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Chip Amps Amplifiers based on integrated circuits

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Old 4th April 2012, 11:43 AM   #11
redjr is offline redjr  United States
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Location: Danbury, CT
Quote:
Originally Posted by AndrewT View Post
+-60Vdc should be approaching 200W into 8r0 if you build it right.

+-50Vdc is the norm for a 100W into 8r0 ClassAB Power Amplifier.
According to the seller, my PSU outputs +-60v which can be used (in parallel) to supply both V & Vcc requirements on the amp PCB. I have attached the schematic below.

It appears the +-60v supply the LM4702 module on pins 13-15, and the +-45 Vcc powers the output transistors. Am I understanding that correctly?
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Old 6th April 2012, 12:09 AM   #12
redjr is offline redjr  United States
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Default Another update

Hi all -

Quick update and some pics. I've finally decided on the enclosure layout of the modules and managed to get everything semi-mounted on their stand-offs. Also made some basic (no load) voltage measurements of the tranny and PSU. All voltages were spot-on as advertised! Continued to wire up what I could. Still waiting on some better binding posts to arrive before starting to drill the rear deck. Also need to get some fuses for the IEC connector. Maybe by the weekend. Attached are a few pictures from today.

My Photobucket site has been updated with more pictures if you care to see more detail of the build.
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Old 6th April 2012, 03:46 AM   #13
redjr is offline redjr  United States
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For some reason the pics did not show in my post above. Here they are.
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File Type: jpg P1060609.jpg (525.1 KB, 455 views)
File Type: jpg P1060612.jpg (630.8 KB, 360 views)
File Type: jpg P1060615.jpg (445.7 KB, 323 views)
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File Type: jpg P1060621.jpg (510.2 KB, 117 views)
File Type: jpg P1060625.jpg (447.4 KB, 168 views)
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Old 6th April 2012, 06:23 AM   #14
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would look better if the wires were all over the place like everyone elses

Nice setup so far
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Old 6th April 2012, 09:28 AM   #15
bcmbob is offline bcmbob  United States
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For future reference, remember that with a good carbide blade on a table saw most aluminum heat sinks cut like hardwood. I have used that method to custom fit HS often. It looks like there was plenty of room to get 1/16" + from one side and still have room for mounting hardware. This is in no way a criticism of your approach - just a suggestion of an alternate method to get max air flow around the fins.

Note: All shop safety rules must be applied !!
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Old 6th April 2012, 01:51 PM   #16
redjr is offline redjr  United States
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Quote:
Originally Posted by fabricated View Post
would look better if the wires were all over the place like everyone elses

Nice setup so far
Ha ha.
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Old 6th April 2012, 02:05 PM   #17
redjr is offline redjr  United States
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Quote:
Originally Posted by bcmbob View Post
For future reference, remember that with a good carbide blade on a table saw most aluminum heat sinks cut like hardwood. I have used that method to custom fit HS often. It looks like there was plenty of room to get 1/16" + from one side and still have room for mounting hardware. This is in no way a criticism of your approach - just a suggestion of an alternate method to get max air flow around the fins.

Note: All shop safety rules must be applied !!
I probably could have gone that route - had that been my only option. The issue was the PCB and heatsink are so tightly integrated. I chickened out and really didn't want to remove it to cut it down. Had I decided to still mount the HS vertical, I could have, had it been placed right up against the rear-deck. It seemed to fit there, but was still very tight once the cover was on. There are vent slots punched into the top right over where the HS is positioned now. Hopefully this will easily allow the heat to escape up and out. This obviously was not my original design, but has become an 'as-built' situation. Clearly, this is an issue that surfaced as a result of the poor QC of the case manufacturing. No criticism taken.
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Old 6th April 2012, 03:35 PM   #18
bcmbob is offline bcmbob  United States
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Sounds good. Looking forward to your progress reports.
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Old 6th April 2012, 03:36 PM   #19
redjr is offline redjr  United States
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One other thing guys I've noticed.... maybe you can help. The leads on the toroidal are 16 AWG and seem to be pretty beefy. I've tried to find some similar gauge, 300v, and weight(thickness), but all the 16 AWG hook-up wire I find is much thinner.

I also noticed that the tranny leads have an extra white internal sheath that I guess adds some extra insulating properties to the wire. This is course adds to the overall thickness. At a minimum, I would like to find some similar size wire to go from my PSU to the amp module - where high current may be likely under some operating condition. I ordered some more wire last night that is 16 AWG, but it's hard to tell from a website, just how thick it is. I thought 16 gauge, is 16 gauge! Can anyone recommend some wire, or at least provide the right AWG markings I need to zero in on, type I should be looking for?

Suggestions, links?
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Old 6th April 2012, 03:45 PM   #20
bcmbob is offline bcmbob  United States
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I have tried to try the same thing till I realized, if the AC wires feeding the transformer were carrying the full power to the transformer, they certainly could handle the reduced amount. Now I just strip one of the many PC style power cord lying around and use that wire. I cut the transformer leads to a length that is appropriate and transition with a Euro-style screw terminal. Works for me.

I actually cut these too short but still works.

20120327_195453tt.jpg
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Last edited by bcmbob; 6th April 2012 at 03:53 PM.
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