Diy Strobe for measuring turntable speed accuracy.

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.

by **Steerpike_jhb** » 29 Jul 2010 19:45

safe1 wrote:one last (i hope) question:
what should be connected there? :

Nothing, or just solder pins (cut off component leads). Those two pads are test points for a frequency counter or oscilloscope.

by **irwan_su** » 30 Jul 2010 01:10

Since I don't understand how to read the scheme and soldering, I just bought this

Speed measurement result for my Thorens TD125

by **safe1** » 30 Jul 2010 03:39

irwan_su,

does that need a reflective mark on the platter side?

by **irwan_su** » 03 Aug 2010 00:57

Yes it need a reflective mark on the platter side, like in this picture .

by **1200y3** » 04 Aug 2010 14:06

Show me some evidence that a power company has poorer line frequency than we can do ourself. If speed inaccuracies are a concern then a test record with 400HZ and 500hz tones are measured up against WWV (NIST) and a frequency counter, which are very cheap for the accuracy today.

How do you know that strobe dots are accurate then?

A portable battery operated strobe is great for the convenience, but how would you know if it slips off frequency?

And if you are thinking about a strobe because you simply want a clearer display then a plug in LED nightlight works excellent. For $2 you're in business. But if you use a neon lamp with a rectifier, you won't get fooled, because all bands are visible, but in motion, when one band is locked.