Some LME49600 implementations

[Avro_Arrow]

Your right!
Thanks for catching that...
 
Quote:

Avro_Arrow,
 
I've just been looking at your circuit for the modular boards you were working on, the servo opamp has the inverting and non-inverting inputs swapped, if I'm not mistaken. The amp output should connect to the non-inverting input as the servo feedback goes to the amplifier proper's inverting input.
 
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[wakibaki]

Ordered 10 boards.
 
I went for minimal changes, just put the slots in the groundplane, fixed the relay transistor footprint and moved the silkscreen around a bit to improve legibility, some of the legends were missing bits because they were on top of vias.
 
 

 
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[Misterrogers]

I'll take one of those when they land

 

[J-Pak]

I got the hum issue fixed. The amp sounds great. Rather than go into a description (since I am not sure I could describe it), I'll just say I doubt I would be able to tell it apart from a Gilmore Lite (Dynalo) if I was blind folded. It has more than enough gain with the prototype DAC I'm using with my HE-500.
 
Still using it uncased, and not finding the heat is much of an issue. I will probably case it up in a single box with an ODAC or something similar and have myself a pretty nice laptop amp/DAC one box solution.

 

[wakibaki]

Excellent, J-Pak. Thanks. Praise indeed.
 
I'm expecting the new boards in a bit over a week. Naturally I'll want to build one to verify them before letting any go, but this is unlikely to take more than a day.
 
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[wakibaki]

Boards came back yesterday, unfortunately I spent most of the day in hospital.
 
About 3 weeks ago I had radioactive iodine treatment to kill off my overactive thyroid, but it seems that despite that thyroxine has built up in my body to the point where it is causing an irregularity in my heartbeat (atrial fibrillation).
 
I'll try and get one built later today.
 
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[Misterrogers]

Sorry to hear about your health issues Wakibaki; take care of yourself first.

 

[J-Pak]

Sorry to hear that wakibaki, hope you get sorted out and feeling better. Hopefully you won't need anything long term for the A. Fib

 

[wakibaki]

Thanks for the good wishes, guys, a couple of days of beta-blockers and I'm feeling mostly recovered. It's just a been bit exhausting because it's hard to sleep when your heart keeps saying 'listen to me, listen to me'
 
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[fzman]

i am recuperating from a quadruple bypass, and remember having a-fib pretty regularly when i was in hospital, post-op.  not much fun..  hope you feel better

 

[wakibaki]

Thanks fzman. Good to hear you are recuperating. I'm back to what passes for normal for me.
 
I have built up one of the new boards, it works fine, hum has been eliminated. I'll post some measurements soon.
 
I wrote a query via the feedback form inquiring about selling boards, but I haven't had a reply. Does anybody know how this works?
 
Boards will be £5 flat rate (5 Pounds UK) including worldwide P & P (and Paypal charges). This is ~$7.85 US at current exchange rates. If you send me a PM I will send you a paypal invoice, but please wait until I confirm that I am have fulfilled any forum requirements. There are 10 available in this batch.
 
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[fzman]

Thanks for the kind thoughts.  Your design looks interesting, and i have a bunch of those National Semi parts already, as I had tried to build some regulated power supplies with them, and could not get them to settle down - it was about 2 years ago, and i would probably do it a bit differently now, but i have not had the need to. That said, it looks like a bit too much surface mount for me right now, as i would solder each part individually, not by reflow....
 
oncve again, i hope you feel better and things come back to an acceptable level of normal...

 

[Misterrogers]

Hey All - finished my board to day and fired it up, no output. I'm using the latest batch. A couple of questions; 
 
 
1) Does Q3 still need to be flipped? I didn't. I did switch the polarity of C27 as recommended.
2) How do I bypass the protection?
 
Any other troubleshooting suggestions would be greatly appreciated. I'm a noob. Also, I assume J3 is input - yes?

 

[wakibaki]

Yes J3 is input. Q3 no longer requires to be flipped. The simplest way to defeat the protection is to short across the collector and emitter of Q3. Holding the board so that the legends read correctly from left to right, the topmost pin of Q3 is the emitter and the pin on the left is the collector. You should hear the relay click (quietly) if it hasn't flipped already.
 
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[Misterrogers]

Thanks mate. What would cause the need to defeat the protection?