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Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

LDR Pre MkII - LDR volume control and I/O switching
LDR Pre MkII - LDR volume control and I/O switching
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Old 17th March 2019, 12:03 PM   #21
zdr is offline zdr  Belgium
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Quote:
Originally Posted by rpafenberg View Post
I'll take two, what about the new power supply boards, still 5eur
Yes, ps boards available too for 5 eur.
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Old 17th March 2019, 01:30 PM   #22
SpyNet is offline SpyNet  Greece
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Any pictures of the board?
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Old 17th March 2019, 01:36 PM   #23
zdr is offline zdr  Belgium
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26495336378_35f305f171_o.jpg
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Old 17th March 2019, 01:36 PM   #24
zdr is offline zdr  Belgium
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26495336378_35f305f171_o.jpg
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Old 17th March 2019, 02:11 PM   #25
rpafenberg is offline rpafenberg  United States
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Got a bill of materials yet?
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Old 17th March 2019, 02:18 PM   #26
zdr is offline zdr  Belgium
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Quote:
Originally Posted by rpafenberg View Post
Got a bill of materials yet?
No, but all the values are printed on PCB and differences are small.
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Old 17th March 2019, 08:11 PM   #27
rpafenberg is offline rpafenberg  United States
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I see that you are no longer using the 270R voltage dropping resister for the relays. Is the relay still the same as previous versions, i.e. the AGN200A4H.

It also looks like you have dropped the four 33K resisters, the two 1.2K and 2 2.2K resisters and replace them with four 500R resisters. Also a 2.2K and a 1K resister have been added to the left side of the board.

Also, the left side of the board includes a number of power supply options and other surface mount devices that are not clear. Which, if any, are not required with the external power supply board what are the new parts that are not optional. A schematic that incorporates the changes and some part numbers would be really helpful.

Regards,

Roy
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Old 17th March 2019, 09:01 PM   #28
rpafenberg is offline rpafenberg  United States
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What about the Power supply board. Could provide a picture of the board and a list of part numbers that are not self explanatory from the board itself.

Thanks,

Roy
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Old 17th March 2019, 09:40 PM   #29
zdr is offline zdr  Belgium
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Quote:
Originally Posted by rpafenberg View Post
I see that you are no longer using the 270R voltage dropping resister for the relays. Is the relay still the same as previous versions, i.e. the AGN200A4H.

It also looks like you have dropped the four 33K resisters, the two 1.2K and 2 2.2K resisters and replace them with four 500R resisters. Also a 2.2K and a 1K resister have been added to the left side of the board.

Also, the left side of the board includes a number of power supply options and other surface mount devices that are not clear. Which, if any, are not required with the external power supply board what are the new parts that are not optional. A schematic that incorporates the changes and some part numbers would be really helpful.

Regards,

Roy
You pretty much called out all the changes.

1) SMD devices on the left are not used, unless you want to have regulators on board and drive the board with single 9V switching power supply. Never tested it.
2) 500 R replaced impedance switching resistors. No impedance switching - no need for two resistor ranges (33K and 1.2K/2,2K)
3) 1k2 and 2k2 on the left to leave empty as well, there were planned for external voltage reference and never used.
4) 270R resistors around relays are not needed any more, since PS is delivering 5V everywhere. Relays used are small signal 4.5 or 5V, same as in previous versions.
5) Since the creation of AIO board I have been making changes directly to PCB, so schematics does not exist I'm afraid. I just did not have time to repair numerous mismatches between schematics and the board.
6) power supply bom is the same, apart from the regulators - you need to use three of the same type, LM7805. There is additional option for SMD bridge if you want it, its onsemi DFS04 (or any DFS0*).
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Old 18th March 2019, 02:52 AM   #30
rpafenberg is offline rpafenberg  United States
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Well the good news, at least if you are in the US, is that it will be a bit cheaper to have you integrate the relays on the board; less DIY work and lower price. Looks like it would be better to change the transformer on the PS board to something closer to 5V. Doesn't seem to make any sense to have the PS dissipate the extra power. Have you figured out a different transformer that will fit the PS PCB form factor?
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