Re: Kwak clock
Hi Jim,
The FET oscillator outputs a sine wave and the AD8561 comparator transforms this into a square wave. This is a better waveform to use as a clock signal because it has steep edges. The duty-cycle is the ratio between the on-time and total period time of the square wave. If the on and off times are equal, the duty-cycle is 50%. With the trimmer you can set the level at which the comparator switches, and when you set the duty-cycle to 50% you know it switches exactly at the center of the sinewave.
A soundcard is not very suited to measure the clock signal. It will only measure audio signals upto 20kHz if you're lucky, and the clock is at 16934400kHz, so that won't work. The best way to set P1 if you don't have a scope is with a multimeter. Set it to measure mV DC volts and connect it to pins 2 and 3 of the comparator. Now adjust P1 for a 0mV reading. That will get you pretty close.
If you're going to connect the clock to the SM5872 DAC (pin 28) in your player, you could also do without the comparator. Inside the DAC there's a similar circuit that will convert the sine into a square wave. You can take the clock signal directly from R5, with a 10 or 22n capacitor in series.
Regards,
Ray
jimh0612 said:
Hi Jim,
The FET oscillator outputs a sine wave and the AD8561 comparator transforms this into a square wave. This is a better waveform to use as a clock signal because it has steep edges. The duty-cycle is the ratio between the on-time and total period time of the square wave. If the on and off times are equal, the duty-cycle is 50%. With the trimmer you can set the level at which the comparator switches, and when you set the duty-cycle to 50% you know it switches exactly at the center of the sinewave.
A soundcard is not very suited to measure the clock signal. It will only measure audio signals upto 20kHz if you're lucky, and the clock is at 16934400kHz, so that won't work. The best way to set P1 if you don't have a scope is with a multimeter. Set it to measure mV DC volts and connect it to pins 2 and 3 of the comparator. Now adjust P1 for a 0mV reading. That will get you pretty close.
If you're going to connect the clock to the SM5872 DAC (pin 28) in your player, you could also do without the comparator. Inside the DAC there's a similar circuit that will convert the sine into a square wave. You can take the clock signal directly from R5, with a 10 or 22n capacitor in series.
Regards,
Ray
Attachments
selo said:
Hi Selo,
Personally I think 300 euros is a lot of money for a clock, but that's from a guy who builds his own.
. You could take a look around on E-Bay for Audiocom or similar products. The Kwak-based version mentioned in the above two messages is a simple but effective beginners project if you want to build it yourself.If you have no idea about electronics, maybe it's a good idea to find someone that does, so you can get a bit of help. Do you have some experience with a soldering iron? Otherwise it's going to be difficult to upgrade the player on a component level.
Regards,
Ray
jimh0612 said:
Indeed, very expensive compared to the other components. Besides, i'm dutch
.RCruz said:
Hi Ricardo,
For CT01 you can take a 100n film cap, MKT or MKP. CT02/03/04 all couple the digital ground to the player's ground for AC signals. They can also be upgraded, although some have reported good results with bypassing them, or removing them. It all depends a bit on the input circuitry of the DAC. If your DAC already has a transformer at the input, you might consider bypassing the one in the player. Experiment is the keyword here
.C514 acts as a filter, together with R514. You could upgrade it to a polystyrene if you like.
Ray
6h5c said:
never met any Scots, but they always say us dutchies are cheap :bs:
OMG - if a Scot tells you that you are cheap that is baaaaad.
My grandad was a mixture of Scottish and Jewish. If you believe in stereotypes, that would make him the tightest tightwad on the planet.... and he was!
Although I have some Yorkshire blood (and am married to a Yorkshirewoman!!) it's not enough to stop me using the comparator.
However it is enough to make me build it myself instead of buying (sorry Brent!).
Just one more question please Ray.
The link from your site to download the eps format of the clock pcb doesn't seem to work for me.
Don't think it's anything I'm doing as I got the CD outputstage eps fine - opened in Photoshop with no problems at all.
I've nearly finished building it on tripad stripboard from Maplins but it's been a headache working out the connections for a novice, with trying to construct a groundplane out of the spare strips, and I thought I might try having a go at etching a pcb.
By the time I've bought a starter kit for about £12 from Maplins I could probably have bought a pcb but don't know where to find them on the net.
Jim
However it is enough to make me build it myself instead of buying (sorry Brent!).
Just one more question please Ray.
The link from your site to download the eps format of the clock pcb doesn't seem to work for me.
Don't think it's anything I'm doing as I got the CD outputstage eps fine - opened in Photoshop with no problems at all.
I've nearly finished building it on tripad stripboard from Maplins but it's been a headache working out the connections for a novice, with trying to construct a groundplane out of the spare strips, and I thought I might try having a go at etching a pcb.
By the time I've bought a starter kit for about £12 from Maplins I could probably have bought a pcb but don't know where to find them on the net.
Jim