm doing feasibility on is much slower than FM radio and probably needs more capacitance.

I just thought of a better plan instead of mixing with a DC signal: mixing it with itself (if this is possible...) This should work plus increase amplitude! Except the fact there may be a phase shift, then that could be a problem, though possibly not insurmountable.

[stj]

Re: Fake BB910 varactor diodes???

probably the factory had a to92 molding machine but not a do34 one.

[eccerr0r]

Re: Fake BB910 varactor diodes???

I think the TO-92 BB910s are not made by Philips, though no idea who. Definitely a clone of some sort, unfortunate that they used the same marking as Philips (annoying, these part number aren't controlled by JEDEC?).

The DO34 case is probably more expensive, too, at least the Philips one is glass sealed I think when looking at the picture.