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Old 26th November 2010, 08:14 PM   #1391
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denis thank you very much for helping me out on that one and by the way don't be sorry about your english i am french from quebec and ihave the same difficulty,but we were able to communicate and understand each other in something we both love it is absolutly fantastic so thanks again pierre
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Old 4th January 2011, 03:22 AM   #1392
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Default BOM for Aleph Power Supply (from chipamp.com)

I purchased the Aleph boards (amplifier and power supply boards) at chipamp.com but the BOM for the power supply board (AMP-PS-PCB) does not seem to exist. I emailed chipamp.com but have yet to get a reply. By any chance does anyone have the BOM for the Aleph power supply board? If so, it would be great if they could post it.
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Old 4th January 2011, 08:38 AM   #1393
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Quote:
Originally Posted by msaywitz View Post
I purchased the Aleph boards (amplifier and power supply boards) at chipamp.com but the BOM for the power supply board (AMP-PS-PCB) does not seem to exist. I emailed chipamp.com but have yet to get a reply. By any chance does anyone have the BOM for the Aleph power supply board? If so, it would be great if they could post it.
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Old 14th February 2011, 04:06 PM   #1394
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Default Mini Aleph

Just a couple of questions to this very interessting amp:

- On the schematic of the A30... All i need for the Mini-A is the part on the left side? Including Q6 and Q7?
- The Parts on the right are for upgrading to an A30, right?
- As i can see, the neg input must be grounded for unbalaced input... Think i read this anywhere here... P-grounded or S-grounded?
- In the schematic are some resistors called "TBD" as value. What do they mean?

Thats it so far... Just began to route the layout...

Last edited by Xandrell; 14th February 2011 at 04:15 PM.
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Old 14th February 2011, 04:17 PM   #1395
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Xandrell, to what schematic are you referring? For a mini all you need is the front end (P channel differential pair and CCS) and a pair of output devices (One for the active current source the other for the gain device and maybe the current limit circuit (two resistors and an npn bipolar.)
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Old 14th February 2011, 06:11 PM   #1396
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The schematic im reffering on is now attached.

I think its from BrianGT... But not quiet sure bout that...
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Last edited by Xandrell; 14th February 2011 at 06:23 PM.
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Old 14th February 2011, 06:39 PM   #1397
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Yes, That's Brian's schematic. The mini is the main body of the schematic, located on his main board. The other parts are on the output boards he supplies. At the sale price of $7.20 it's hardly worth the effort to design your own boards unless you want to learn how.

TBD stands for To Be Determined.
R6 may be used to help correct offset if there is a mismatch in Q1 and Q2. You don't need it if you get a good match.
R12 sets the AC current gain. You'd be at 50% with 1K
R13 fine tunes the bias in the output stage. The higher the value the greater the bias.
R17 is a protection circuit part that sets the Q6 current when the protection kicks in. 392R has been used before. I used 1K and 1k2 for R21.

Connect the negative input to the signal ground for single ended operation.
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Old 14th February 2011, 06:52 PM   #1398
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Thanks to this point man... Wishing german posters would try to help like the people here ^^

One part is to learn how (designing and which function every part has ^^). On the other hand im living in germany and 15 bucks for shippment is far more expensive than having fun designing and etching the layout at work for free

So, back to the initial question My "part of work" is to design and route the schematic as shown above until R23-R26 for a Mini-Aleph?

Just hoping it will work from a 2x12V/100VA toroid per channel

Last edited by Xandrell; 14th February 2011 at 06:56 PM.
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Old 14th February 2011, 07:24 PM   #1399
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Yes, just the left side of the schematic will be a mini-Aleph. The two sub-circuits to the right of R23 are the output boards used in a larger Aleph.

That transformer won't give you much room for anything but a big capacitive filter (a CLC or CRC might eat up a lot of rail voltage) but otherwise will work and give you ~16V rails.

Try around 30K for R13 (using an MPSA-18 for Q4,5) to give you ~25W total dissipation to keep your transformer operating at roughly half its rated VA. When ordering, pick a few values between 20K and 47K to try.
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Old 15th February 2011, 05:14 PM   #1400
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Would there be any disadvantage in using the original ztx450 without changing R13?
And would it also be possible to use a trimpot for the "TBD"-labelded resistors for some fine-tuning?
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