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Old 18th July 2013, 08:03 AM   #41
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I knew that people will at last notice this excellent PSU! I think that PMI will have pcbs soon available.
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Old 18th July 2013, 10:00 AM   #42
vgeorge is offline vgeorge  Greece
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I' m in for a couple of boards too, if they become available.
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Old 18th July 2013, 03:16 PM   #43
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Me too for 2 boards.
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Old 18th July 2013, 04:37 PM   #44
PMI is offline PMI  United States
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@touchdown:

Thanks for the compliment and your interest... of course, remember that all the original work was done by MrEvil, who is kindly sharing his design w. the rest of us...

I have seen this type of regulation before, just not in audio, which gives me some confidence that this will work out well.

VSSA (which is why I started on this), definitely sounds better with a clean supply. I have tested with a couple conventional power supply configurations, and with a large Tektronix linear bench supply. The difference is small, but noticeable in a controlled a-b test. More so with better speakers...

In General:

I have a few spare boards from the initial batch of ten, and I can always reorder, if there is an interest.

Electrical and noise testing looks good so far, but I am not done yet.

Ripple and rectifier noise is below measurable levels. In the presence of 10-15mV of HF noise from radio etc., and on my old 100MHz Tektronix 2221A, with conventional 10-x probes, I cannot measure below 20mV.

I have found three small mechanical problems, two with incorrect hole size, and one was a plain error on my part, w. hole spacing. The incorrect hole size is an indirect result of getting boards at a discount. Normally there is a tooling charge of >$100 per order. Without this, they basically run whatever you send them. And, my drill file did not translate cleanly. As a result, two large hole sizes defaulted to the smallest size specified.

Availability:

If all works out well, I will definitely re-order, so if you are reading this, you won't miss anything if you don't get a board from the first batch. It will just take an extra 2-3 weeks. To get boards at a decent price, I can't specify lead times less than 2 wks, or less than 3-5d shipping.

A GB may not make sense. I am willing to look into it, but: As long as we operate under a discount, there is little cost savings until about quantity 100 (without the discount, sure, a GB is a good deal). At the same time, the first people showing an interest have to wait the longest time, which does not seem fair to me. So, not sure if it is worth it to save $1-2 per board.
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Old 18th July 2013, 05:10 PM   #45
PMI is offline PMI  United States
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@Merlin the magician - for delivery to a "future state in Europe", you must use your own special powers, the rest of us mortals are a bit limited in that regard, as follows...

Recent experience has shown that small pkg (or padded envelope) delivery to CE countries may take up to two weeks... Cost by regular mail in a padded envelope to Europe is as follows:

2oz (1 board): $2.90
3oz (2 boards): $3.75
4oz (3 boards): $4.60
5oz (4 boards): $5.45

One board can probably be mailed in a regular envelope w. a 'Non-machinable" surcharge (rigid contents), for $2.25.
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Old 18th July 2013, 06:06 PM   #46
vgeorge is offline vgeorge  Greece
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I am not in a hurry, so kindly let me know when you are going to have some boards available.
As for shipping, a few bucks more or less is not a big difference.
I intend to use them on a VSSA too.
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Old 19th July 2013, 06:04 PM   #47
PMI is offline PMI  United States
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Quote:
Originally Posted by vgeorge View Post
I am not in a hurry, so kindly let me know when you are going to have some boards available.
As for shipping, a few bucks more or less is not a big difference.
I intend to use them on a VSSA too.
I have a few from my original order that are not already spoken for. If there is enough interest, I intend to order another batch.

Basic testing is done, the boards work, most of my remaining testing is to make sure that the selected resistor values are correct, where to set the dropout voltage, and measuring a few parameters so other people can compare results. I plan to finish testing this weekend.

Two sets of holes on the original boards have to be drilled out to fit. I plan to do this for any I send out.
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Old 19th July 2013, 06:24 PM   #48
PMI is offline PMI  United States
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Default TO-220 Heatsink sizes and specifications

The heatsinks were chosen for low cost. 4 of the smaller type for rectifier diodes, and two of the larger type for the pass transistor are required, total cost around $3-$4 for all six heatsinks.

The smaller heatsink footprint is 10mm deep x 15mm wide, 21-25mm in height, with a single hold-down pin that can be soldered to the board. It is a type available from various sources on the internet, ebay etc. starting at around $0.30/each.

Other similar heatsinks can be substituted up to 20-mm wide. One of the pictures below shows a couple alternatives I happened to have on hand. There is nothing unique or special about the one I chose, I simply happen to like it (and, low cost).

The larger heatsink is used for the pass transistor, and is a standard type available from any distributor such as Mouser, for about $1. In the picture it is a Thermaloy 513102B02500G, rated at 11C/Watt. This is a bit more critical, and is chosen to be larger than needed for a typical class A-B amplifier. Going too cheap here, means that the dropout voltage cannot be adjusted over its full useful range. There are 3 or 4 different heights available, as well as similar heatsinks which will fit the same space.

If there is enough interest in the circuit board to warrant another order, I will do my best to keep a few sets on hand.
Attached Images
File Type: jpg TO220_Heatsink1.jpg (235.4 KB, 558 views)
File Type: jpg TO220_Heatsink2.jpg (219.6 KB, 538 views)
File Type: jpg TO220_Heatsink3.jpg (31.6 KB, 521 views)
File Type: jpg TO220_Heatsink4.jpg (308.0 KB, 524 views)
File Type: jpg TO220_Heatsink5.jpg (16.7 KB, 511 views)
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Old 19th July 2013, 06:56 PM   #49
freeman is offline freeman  United States
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Default future request

Hi Pete,
In addition to the one I need for the VSSA, I will need at least 4 more. Upcoming projects include low power VSSA as well as a preamp and active crossover projects which need 15v rails. I would like to try all these with your board. Thanks.
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Old 19th July 2013, 11:05 PM   #50
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Hi Pete, I would like 2 pcbs, if/when they're available, or to add my name to a future order list - thanks.
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