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Millett "Starving Student" hybrid amp - Page 193

post #2881 of 6048
4/9/09 at 9:33pm
Quote:
Originally Posted by Fred_fred2004 View Post
Heres some pics
I was using a Jaycars ABS box (HB5970) so the heat sinks were insulated from the circuit, the switch has abuilt in LED ( SP0704) which makes life simple, the home made pcb is sitting flat on the case's base, So I didn't need to stand it clear of any metal. The Mosfets have clear heatshrink on them but its hard to see (because its clear). The amp is great well worth building
cheers
Fred
Thx Fred for the photos but there are still a few questions I have:
1. I still don't get how you insulated the MOSFETs as I don't see any heatsinks and the case is ABS (I probably missed them in one of the photos). I know you have heatshrinked the MOSFETs as well.
2. Where would you connect the LED circuit to?

You've been heaps of help. Much appreciated.
-CaptHowie
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post #2882 of 6048
4/9/09 at 10:02pm
Quote:
Originally Posted by CaptHowie View Post
Thx Fred for the photos but there are still a few questions I have:
1. I still don't get how you insulated the MOSFETs as I don't see any heatsinks and the case is ABS (I probably missed them in one of the photos). I know you have heatshrinked the MOSFETs as well.
2. Where would you connect the LED circuit to?

You've been heaps of help. Much appreciated.
-CaptHowie
His FETS are on the heatsinks mounted on the top of his case.
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post #2883 of 6048
4/9/09 at 10:41pm
Quote:
Originally Posted by CaptHowie View Post
Thx Fred for the photos but there are still a few questions I have:
1. I still don't get how you insulated the MOSFETs as I don't see any heatsinks and the case is ABS (I probably missed them in one of the photos). I know you have heatshrinked the MOSFETs as well.
2. Where would you connect the LED circuit to?

You've been heaps of help. Much appreciated.
-CaptHowie
V3nom is spot on, you don't need to insulate the mosfets from the heatsinks because they are mounted on plastic.

The LED look at the back of the switch the Rled is in some black heatshrink



here is the pcb I've tried to show how the led is connected
cheers
fred
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post #2884 of 6048
4/10/09 at 12:51am
I'm building this now,can someone double check the way I'm reading the schematic?

Do R3 and R9 go to pin 1 (gate) of the MOSFETs?
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post #2885 of 6048
4/10/09 at 1:59am
Quote:
Originally Posted by penneydude View Post
I'm building this now,can someone double check the way I'm reading the schematic?

Do R3 and R9 go to pin 1 (gate) of the MOSFETs?
Yes penneydude, that's correct. Solder the resistor lead directly to pin 1 of the mosfet to keep their distance short.

zk
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post #2886 of 6048
4/10/09 at 2:01am
Quote:
Originally Posted by zkool448 View Post
Yes penneydude, that's correct. Solder the resistor lead directly to pin 1 of the mosfet to keep their distance short.

zk
Thanks! I'm so close...
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post #2887 of 6048
4/10/09 at 2:48pm
One more dumb question - I can't find the exact power supply on ebay, but I do see a similar 48v power supply that offers 1.25amps. Since the original one mentioned only offers .38 amps or so, will this be okay?

Edit - oops, I've just found the proper power supply for cheaper on eBay after all. Disregard!
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post #2888 of 6048
4/10/09 at 11:14pm
Quote:
Originally Posted by cactus friend View Post
One more dumb question - I can't find the exact power supply on ebay, but I do see a similar 48v power supply that offers 1.25amps. Since the original one mentioned only offers .38 amps or so, will this be okay?
I use the 1.25 amp unit. It works great, without the stuttering the 380ma one can cause.
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post #2889 of 6048
4/11/09 at 12:05am
what is the minimum or recommended wire gauge for running wires to the fets and tube sockets?
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post #2890 of 6048
4/11/09 at 2:09am
Quote:
Originally Posted by metal112524 View Post
what is the minimum or recommended wire gauge for running wires to the fets and tube sockets?
I don't think there is a minimum or recommended awg size but if you want to put a size to it i guess the minimum gauge could be equal to the leads on the resistors/capacitors you use.
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post #2891 of 6048
4/11/09 at 2:11am
ok well is 22awg ok? or maybe 2 strands per lead?
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post #2892 of 6048
4/11/09 at 10:37am
22awg is more than fine.
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post #2893 of 6048
4/11/09 at 11:24am
PCB's have shipped. It may take a few more days for me after they get here, though - this comes right on top of IRS time.
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post #2894 of 6048
4/11/09 at 11:32am

Worked the first time!

Ok, finally got around to building it.



True starving student as the tubes were the only things purchased.(thanks v3nom) The rest of the parts came from old ups and computer power supplies. Jacks are from a sound card and the pot is from an old stereo. All wiring was done with Cat5E, p2p so I can upgrade parts as I aquire them. Very, very slight hum when nothing is attached to the input but dead silent when the mp3 was attached. I’ve been listening for 2hrs now and its amazing. Thanks Pete and everyone else for all the info and upgrade ideas.
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post #2895 of 6048
4/11/09 at 11:59am
Quote:
Originally Posted by tamasic1 View Post

True starving student...
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