Diy Strobe for measuring turntable speed accuracy.

by **Steerpike_jhb** » 01 Dec 2009 23:27

Plattenbau wrote:TIf you have another idea till then, just let me know!

I assume you have checked the board for shorted pins by solder blobs.

Is your transistor a BC327, or a substitute ?

by **Steerpike_jhb** » 02 Dec 2009 00:48

Note to JaS:

I have just sent you - by normal e-mail to admin - the .pdf of the diy strobe project WITH THE LED ORIENTATION ERROR fixed.

This error was mentioned in the forum posts some time ago, but for new people who download the PDF and don't read the old posts, it could be a problem.

The error: On the component overlay diagram, the LED outlines were shown with their flat sides (cathodes) facing down towards the cmos chips. The LEDs should be installed with their flat sides facing up towards the transistor.

by **MelodyMaster** » 02 Dec 2009 01:44

Steerpike_jhb wrote:
MelodyMaster wrote:That would be 59.97 Hertz, which is virtually the maximum allowed slowdown during peak power consumption periods in Canada. (The system runs fast overnight to catch up, average frequency over the full day must be exactly 60 Hz to several decimal places.)

D'OH! I forgot they changed the TV frame rate for colour, oops I mean 'color'. 59.94 Hz I believe. Still for PAL and SECAM countries, it is exactly 50.000Hz

I measured quite large instantaneous changes in mains frequency, which would have an impact on synchronous turntables, although would not show up at all in a daily average.
Such ac-mains frequency fluctuations would show up on a strobe disc illuminated by a tv set; even if the tv frequency is "off" by 0.1%, it remains rock-steady.

Sorry, I meant 59.94, I was thinking field rate which is 29.97. I'm a TV tech yet I always make that mistake.. :lol:

But no, a TV can't be used for strobe reference here.

by **Plattenbau** » 03 Dec 2009 21:03

Steerpike_jhb wrote:
Plattenbau wrote:TIf you have another idea till then, just let me know!

I assume you have checked the board for shorted pins by solder blobs.

Is your transistor a BC327, or a substitute ?

yeah - did that... sadfully without a result! for a transistor I used the "original" bc327.

Cheers,

Dennis

by **Steerpike_jhb** » 03 Dec 2009 22:15

Can you put up some close-up photos of the boards?

Since BOTH your examples have the same problem, perhaps there is a fault in the PCB manufacture - a problem with the artwork has allowed a track bridge where there should be none.

by **Plattenbau** » 09 Dec 2009 23:31

Steerpike_jhb wrote:Can you put up some close-up photos of the boards?

Since BOTH your examples have the same problem, perhaps there is a fault in the PCB manufacture - a problem with the artwork has allowed a track bridge where there should be none.

sorry, that it took so long!

here are the shots... hope they are good enough... the last picture is the *.prn file I used...

Any suggestions? I'am helpless...

by **Steerpike_jhb** » 10 Dec 2009 21:57

You're right - those boards did turn out very nicely. And I can see nothing wrong there at all! All perfect.

Any chance you connected the battery the wrong way - I've done that with those PP6 connectors ( read the +/- markings on the battery & forget the connector is actually the opposite)

by **Plattenbau** » 10 Dec 2009 22:57

that would be pretty embarrassing - first thing I'll check tomorrow. Iam not at home right now!

Damn... if thats the reason I go mental...

thx so far & goodnight...

Dennis

by **Steerpike_jhb** » 31 Dec 2009 17:20

Did you have any success with this problem?

I doubt it would show the symptoms you describe, but sometimes when using 'cheap' crystals, I've found they like less loading capacitance to start reliably. Try changing the two small capacitances to 12 or 15pF. Maybe even remove them completely.

by **safe1** » 27 Jul 2010 00:19

Guys,

if anyone still reads this thread:

If i omit the C1 trimmer, should i solder a shorting pin in its place?

by **Steerpike_jhb** » 27 Jul 2010 14:10

Yes, you can omit the trimmer. But don't add a shorting link, just leave the holes open.
Both loading capacitors should then be the same value, around 15pF seems to be a good/reliable value. 33p can be a bit high for some crystals.

by **safe1** » 27 Jul 2010 15:24

Thanks steerpike !

by **safe1** » 29 Jul 2010 09:47

Steerpike,

one last (i hope) question:

What should be connected there? :

by **teac4010** » 29 Jul 2010 18:38

bauzace50 wrote:..... when using 60 Hz current, right?

My gosh, back in the 50's, in Aquadilla, the power frequency was "Right On", when it was on. :lol:

Are you generating your own power?

Regards.