No, this clock is only a source, it can't be disiplined by another clock. Besides any other reason, there wouldn't be any point to it. This clock is designed to be precise rather than accurate. It accuracy is only ±50ppm (depending on the crystal used), no better than a standard CD player, but it's the precision that has an effect on sound quality.
I suggest you have a read here. The spread marked 'precision' in the diagrams is what the phase noise and jitter figures quantify.
I suggest you have a read here. The spread marked 'precision' in the diagrams is what the phase noise and jitter figures quantify.
I've assembled the new revision of the LJC, and I've run a few tests. Everything looks good, though the core circuit and layout is the same, so that's hardly a surprise. I've got a few more test to run, and then it should be ready.
The main difference between this version and the last is that is is now two separate boards; the clock itself and an optional AC to DC power supply. The main reason I did this is that I found the previous AC powered version impractical. I needed the clock to be very close to where it was needed, but often that would've meant stringing a 240VAC cable right through the middle of the player. Now you can put the clock where it's needed, the power supply board over near the player's standard transformer and an innocuous DC cable across the player.
Another advantage is that it has made the clock smaller, 45x50mm (2250mm2) versus 32x75mm (2400mm2) for the old version. Not a big difference, but when you're adding new stuff every bit helps.
The other big change is that a 120VAC version of the power supply will now be available. There's still not enough room on the PCB to add a voltage selector, so the 120VAC and 240VAC versions will use different transformers.
Unfortunately I'm about to head off on holiday for a month, so there won't be any kits or PCBs until I'm back. I'll order some PCBs to arrive while I'm away though, so I should be able to hit the ground running when I return. Utah powder, here I come!
Here's a photo:
The main difference between this version and the last is that is is now two separate boards; the clock itself and an optional AC to DC power supply. The main reason I did this is that I found the previous AC powered version impractical. I needed the clock to be very close to where it was needed, but often that would've meant stringing a 240VAC cable right through the middle of the player. Now you can put the clock where it's needed, the power supply board over near the player's standard transformer and an innocuous DC cable across the player.
Another advantage is that it has made the clock smaller, 45x50mm (2250mm2) versus 32x75mm (2400mm2) for the old version. Not a big difference, but when you're adding new stuff every bit helps.
The other big change is that a 120VAC version of the power supply will now be available. There's still not enough room on the PCB to add a voltage selector, so the 120VAC and 240VAC versions will use different transformers.
Unfortunately I'm about to head off on holiday for a month, so there won't be any kits or PCBs until I'm back. I'll order some PCBs to arrive while I'm away though, so I should be able to hit the ground running when I return. Utah powder, here I come!
Here's a photo:
Attachments
I've bought some parts, so more kits will soon be available. Pricing for the new design will be as follows:
- Bare LJC clock PCB: USD3.00
- Unassembled LJC clock kitset: USD25.00
- Unassembled LJP AC power supply kitset: USD15.00
A schematic and bill of materials for each PCB is included below. The part numbers are for element14, though parts should be available at any comprehensive electronics distributor. The LJC is the clock, and can be powered by 7 to 14VDC. The LJP is the optional AC to DC power supply. I can supply both 110 to 120VAC and 220 to 240VAC input versions. I'm not selling the PCBs for the LJP separately, as I only have a limited supply.
Postage will depend on the weight of your order, but will start at around USD11 for PCBs only.
- Bare LJC clock PCB: USD3.00
- Unassembled LJC clock kitset: USD25.00
- Unassembled LJP AC power supply kitset: USD15.00
A schematic and bill of materials for each PCB is included below. The part numbers are for element14, though parts should be available at any comprehensive electronics distributor. The LJC is the clock, and can be powered by 7 to 14VDC. The LJP is the optional AC to DC power supply. I can supply both 110 to 120VAC and 220 to 240VAC input versions. I'm not selling the PCBs for the LJP separately, as I only have a limited supply.
Postage will depend on the weight of your order, but will start at around USD11 for PCBs only.
I'm still waiting for some parts to finish making up the kits, but I should have them soon. At the moment it looks like I should be able to get Citizen HC49US crystals in the following frequencies:
- 11.2896MHz
- 12.288MHz
- 16.9344MHz
- 24.576MHz
- 33.8688MHz
The only one I've had trouble finding is 22.5792MHz, I should still be able to provide this value, but they'll only be generics.
@jonesjim: The kit includes everything you'll need to build the clock. Also included is two crystals per kit of whatever values you chose from the list above (subject to availability). The only things you'll need is cables and mounting hardware.
@Jnouw: No, I don't think the J304 would be a good choice. I accept PayPal.
- 11.2896MHz
- 12.288MHz
- 16.9344MHz
- 24.576MHz
- 33.8688MHz
The only one I've had trouble finding is 22.5792MHz, I should still be able to provide this value, but they'll only be generics.
@jonesjim: The kit includes everything you'll need to build the clock. Also included is two crystals per kit of whatever values you chose from the list above (subject to availability). The only things you'll need is cables and mounting hardware.
@Jnouw: No, I don't think the J304 would be a good choice. I accept PayPal.
Hi,
I just finished building this one, I try to test it with a cheao DSO (Hantek 6022) and what I am getting from the DSO frequency count is not a constant number, it keep bouncing up and down aroung the claimed clock rate from the crystal 16.9344mhz, never stablized to one number, is this correct ?
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I just finished building this one, I try to test it with a cheao DSO (Hantek 6022) and what I am getting from the DSO frequency count is not a constant number, it keep bouncing up and down aroung the claimed clock rate from the crystal 16.9344mhz, never stablized to one number, is this correct ?
Discrete Low Jitter Clock Board: Only Citizen HC49US crystals?
Dear amc184:
In your LJC board it´s obligatory to use the Citizen HC49US crystals, or I may solder in your creation the Philips crystal I have inside my Marantz CD94 player?
Why you do not make a board it allow use the magnificent Tentlabs Crystal Clocks?
Many thanks in advance for your comment,
Antonio
Dear amc184:
In your LJC board it´s obligatory to use the Citizen HC49US crystals, or I may solder in your creation the Philips crystal I have inside my Marantz CD94 player?
Why you do not make a board it allow use the magnificent Tentlabs Crystal Clocks?
Many thanks in advance for your comment,
Antonio
@sensphoto: Thanks, I've added you to the list.
@Wungun: I usually use SMB connectors, but that pattern will accommodate a variety of other Rf connectors, such as SMA, SMC, MCX, MMCX etc. This is the one the kit includes.
@acccruz: I mainly use the Citizen HC49US crystals because they're one of the few brand name crystals I can get in the frequencies I need. You can use the player's original crystal, but use caution. Crystals are heat sensitive, and by the time it's been soldered, desoldered and then soldered again it could well be damaged.
A Tent Clock is a crystal oscillator, not just a crystal, and is not suitable for this kit. This kit should outperform a Tent XO.
@Wungun: I usually use SMB connectors, but that pattern will accommodate a variety of other Rf connectors, such as SMA, SMC, MCX, MMCX etc. This is the one the kit includes.
@acccruz: I mainly use the Citizen HC49US crystals because they're one of the few brand name crystals I can get in the frequencies I need. You can use the player's original crystal, but use caution. Crystals are heat sensitive, and by the time it's been soldered, desoldered and then soldered again it could well be damaged.
A Tent Clock is a crystal oscillator, not just a crystal, and is not suitable for this kit. This kit should outperform a Tent XO.
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