Rotel RCD-02 Kwak-Clock upgrade

[baggystevo82]

Hello everyone!!
I'm just about to build Elso's mk7 clock, and noticed that the BC550C on the schematic is a low noise version of the BC550. Would it also be better for the 'opposite' transistor BC560 to be a BC560C low noise one too? I source most of my components from Maplins and Farnell, and the only place I could get the low noise BC560C was RS, which would mean £5 postage for a few transistors.

http://uk.farnell.com/jsp/catalog/vi...prodId=3163246

On this page is listed a BC557C, which appears to have similar spec to the BC550C, apart from being PNP and not NPN. Would this make a better choice than a normal non-low-noise BC560 do you think? I've had a look round on the forums, but everyone I assume just sticks with the normal BC560. I have both the BC557C and the BC560 sat on my desk, so it is now only a matter of choosing which one would be best.

As I was posting this thread, I thought I may as well include a picture of the clock currently installed in the CDP, any suggestions as to which resistors to remove and exactly how to hookup the Kwak-Clock?

One more thing, would it be best to use a double sided PCB with one side left unetched to act as a ground plane, and only bring the ground through to the other side where required? Or would it be better to cram all the required ground tracks onto the bottom with the rest, working as a single sided board? Also, if I use a ground plane, is it best to space the components away from the board a bit to reduce potential interfierance from the components being so close to the ground plane?

Does anyone have any general experience upgrading these CDP as they seem a bit rare on the forums, people normally seem to go for the more expensive 10** series of Rotel stuff.

Thanks in advance for any help!!
Steve

[baggystevo82]

Well, noone seemed to reply so I went ahead with the BC557C, hopefully it will work OK. The circuits all finished now (with the exception of removing the crystal from the CDP) and ready for testing and setup on monday.

Please comment on any improvements/modifications to this as I doubt somehow this will be the final version...

Thanks Elso for sharing this!!! In case you were wondering where I got the schematic you emailed my housemate (he's on this forum as 'Hesky'). I know you like to keep these things a little more personal than just posting up the schematic on here, from what I've gathered anyway.

The output is the hole on the end of the resistor on the far left. The power supply inputs are hidden in this pic

[baggystevo82]

And this is the rear view, with the power supply coming in behind the main caps.

[Elso Kwak]

Hi Steve,
On www.farnell.com the BC550C from Philips is listed as part# 3163246.
I designed a single sided PCB as double sided are a pain to repair and also more difficult to make.
I am using much smaller ferrite beads, 3 x 3 mm with only a half turn of wire.
Good luck with your clock project!

[baggystevo82]

Hi Elso,

I'm using the BC550C you mention already (same source too), it was the BC560 I was concerned with. Ill try and explain myself better. Have you used the BC560 and not the BC560C low noise version for availability reasons? I'm guessing there's some advantage to using the BC550C over the BC550? So I assumed that it would be best to use a low noise transistor on the opposite side too. Looking through the data sheets at Maplins the BC557C looks exactly the same as the BC550C apart from being PNP, so I went for that. Was this a good thing to do?

As for using the ground plane it hasn't been too much hassle. I've just used components legs to join the ground plane through the PCB onto little mini-tracks that then join the components in the required places. I enjoyed myself anyway . It also meant I could cram all the components in nicely and still have reasonable and manufacturable track widths, as no ground tracks are required underneigh, and in my single sided design these accounted for around half the tracks. Unfortunately size is a fairly important consideration in my CDP, there's not too much room there. Ill make my own one day.......

Ill bear the ferrite beads in mind when i try and set it up on monday. Any ideas or clues as to how these may influence the output signal?

Thanks for the suggestions,
Steve

[Elso Kwak]

Hi Steve,
BC560C is part# 992847 from www.farnell.com , Onsemi part. The parts mentioned by you will also work but were not specified by me.

[baggystevo82]

Hi,

Sorry I meant the data sheets at Farnell, not Maplins....bit confusing...

Anyway, just took this picture of the underside to show how simple the tracks are for this layout. If you could let me know what you think Elso about how it might perform compared to yours I'd be very grateful.

Thanks again,
Steve

[baggystevo82]

Hi,

I can't keep up with this pace of replying!! I had a look at the UK Farnell site, and they don't have BC560C. I searched for 992847 as well, but no result. Perhaps Farnell only stock these in your country? I noticed the websites for the different regions were very different, so I guess that may be a sign that they operate fairly independantly. Ahh well, so long as it still works

Thanks,
Steve

[baggystevo82]

Hello,

I just looked on the Swiss Farnell site and they do have BC560C. Bit strange why they have it and the UK Farnell people don't.

[Elso Kwak]

Originally posted by baggystevo82
Hi,

Sorry I meant the data sheets at Farnell, not Maplins....bit confusing...

Anyway, just took this picture of the underside to show how simple the tracks are for this layout. If you could let me know what you think Elso about how it might perform compared to yours I'd be very grateful.

Thanks again,
Steve

Hi,
Compared with my PCB you have very long tracks. But I presume yours will function as well. I don't have a groundplane at the componentside but groundfil between the tracks. I hope you will understand why I don't show a picture of the solderside.
Attached a picture courtesy of Cobra2.