I'll do you one better:
http://export.farnell.com/wakefield...t-sink-pcb-alum-to-220/dp/1651792?Ntt=1651792
http://export.farnell.com/wakefield...t-sink-pcb-alum-to-220/dp/1651792?Ntt=1651792
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To save time for people in the same spot as I am:
These are out of stock at the moment.
I contacted Farnell and they expect new stock in a week or two (they actually said Oct. 5th but I've noticed they sometimes receive stock ahead of schedule).
Alternatives:
- The RoHS compliant variant of the one Brian suggested (Order Code: 1219495) - which is unfortunately double the price!
- Multicomp's alternative (Order Code: 1710605) - Cheap. RoHS compliant.
- Aavid's alternative (Order Code: 1213463) - More expensive than Multicomp, RoHS compliant
There are many more that I'm sure will actually fit...
The PCB is not really designed for a center tapped transformer.
Still you could use one if you understand the schematic.
One way (probably the simplest) would be to omit the two on-board bridge rectifiers. Then use a single external bridge rectifier and connect the center tap or your transformer secondary to the PCB GND and V+ from the external rectifier to the positive side of where A1 used to be. And V- to the negative side of where A2 used to be.
There are other creative solutions too. Choose any you like, or just use a dual secondary transformer.
Cheers!
Russ
Btw, although I have already ordered mine, it might help others (and my future Buffalo projects
Not a bad idea. I have a bunch of 2" as well.
Placid blues
I just completed construction of 1 Placid and 2 Placid BP supplies. None will go lower than about 8.4 volts. The second thing I did (the first being observing two lovely green led's aglow and no smoke) was make sure I got the variable resistors in their correct locations--they are. I wish to use the one Placid at 6V for the Buffalo32S. Anyone else seeing this?
RossG
I just completed construction of 1 Placid and 2 Placid BP supplies. None will go lower than about 8.4 volts. The second thing I did (the first being observing two lovely green led's aglow and no smoke) was make sure I got the variable resistors in their correct locations--they are. I wish to use the one Placid at 6V for the Buffalo32S. Anyone else seeing this?
RossG
I sent mail to buyers about this. R10 should be 1K instead of 2K. There was an error on the BOM that got into the kits. Make that change and you will be able to get down to 6V.
I am shipping replacement resistors out to everyone.
If you want to go even lower, you could keep the 2K and use a 10K pot.
I am shipping replacement resistors out to everyone.
If you want to go even lower, you could keep the 2K and use a 10K pot.
Hi Ross, Brian and I discovered yesterday because of a cut and paste mistake in the BOM/Schematic for the Placid(not BP) that feedback resistor sent with the kits is a too high to get an output voltage lower than 2X VREF which is ~4v. So the 8.4V you are seeing there is what I would expect since the pot is 2K and the FB R is 2K the lowest gain you can get is 2.
Fortunately the solution is simple. Replace R10 with 470R and you should be able to adjust even below 6V.
Alternatively if you know you want 6V you could leave the 2K at R10 and just use a fixed 4.02K (or even a bit more, maybe 4.7K since you refs seem a bit high) resistor instead of the pot to adjust the voltage. You will actually get slightly better performance this way, because the fixed R should have somewhat lower noise.
Sorry for the mistake.
Cheers!
Russ
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Brian, Russ, Thanks for the response and the excellent customer support. I'm looking forward to hearing the B32S with these new supplies. I'd make the resistor modification tomorrow, but ugh, my wife and I are going to Yosemite and beyond to see the fall colors. So my ears will have to wait. Life is so hard.
Ross
Ross
I think you will still have the 2K for R10.
All kits from now on will have 2K R10 with 10K voltage adjustment pot.
We are simply sending people who got the 2K pots 1K for R10 so they can get down ~6V.
Brian can correct me if I am wrong here.
Again, I am very sorry for any confusion this has caused.
Cheers!
Russ
All kits from now on will have 2K R10 with 10K voltage adjustment pot.
We are simply sending people who got the 2K pots 1K for R10 so they can get down ~6V.
Brian can correct me if I am wrong here.
Again, I am very sorry for any confusion this has caused.
Cheers!
Russ
Placid Drifting...
I finished my Placids yesterday and got them both installed in my Buffalo32. Contruction went well except for one goof on my part where I installed one opamp backwards. I was able to unsolder it and got a replacement from Mouser. All seems well(sort of) except for the problem described below which affects both supplies.
I adjusted both supplies for the "default" settings of .25V(CCS) and 15v(output) which I assume are appropriate for use with the Buffalo32. Adjustments went well although if you install the supplies up close to another supply you will have a hard time coming back to re-adjust the CCS voltage because R17/18 are at the base of the heatsinks which is tough to get to when another supply is next to it. Perhaps on your next board version you could extend out some test pads?
The Problem: After running the DAC for a couple of hours I came back to notice that the entire case was quit warm. Checking the voltages again I found that both the CCS voltages and the output voltages had risen on all four channels by simmilar amounts. The CCS from .25v to ~.0278v and the output from 15.0v to ~15.5v. Aside from the fact that the heat output is considerable I am concerned that there is so much drift, especially a rise. My AC voltages measured at the inputs of the regulators are between 17.6 to 18.0.
Any thoughts?
Thanks,
Paul
I finished my Placids yesterday and got them both installed in my Buffalo32. Contruction went well except for one goof on my part where I installed one opamp backwards. I was able to unsolder it and got a replacement from Mouser. All seems well(sort of) except for the problem described below which affects both supplies.
I adjusted both supplies for the "default" settings of .25V(CCS) and 15v(output) which I assume are appropriate for use with the Buffalo32. Adjustments went well although if you install the supplies up close to another supply you will have a hard time coming back to re-adjust the CCS voltage because R17/18 are at the base of the heatsinks which is tough to get to when another supply is next to it. Perhaps on your next board version you could extend out some test pads?
The Problem: After running the DAC for a couple of hours I came back to notice that the entire case was quit warm. Checking the voltages again I found that both the CCS voltages and the output voltages had risen on all four channels by simmilar amounts. The CCS from .25v to ~.0278v and the output from 15.0v to ~15.5v. Aside from the fact that the heat output is considerable I am concerned that there is so much drift, especially a rise. My AC voltages measured at the inputs of the regulators are between 17.6 to 18.0.
Any thoughts?
Thanks,
Paul
Shunt regulated supplies generate a lot of heat. You must be sure to provide enough ventilation. This alone is a good reason to space them out a little bit. After the supply is at operating temperature, and readjusted, the voltages should remain stable.
PS: I deleted the duplicate post on our support forum so that answers can be found.
PS: I deleted the duplicate post on our support forum so that answers can be found.
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