Great...I'm so glad that "you know". Sorry that I wasted your and my time with my post #5 reply. Apparently you already know all about the 4556 from studying all those datasheets.
It's difficult to help someone who already thinks they know all about op-amp designs, though.
Good luck with your future builds Fast Eddie D and with your eyesight issues!
It's difficult to help someone who already thinks they know all about op-amp designs, though.
If I knew all about op amp designs, I wouldn't ask the questions I ask, would I?
I know how to read a datasheet and what parameters are relevant to my designs. Sometimes I'm wrong. I try to learn. I learn a lot just reading here and if it's relevant to a design I'm working on I check it out for myself.
I'm just figuring things out that I was supposed to understand .35 years ago. That's because I spent 25 years working at the exchanges and didn't do hardly any electronics. I went after the money. It didn't turn out very well for me either in the long run, thanks to the events of 2007-2009.
So don't hesitate to point something out to me. I won't be insulted, and neither should you either.
Good luck with your future builds Fast Eddie D and with your eyesight issues!
Thanks.
I blew my eyes out with a massive corona right in my face. My sight fades in and out when exposed to bright light. Images become burned in my retina for minutes; sometimes even hours. My right eye has a damaged lens from shrapnel.
I'm working six days a week (at a TERRIBLE job with no benefits, practically no pay, no days off EVER) and desperately want to find a better situation. I make too much money for medicaid or government assistance of any kind (not that I want it). All I want is an opportunity to make an honest living, using the skills I possess. It seems like too much to ask.
I recently came across an old pay stub from 1998 that I was using as a bookmarker. Take home pay for two weeks, $4200. Insurance deduction for two weeks, $17. Now my pay stub says take home pay for two weeks, $700. No insurance!
Plus I have to hustle on the side, which just about doubles my income (yes I document and report it). Something went wrong, and I don't believe it was all my fault.
Please see an ophthalmologist (not just an optometrist), even if you have in the past.
The damaged lens should be able to be replaced. I don't know about the light problem,
but you should see an expert. Your sight is priceless.
No $$$. I have to ride out a few more years until medicare. If I die first, it won't matter much because there won't be much to fight over (I still have a real nice house). All my loved ones are either dead or estranged from me (religion).
I played big and I lost bigger. Now I live a different life.
And I am not alone either. Most of my colleagues blew out way worse than me in the Big Purge of 2007-2009. Trillions of dollars were destroyed thanks to several big banks folding. Bankruptcy courts made the remaining behemoths as whole as they could (taxpayers picked up the rest of the tab) and gave all other plaintiffs $0. Remember? It was all in the papers.
I'm the only one that didn't lose their house. High rollers, all of us.
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Maybe it's time to downsize, sell the house, and get the eye care that you need.
The cost of care would be only a small fraction of your house's value.
Thought about that. Rent is way higher than my mortgage. I would net about $250K is I sold today. That's not very much money. I have to think about how I'm going to survive if I live another 25 years (which is very likely).
At some point I'll probably try to find someone to move in with me. But I absolutely hate living with people. (Cats are OK.) I love visitors, and I love it when they leave too.
At this point I haven't given up on finding gainful employment, and I'm trying to be realistic about the obstacles. Sadly my biggest obstacle is my experience; people always say "you're overqualified" which is code for "you're a nasty old fartbutt and besides we can never pay you what you're used to."
At some point I'll probably try to find someone to move in with me. But I absolutely hate living with people. (Cats are OK.) I love visitors, and I love it when they leave too.
At this point I haven't given up on finding gainful employment, and I'm trying to be realistic about the obstacles. Sadly my biggest obstacle is my experience; people always say "you're overqualified" which is code for "you're a nasty old fartbutt and besides we can never pay you what you're used to."
In a large urban area with public transportation, there's still a good chance of finding a better job.
Keep looking, and maybe downgrade your experience in some cases, if it might help.
If you have a PhD, only say that you have a BS, etc.
How about borrowing for your medical expenses, with the house as collateral?
Also, take a look at this. Financial Aid for Eye Care | National Eye Institute
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Thanks Ray, that's the plan. And I don't get out much because I work and then go home.
I talk to a lot of people that say they might call me "some day." And I still believe they might.
Back on topic, I'm building an inverting buffer board. The panel mount board will have the network and a relay. It's more complicated than I wanted it to be, but I've been trying to conjure up a decent variable "loudness" control for a while.
And also on closer analysis of the network, the passband impedance actually varies from 2.5K (control counterclockwise) to 1.2K (control clockwise). If you powered up the circuit with the control clockwise, it was stable. Then if you turned the control clockwise, it would start to oscillate when it was turned almost all the way up. You had to turn it all the way down to get it to stop oscillating.
I talk to a lot of people that say they might call me "some day." And I still believe they might.
Back on topic, I'm building an inverting buffer board. The panel mount board will have the network and a relay. It's more complicated than I wanted it to be, but I've been trying to conjure up a decent variable "loudness" control for a while.
And also on closer analysis of the network, the passband impedance actually varies from 2.5K (control counterclockwise) to 1.2K (control clockwise). If you powered up the circuit with the control clockwise, it was stable. Then if you turned the control clockwise, it would start to oscillate when it was turned almost all the way up. You had to turn it all the way down to get it to stop oscillating.
Well I am ready to revisit this topic again, hopefully once and for all.
I did build a satisfactory board using OP275 as the buffer. While I am still going to tweak the network ( and most likely build a final board) I did get over the instability hump. I've been building a couple other circuits and I had another problem with a board that I've been using for a year that employs an OPA2134 as a buffer and x2 voltage amplifier. This circuit worked great for a year, listened every day. But I added a bass compensation circuit (separate board) and there was oscillation that I traced to this 2134 that buffers the volume control. I popped a 275 in there and it's rock solid now and definitely passes the listening test.
The moral of the story is that the OPA2134 has an Achilles's heel and it's the output stage. A complex reactive load will introduce that fatal pole that introduces instability. I'm sure there's a way around it and I hope to find out. But I don't think it's a universal chip for op amp rolling. I've read comments that the 2134 sounds "veiled" and now I wonder if it was popped into an old circuit that was far from optimized. I still have two 2134s in the signal chain in my preamp (including right at the input) and it certainly doesn't sound "veiled" at all.
I did build a satisfactory board using OP275 as the buffer. While I am still going to tweak the network ( and most likely build a final board) I did get over the instability hump. I've been building a couple other circuits and I had another problem with a board that I've been using for a year that employs an OPA2134 as a buffer and x2 voltage amplifier. This circuit worked great for a year, listened every day. But I added a bass compensation circuit (separate board) and there was oscillation that I traced to this 2134 that buffers the volume control. I popped a 275 in there and it's rock solid now and definitely passes the listening test.
The moral of the story is that the OPA2134 has an Achilles's heel and it's the output stage. A complex reactive load will introduce that fatal pole that introduces instability. I'm sure there's a way around it and I hope to find out. But I don't think it's a universal chip for op amp rolling. I've read comments that the 2134 sounds "veiled" and now I wonder if it was popped into an old circuit that was far from optimized. I still have two 2134s in the signal chain in my preamp (including right at the input) and it certainly doesn't sound "veiled" at all.
Hi Eddie. You are trying to flatten out the loudness curves at what dB levels? 70, 80, 90? . Not that I understand circuits so well, but you have any diagrams of the Yamaha circuit you mentioned?
Is this the one?
Pretty sure that's universal adage. Unfortunately wildly ignored on sites like this.
In any case, I cannot think of any time I'd use a 2134 when we now have the 1642, unless one's completely desperate to have a dip8 and unwilling to use a soic8-dip8 adapter.
No. But like the circuit linked it is continuously variable. You can set the compensation completely independent of the volume control setting. It's a passive circuit buffered at the input and output, with a blend circuit (summer with pot) on the output.
Seems simple enough, but there's been some snags. And I'm still going to tweak the curves.
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