I saw lots of what looked like good Tektronix and HP Oscillocopes going for as little as $100 on ebay.
My dad was real thrilled when he was the only bidder on a highly outmoded HP oscilloscope from his job back in the late 70's. It must have weighed 300 lbs, was mostly tubes. It was on a huge wheeled cart, since you couldn't really carry it.
It still worked great but my dad said that it was just too big to be used at work anymore. He got it for $35 bucks.
It took few minutes to warm up, but then worked fine.
****
I can't imagine that you would need a very high end scope for audio amp work. Just something that could see what sorts of signals you were getting should be good enough. So are these old $100 solid-state scopes good enough. Or are you getting what you paid for?
My dad was real thrilled when he was the only bidder on a highly outmoded HP oscilloscope from his job back in the late 70's. It must have weighed 300 lbs, was mostly tubes. It was on a huge wheeled cart, since you couldn't really carry it.
It still worked great but my dad said that it was just too big to be used at work anymore. He got it for $35 bucks.
It took few minutes to warm up, but then worked fine.
****
I can't imagine that you would need a very high end scope for audio amp work. Just something that could see what sorts of signals you were getting should be good enough. So are these old $100 solid-state scopes good enough. Or are you getting what you paid for?
Nice work guys....
This thread has been very interesting (apart from some polemic deviation 😉 ) and has definitely put a regulated GC in my to-do-list.
For now I'll complete my valve buffered one following Joe Rasmussen's schematic but will eventually convert it (or build another one?) with Pedja's or Carlos' schematics.
Cheers
Andrea
This thread has been very interesting (apart from some polemic deviation 😉 ) and has definitely put a regulated GC in my to-do-list.
For now I'll complete my valve buffered one following Joe Rasmussen's schematic but will eventually convert it (or build another one?) with Pedja's or Carlos' schematics.
Cheers
Andrea
Member
Joined 2002
Re: Re: Re: Re: Weekend update
Sure.
As I said, I'm using double regulation.
You are free to use the regulator you whant.
Be creative, don't stick to a schematic.
jackinnj said:
Sure.
As I said, I'm using double regulation.
You are free to use the regulator you whant.
Be creative, don't stick to a schematic.
Panelhead said:
This is my first experience with the AD8620, so it's just my first impression, not definitive.
I hit it with +/- 14.5v, I know it's over the top, but I've heard some people saying (P-A?) it works fine.
I also have the feeling that it may go better with a lower voltage, next time I'll try it.
Bob03 said:
Let's stay with rev_3, I don't like filters, but I know what J-P is talking about, he's right...
It could be included as optional, with a comment (*).
Bob03,
You are really helping with those nice, clear, up to date drawings.
Thank You
Maybe someday soon there will be a PC board 😀
You are really helping with those nice, clear, up to date drawings.
Thank You
Maybe someday soon there will be a PC board 😀
DC blocking caps
Guys,
I'm interested to know if this amp can be built without the DC blocking cap in between the buffer and power amp. Could a servo be used to take care of the total DC offset built up between input and output?
Also, what are the benefits of using a low value output resistor instead of a zobel network?
Cheers,
Arnie
Guys,
I'm interested to know if this amp can be built without the DC blocking cap in between the buffer and power amp. Could a servo be used to take care of the total DC offset built up between input and output?
Also, what are the benefits of using a low value output resistor instead of a zobel network?
Cheers,
Arnie
Re: DC blocking caps
as the OPA627 has "offset null" you can insert a trimmer resistor on the appropriate pins and null out any DC --
Zobel or 0.22R -- depends upon your application, the load and cables you are using.
arniel said:
as the OPA627 has "offset null" you can insert a trimmer resistor on the appropriate pins and null out any DC --
Zobel or 0.22R -- depends upon your application, the load and cables you are using.
Re: DC blocking caps
That cap is there to remove DC from the source.
The OPAs have very low DC offset, no problem here.
You can go without it if you trust everything you connect to your amp.😀
It sounds better.😀
arniel said:
That cap is there to remove DC from the source.
The OPAs have very low DC offset, no problem here.
You can go without it if you trust everything you connect to your amp.😀
arniel said:
It sounds better.😀
I know that BrianGT has taken an interest in regulated supplies so look out for a possible PCB! 😉
How cool...
We make the schematics, have the ideas, all the work and Briand/PD sell the PCBs.
This thing is really begining to stink.😡
What happened to diy?😱
Only kit builders here?🙄
We make the schematics, have the ideas, all the work and Briand/PD sell the PCBs.
This thing is really begining to stink.😡
What happened to diy?😱
Only kit builders here?🙄
Pedja said:
What you've read is me and my anger because this place is full of group orders now, and people advertizing what they sell.
Sorry, forget it.
But read this anyway:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=36338
I've just found out that Peter keeps provoking me with posts like this:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=36398&pagenumber=4
I don't know why he does this, it escapes me.
I don't like this, if he stops provoking me, I'll shup up and be quiet.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=36398&pagenumber=4
I don't know why he does this, it escapes me.
I don't like this, if he stops provoking me, I'll shup up and be quiet.
Not even close to what I just have to write, but the part of it
Carlos, I do not have a problem with Peter. As I can read, this has nothing with Peter.
I’d like to warn you: it is not any polite (slightly speaking) to send private mail publicly whatever is inside, so it is out of mind to deal with the content of such mails.
You should know that the most known and most successful Scott’s project started as the forum group project that he commercialized afterward. Annoying by that step at least one of the main contributors in that project. But I do not have a problem with it, it was not me, though I do understand the case. Anyhow, I do not like at all when people blame the others for the things they themselves do.
So, now really, forget the post that you have linked.
What I do have as a problem now is someone’s idea to commercialize my own work. Does not informing me about it at all. That is a really big problem for me. If anyone wants to deal with PCB for regulated GC supply, he/she is free to continue with – contribute in this thread.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=35442&perpage=10&pagenumber=3
Or to take his own work to design something, even something trivial like usage of two LM338 to regulate GC PS, and than to sell it with the aura of someone who was the first who found it to be better than what is/was in the circulation previously. Might be enlightening experience.
Pedja
Carlos, I do not have a problem with Peter. As I can read, this has nothing with Peter.
I’d like to warn you: it is not any polite (slightly speaking) to send private mail publicly whatever is inside, so it is out of mind to deal with the content of such mails.
You should know that the most known and most successful Scott’s project started as the forum group project that he commercialized afterward. Annoying by that step at least one of the main contributors in that project. But I do not have a problem with it, it was not me, though I do understand the case. Anyhow, I do not like at all when people blame the others for the things they themselves do.
So, now really, forget the post that you have linked.
What I do have as a problem now is someone’s idea to commercialize my own work. Does not informing me about it at all. That is a really big problem for me. If anyone wants to deal with PCB for regulated GC supply, he/she is free to continue with – contribute in this thread.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=35442&perpage=10&pagenumber=3
Or to take his own work to design something, even something trivial like usage of two LM338 to regulate GC PS, and than to sell it with the aura of someone who was the first who found it to be better than what is/was in the circulation previously. Might be enlightening experience.
Pedja
To clear the air a bit I must apologise for an inaccuracy in my previous post. Brian was asking me about the buffered GC NOT the regulated PSU.
Aplogies to all concerned. 😱
Aplogies to all concerned. 😱
i think i will order a 100 pieces of our own (highly proffesional doublelayer) pcb......and just give them away for free....no make that 200, i'll just check the costs and then i'll decide.........🙂
Carlos
after all I was reading about your regulated amps, I was thinking alot about this topic and I am sure, I have to try it.
I believe in this concept, after playing a little bit with duncans amp tools, the psu-simulator.
Just use 50 V trafo 1R, a 2000uF cap after the rectifier and put at the end a stepped current load. Define the step from some mA up to 2-3A after 2 seconds. I know, the trafo is not correct, as it has no center tap.
Then simulate and look what happens with V(I1), specially the transient.
It is not a big difference, weather you use 10000uF Caps or 2000uF.
It is even not a big difference, when you use a "stronger" trafo (lower R).
Regulation must be the way! Maybe not for the famous first watt, but I will try it soon.
What regulators to use, with no separate secondaries, with a single center tap?
Franz
P.S.
The attachment shows a hardcopy of a simulation with 1000uF
after all I was reading about your regulated amps, I was thinking alot about this topic and I am sure, I have to try it.
I believe in this concept, after playing a little bit with duncans amp tools, the psu-simulator.
Just use 50 V trafo 1R, a 2000uF cap after the rectifier and put at the end a stepped current load. Define the step from some mA up to 2-3A after 2 seconds. I know, the trafo is not correct, as it has no center tap.
Then simulate and look what happens with V(I1), specially the transient.
It is not a big difference, weather you use 10000uF Caps or 2000uF.
It is even not a big difference, when you use a "stronger" trafo (lower R).
Regulation must be the way! Maybe not for the famous first watt, but I will try it soon.
What regulators to use, with no separate secondaries, with a single center tap?
Franz
P.S.
The attachment shows a hardcopy of a simulation with 1000uF
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