Hi Tom,
That took you some time
A Kwak-clock requires a symmetrical power supply, and the only supply in the CD67 you could use for it is the analog supply. Not really recommended, because you will pollute the analog output section with noise from the Kwak-clock. If you'd like to test it and see if it works, you could use the voltage from C803 and C804. There's about +/- 21V there.
The best solution is to use an external supply for the clock. A small transformer with two secondaries, a bridge rectifier and two capacitors are all you need. If you want to go fancy you could even use a 7812/7912 combo to do some pre-regulation and feed the Kwak with a nice stable voltage.
I've had the same problem in the past, and I didn't want to use a dual supply voltage for a simple clock. So I decided to modify the Kwak 7 a bit and make it work on a single-ended supply. You can find the result here on my CD clock page.
Regards,
Ray
That took you some time
A Kwak-clock requires a symmetrical power supply, and the only supply in the CD67 you could use for it is the analog supply. Not really recommended, because you will pollute the analog output section with noise from the Kwak-clock. If you'd like to test it and see if it works, you could use the voltage from C803 and C804. There's about +/- 21V there.
The best solution is to use an external supply for the clock. A small transformer with two secondaries, a bridge rectifier and two capacitors are all you need. If you want to go fancy you could even use a 7812/7912 combo to do some pre-regulation and feed the Kwak with a nice stable voltage.
I've had the same problem in the past, and I didn't want to use a dual supply voltage for a simple clock. So I decided to modify the Kwak 7 a bit and make it work on a single-ended supply. You can find the result here on my CD clock page.
Regards,
Ray
I finally diagnosed my intermittent problem with my display dying and the disc spinning either backwards or very fast clockwise this evening. Seems the 5v regulator I built for the decoder has a loose joint somewhere cos I can apply pressure to it in a certain direction and everything springs back into life. Very happy to have worked that one out!
Now I just need to fix it.
Now I just need to fix it.
Thanks Ray however my clock didn't work, according to Kwaks instructions I should set pin 3 of comparator using pot to +0.5v to +0.6v however I could only get -4.5v to -13v (I didn't connect output to xtal/digi processor circuit just in case the pin 3 voltage had to eb set first- would this connected change the value of pin 3?)
Tom (Honda Z50M)
Tom (Honda Z50M)
Ray, I have made a +/-5v supply and amended the clock circuit (hopefully it should be attached below)
If you could cast your eye over it and let me know if this will be ok with regards to noise etc (I get +0.5v now on pin 3) I'll rebuild the clock and try again.
Also using the +/- 19V from the Elna's is that going to induce noise and is it of an acceptable level (will the added benefit of the clock out way the additinal noise?)
Thanks
Tom (Honda Z50m, still not heard anything from forum masters with regards to resetting my password)
If you could cast your eye over it and let me know if this will be ok with regards to noise etc (I get +0.5v now on pin 3) I'll rebuild the clock and try again.
Also using the +/- 19V from the Elna's is that going to induce noise and is it of an acceptable level (will the added benefit of the clock out way the additinal noise?)
Thanks
Tom (Honda Z50m, still not heard anything from forum masters with regards to resetting my password)
Just to update as the new parts have now optimised: the above mods to the DAC and decoder have really transformed the SQ. This is now a seriously good player with a wonderfully organic and natural sound. I would say it offers greater resolution than my turntable (Roksan Xerxes/Nima/Kontrapunkt B).
I mentioned above that the mods to the decoder had a greater effect than the DAC. On second thoughts – and I'm not an expert on this – maybe because of the clean power supplies to both DAC and decoder, that the resulting sound is because they are both operating optimally together.
Next up the DOS.
Hi Tom,
You have to click the 'attachment' button (the paparclip). Then you can upload an image that will appear in your message.
Do you mean LED or LCD? To indicate the power-on state of the player, I assume you mean LED?
Surely just running an LED off any of your other existing power supplies would be no issue? They're not exactly noisy components
Hi dwjames, thanks for your response.
I have a 3-box player, comprising main player in 1 box plus 2 additional boxes carrying the power supplies. In 1 of the cases carrying the power supplies I am powering an LED from a spare secondary from 1 of the transformers. But in my second case I do not have a spare secondary; so instead of piggy-backing from another source I would prefer to run a separate tx.
Clearly there are different opinions on whether running the LED via piggy-backing would introduce noise. I am not an expert, and I originally thought as you did, but my mentor in this project claims it could introduce nasties and affect SQ. I am extremely happy with the sound of the player as it is, so I am prepared to be cautious and hence go a little OTT and run the extra tx.
So, does anyone know of any sources for an integral small pcb which will carry a small tx plus the diodes, caps, regs, etc.?
Looks o.k. to me, basically it's the same circuit but then running off a +/- 5V power supply. Should work fine, you can adjust symmetry of the square-wave with the pot to 50% duty-cycle. But if you have no means of measuring that, just adjust it to 0V.
Ray