Nelson Pass said:
Hehe . . . Papa, you should worry about shortage of time.
Grey knows that here are many PCB adicts.
People who build musical instruments can do finish carpentry with one hand tied behind their backs.
(That's not saying that we're into bondage...)
I confess that I don't understand why people act as though there's something mystical about printed circuit boards. Really. Go back and read what I've said. Admit it...it's 95% common sense. What? People need to have it pointed out that you should be able to read the part value? Hmmm...I already knew I was out of step with a large number of my fellow Americans, but...I mean...c'mon guys! Yet, people keep begging for The Secret To Making Printed Circuit Boards.
Uh, well, the secret is that you get a board, contrive a pattern on it, etch it, and you're done.
Okay, now that I've told you The Secret, I'm gonna have to shoot you.
Oh, I forgot the part where you pour something tasty at the end of the process. Lagavulin works for me. Or Highland Park. Or Talisker.
It's a little weird to me that people who do really random point-to-point with stuff squished into a space the size of a golf ball believe that the same components will suddenly burst into uncontrolled oscillation if placed on FR-4.
Sigh.
Grey
(That's not saying that we're into bondage...)
I confess that I don't understand why people act as though there's something mystical about printed circuit boards. Really. Go back and read what I've said. Admit it...it's 95% common sense. What? People need to have it pointed out that you should be able to read the part value? Hmmm...I already knew I was out of step with a large number of my fellow Americans, but...I mean...c'mon guys! Yet, people keep begging for The Secret To Making Printed Circuit Boards.
Uh, well, the secret is that you get a board, contrive a pattern on it, etch it, and you're done.
Okay, now that I've told you The Secret, I'm gonna have to shoot you.
Oh, I forgot the part where you pour something tasty at the end of the process. Lagavulin works for me. Or Highland Park. Or Talisker.
It's a little weird to me that people who do really random point-to-point with stuff squished into a space the size of a golf ball believe that the same components will suddenly burst into uncontrolled oscillation if placed on FR-4.
Sigh.
Grey
I think the idea of bending a lead 0.1" from the component is valid. I do this for the same reason you mention, but especially cause it looks so pretty.
But, because I grew up as a production finish carpenter paid by the opening, I look for ways to speed up the process--instead of using needle-nose pliers that force you to handle the component twice, I use a 20 watt, rectangular ceramic resistor as a jig. It has the correct bending width I require and allows me to simply bend my component's leads around it. The best part is that the ceramic device has a depression that allows the component, whose leads I'm bending, to rest in a pseudo saddle, thus leaving the leads exiting the component straight until they bend over the sides of the jig.
As far as keeping the values visible, I'm so anxious to listen to the prototype that I sometimes forget details like this. When this happens, the stuffing diagram is worth its weight in gold if I'm trouble shooting. Should I fabricate an amp for a friend, I'll certainly have to slow down and get the job done correctly.
BTW, with regards to pcb design, it's that last 5% that intrigues me.
But, because I grew up as a production finish carpenter paid by the opening, I look for ways to speed up the process--instead of using needle-nose pliers that force you to handle the component twice, I use a 20 watt, rectangular ceramic resistor as a jig. It has the correct bending width I require and allows me to simply bend my component's leads around it. The best part is that the ceramic device has a depression that allows the component, whose leads I'm bending, to rest in a pseudo saddle, thus leaving the leads exiting the component straight until they bend over the sides of the jig.
As far as keeping the values visible, I'm so anxious to listen to the prototype that I sometimes forget details like this. When this happens, the stuffing diagram is worth its weight in gold if I'm trouble shooting. Should I fabricate an amp for a friend, I'll certainly have to slow down and get the job done correctly.
BTW, with regards to pcb design, it's that last 5% that intrigues me.
My goodness! I've just read the entire thread! Took three days. I had been following it ages ago - and did get to re-read some - but decided to go from the start.Guess that means I'm enthused to build an Aleph-X.
Anyway, diving in.
Grey's monologue of PCBs hit a resonant note. It is astounding in so many DIY forums, not just this one, how often the entire thing seems to be a cheer squad to convince someone to put together a group buy, and then the cheer squad turns into a committee that seems intent on wrecking the PCB design. I spend a lot of time on a couple of guitar amp building forums. Anyone who proposes a PCB build of an amp is regarded as some sort of weirdo. Point to point or turret boards are the order of the day there. (Then again success is 100% THD and an amplifier that takes a relatively pure sine wave and turns it into something indistinguishable from a tungsten carbide tipped circular saw cutting sheet steel - including the volume level. Desirable sonic attributes include things like "crunch", grind" and "wail".)
A few thoughts however. PCB design isn't just about aesthetics - the thing really is a component of the design all of itself. Depending upon the nature of the device this is of greater or lesser import. Digital designs, and especially for audio: DAC construction, the success is probably more influenced by the PCB design than any other single component. Amplifiers sit somewhere in the middle. Any class B or AB design will be significantly influenced. Cherry pointed out the importance of circulating currents, and the dire effect of the switching transients in the power rails. Douglas Self pointed out that even a simple fraction of an inch of track in taking the feedback point off can lead to unexpected degradation of performance.
Luckily Nelson's designs are somewhat more immune from these issues. No switching transients, or indeed much in the way modulation of power rails. I do wonder if this benign nature might contribute a little to the success of the designs in the DIY community?
Even so - there are a lot of magnetic fields wandering about. Single ended amps seem to be more about steering current about than modulating the overall flow - but there will be asymmetries, and with some of the large currents about, possibly significant fields. So even here the rules apply. Keeping loop areas down, keeping cognisant that even a thick wire or track has some resistance and thus voltage drop, looking for the low Z loops - once the loop area is down look at the 3-D layout and think about the coupling with any other loops. Some matter.
Personally I am a little torn on building an Aleph-X. I had pretty much convinced myself to do a fully point to point build, and have some fun doing so. But the allure of a quick PCB build, where an evening's work would have the boards stuffed and likely working (as opposed to the inevitable mistake in the p2p build and the depressing task of removing the charred components and working out what I did wrong) is strong.
Anyway, if there really is a possibility of an update, I will sit back for a while. The winter is soon upon us here in Oz, and I do need something to entertain myself in the evenings.
carpenter said:
Considering our latest endavour (which is about to materialize as I write this), you should not have too many concerns about PCB layout 🙂
Neither should anybody else for that kind of matter!
I made my first PCB's freehand with an ecth resistant pen. It worked just fine. To do the toner transfer thing or to make photo boards is really no big deal! Anybody can do that with a maximum of 3 boards practice. (plenty of advice to be found on those topics here on this board).
If making some digital circuit layout things just might turn out a LITTLE more sensitive, but still no big deal for audio.
Really, just do it, it's not all that hard guys 🙂
Magura 🙂
Francis_Vaughan said:
It tickles me to watch people say they can't or won't or don't know how to do a circuit board...but lawsy-me, they sure do develop strong opinions when weighing in on someone else's layout!
Nelson has published several of his PCB layouts, but it's on a take it or leave it basis. You want some other pinout because you've got a pet part you want to use? Tough. Yes, I'm well aware of the difficulties getting the "right" parts--moreso than most posters. I just braved the Seven Rings of Hell to get my hands on some J271s, and the trials I went through for Toshiba JFETs are worthy of inclusion in classic Greek mythology. But...that still doesn't mean I'd botch up a perfectly good PCB layout just so it would accept any conceivable part available in some remote corner of the world.
If nothing else, I just flat-slap don't have the time to try to satisfy everyone.
Bummer, but there it is.
Grey
Way to go Magura! Hope the boards make some serious music.
I found this little pdf file; the author seems to know his subject matter:
🙂
Well, what do you know, the file's too large.🙁
It's located here: http://www.smps.us/pcb-design.html on the lower left hand side of the page. Title: PCB Design Tutorial
I found this little pdf file; the author seems to know his subject matter:
🙂
Well, what do you know, the file's too large.🙁
It's located here: http://www.smps.us/pcb-design.html on the lower left hand side of the page. Title: PCB Design Tutorial
Most of it seems oriented towards digital stuff.
Ground planes are good, but you're generally running into double-sided boards, which requires care to make sure things line up.
I confess that I'm glad to see a number of posts popping up here and there about circuit boards. Perhaps I've managed to raise awareness by fussing about it. I'm under no illusions, though. Two months from now, things will likely have settled back into the same comfortable rut.
Grey
Ground planes are good, but you're generally running into double-sided boards, which requires care to make sure things line up.
I confess that I'm glad to see a number of posts popping up here and there about circuit boards. Perhaps I've managed to raise awareness by fussing about it. I'm under no illusions, though. Two months from now, things will likely have settled back into the same comfortable rut.
Grey
GRollins said:
The facts of life. 😉
I, for one, have enjoyed our discussion--I've also learned plenty from Magura. My goal is to design boards to a higher standard.
🙂
GRollins said:
It's really also no big deal to line up a double sided board. Again, I'd say most people should be able to get it right in a few attempts. Nothing to worry about.
Magura 🙂
AP--
Scientists today released a new study indicating that the San Andreas fault will finally have its way with California's bottom. According to Dr. Size Moe Graf, the long-awaited split between the continental US and the lower left-hand portion of the nation will occur by this weekend. Asked about the upcoming split in an interview this afternoon, Mr. Andreas said, "It's not my fault!"
And in other news, a rather unwieldy thread started by a notorious tinkerer on the opposite coast of the US will finally hit .5M views.
Prominent religious figures interpret these signs as meaning that the end is nigh.
Grey
P.S.: My personal prediction is that central SC will suffer Death by Pollen if we don't get some rain soon. This is the earliest and the hardest I've seen the pollen hit...ever. At the rate things are going, it won't matter if the world does end this weekend. I won't be around to see it. It's like fog in my headlights at night when I'm driving home from work.
(No, I'm not allergic...just choking...)
Scientists today released a new study indicating that the San Andreas fault will finally have its way with California's bottom. According to Dr. Size Moe Graf, the long-awaited split between the continental US and the lower left-hand portion of the nation will occur by this weekend. Asked about the upcoming split in an interview this afternoon, Mr. Andreas said, "It's not my fault!"
And in other news, a rather unwieldy thread started by a notorious tinkerer on the opposite coast of the US will finally hit .5M views.
Prominent religious figures interpret these signs as meaning that the end is nigh.
Grey
P.S.: My personal prediction is that central SC will suffer Death by Pollen if we don't get some rain soon. This is the earliest and the hardest I've seen the pollen hit...ever. At the rate things are going, it won't matter if the world does end this weekend. I won't be around to see it. It's like fog in my headlights at night when I'm driving home from work.
(No, I'm not allergic...just choking...)
Hahah........
Sorry 'bout the pollen, Grey. But, think about this: we're approaching the big 500k. Your mother must be so proud; I know mine would.
🙂
Sorry 'bout the pollen, Grey. But, think about this: we're approaching the big 500k. Your mother must be so proud; I know mine would.
🙂
Mother's gone: Cancer. Father's gone: Cancer.
Actually, pretty much all of my family are gone.
None of them cared about electronics, anyway. Even my uncle, who did the radio electronics thing during WW II, didn't want to do it any more after the war. My father's idea of electronic repair was to change random tubes in the TV in hopes that it would stop the horizontal roll. Pretty sad, really, given that there was a tube diagram in the TV that clearly said which tube did what.
I decided to do things differently.
Grey
Actually, pretty much all of my family are gone.
None of them cared about electronics, anyway. Even my uncle, who did the radio electronics thing during WW II, didn't want to do it any more after the war. My father's idea of electronic repair was to change random tubes in the TV in hopes that it would stop the horizontal roll. Pretty sad, really, given that there was a tube diagram in the TV that clearly said which tube did what.
I decided to do things differently.
Grey
Off topic: Your mom may not reside here on Earth, but, assuming there's an afterlife, you can bet she's proud of her son--her husband, too. After all, at least he tried to correct the horizontal roll.
🙂
🙂
This does not necessarily fall into the category of what to do or not to do regarding circuit boards, but I find it useful in a lot of cases to break up the circuit into functional blocks. That way I can pull out a subassembly and do something else if I come up with a new idea; don't have to redesign the entire board.
No, I don't use edge connectors. If I did, I'd have to come up with some standardized pinout and there's no easy way to anticipate what you'll need. Imagine trying to adapt a pinout scheme for a standard push-pull amplifier to a circuit like an Aleph. You can't get there from here.
For example, when I was doing the New-Tron, I had scads of different ideas I wanted to try relating to the biasing--still haven't tried them all, in fact. I made a board with the basic Lovoltech/IRF cascode on it, then attached either circuit boards or circuits I whipped up on push blocks. It saved time, reduced wiring errors, and made things a lot more convenient.
Some circuits don't perform to my expectations. If I can't think of a way to make it work better, I'll usually melt it down for parts or junk it. I'm afraid I don't have Nelson's "Raiders of the Lost Ark" warehouse to keep things in. On the other hand, if the circuit has utility, I'll keep it around. I've got MOSFET current sources with the pass devices already mounted on heatsinks, for instance. That's a really useful thing to have around. Change one resistor to program the current and you're ready to go.
No, I don't make circuit boards for everything. I usually start by cobbling together something on a push block. If it works okay, I'll start adding things. As it grows, and if it's performing decently, I may move some of the subcircuits off onto circuit boards...assuming that I can spare the time to work up a board.
The Aleph-X is the most complicated circuit I've done entirely on push blocks. By the time I got the thing locked in, I was pushing the limit for how many parts I could squeeze into such a limited space. I don't want to go that far again. It was a pain in the rump.
I remember being at Lou Johnson's (of Conrad Johnson) house and seeing a prototype amp on the floor in his listening room. He was using the chassis, power supply, and output stage of an MV-75 (at that time current product for them), but there was a perfboard on standoffs where the front end would normally be. Neat idea, but I don't have a "production" circuit that I can use as a guinea pig for further development, since most everything I do is a one-off, but it sure speeds things up when you can use large portions of another circuit as a springboard for further tinkering.
Later this year, I hope to have some things like that nailed down. If it happens, I'll try to post new circuits more often.
Grey
No, I don't use edge connectors. If I did, I'd have to come up with some standardized pinout and there's no easy way to anticipate what you'll need. Imagine trying to adapt a pinout scheme for a standard push-pull amplifier to a circuit like an Aleph. You can't get there from here.
For example, when I was doing the New-Tron, I had scads of different ideas I wanted to try relating to the biasing--still haven't tried them all, in fact. I made a board with the basic Lovoltech/IRF cascode on it, then attached either circuit boards or circuits I whipped up on push blocks. It saved time, reduced wiring errors, and made things a lot more convenient.
Some circuits don't perform to my expectations. If I can't think of a way to make it work better, I'll usually melt it down for parts or junk it. I'm afraid I don't have Nelson's "Raiders of the Lost Ark" warehouse to keep things in. On the other hand, if the circuit has utility, I'll keep it around. I've got MOSFET current sources with the pass devices already mounted on heatsinks, for instance. That's a really useful thing to have around. Change one resistor to program the current and you're ready to go.
No, I don't make circuit boards for everything. I usually start by cobbling together something on a push block. If it works okay, I'll start adding things. As it grows, and if it's performing decently, I may move some of the subcircuits off onto circuit boards...assuming that I can spare the time to work up a board.
The Aleph-X is the most complicated circuit I've done entirely on push blocks. By the time I got the thing locked in, I was pushing the limit for how many parts I could squeeze into such a limited space. I don't want to go that far again. It was a pain in the rump.
I remember being at Lou Johnson's (of Conrad Johnson) house and seeing a prototype amp on the floor in his listening room. He was using the chassis, power supply, and output stage of an MV-75 (at that time current product for them), but there was a perfboard on standoffs where the front end would normally be. Neat idea, but I don't have a "production" circuit that I can use as a guinea pig for further development, since most everything I do is a one-off, but it sure speeds things up when you can use large portions of another circuit as a springboard for further tinkering.
Later this year, I hope to have some things like that nailed down. If it happens, I'll try to post new circuits more often.
Grey
First my congratulations on the progress toward 500 kiloposts!
I'm sure this subject was beaten to death in a previous thread that I can't find, but in the interest of expediting my education, I'll risk asking anyway. Please rest assured that I've been through the thread many times looking for this info and just didn't find it.
What is the purpose of Q4, R10 and R13 in Grey's original ckt (see Post 1 in the thread)?
I just completed a set of Aleph 30s, and they also appear to have this circuitry in place (called Q4, R15 and R16 in Nelson's A30 service manual schematic). Unfortunately it's not in the simplified schematic for the A30, or mentioned in the service manual.
My thought is that it looks kinda like the CCS present in some of Nelson's earlier Zen projects, but the diff pair already appears to have an adjustable CCS (Q6, D1, R17, R24, R26, V2), and the output transistors (Q2) already has the Aleph CS as its variable current source. Is this a second CCS at the bottom of the diff pair, intended to regulate current through Q7?
Thanks,
Bryan A. Thompson
bryan@batee.com
I'm sure this subject was beaten to death in a previous thread that I can't find, but in the interest of expediting my education, I'll risk asking anyway. Please rest assured that I've been through the thread many times looking for this info and just didn't find it.
What is the purpose of Q4, R10 and R13 in Grey's original ckt (see Post 1 in the thread)?
I just completed a set of Aleph 30s, and they also appear to have this circuitry in place (called Q4, R15 and R16 in Nelson's A30 service manual schematic). Unfortunately it's not in the simplified schematic for the A30, or mentioned in the service manual.
My thought is that it looks kinda like the CCS present in some of Nelson's earlier Zen projects, but the diff pair already appears to have an adjustable CCS (Q6, D1, R17, R24, R26, V2), and the output transistors (Q2) already has the Aleph CS as its variable current source. Is this a second CCS at the bottom of the diff pair, intended to regulate current through Q7?
Thanks,
Bryan A. Thompson
bryan@batee.com
batee,
Here is a link to the parts#'s and their function.
http://www.diyaudio.com/forums/showthread.php?postid=113645#post113645
The two transistor circuits (Q4, Q9) can be left out completely as it comes to the basic functions of the amplifier.
Hope this helps.
Edit: scroll down to post# 1778.
/Hugo
Here is a link to the parts#'s and their function.
http://www.diyaudio.com/forums/showthread.php?postid=113645#post113645
The two transistor circuits (Q4, Q9) can be left out completely as it comes to the basic functions of the amplifier.
Hope this helps.
Edit: scroll down to post# 1778.
/Hugo
Thanks. I now understand that this is an overcurrent protection circuit.
It appears that the base of Q4 is looking at the voltage dropped by R6 (the .22 Ohm source resistor for Q2).
My guess is that when that voltage hits ~.65V, the transistor starts to conduct and lowers the gate voltage of by pulling the gate of Q2 toward ground through Q4. That part makes sense.
I'm still trying to figure out the role of R13. I guess together with R10 it forms a voltage divider and sends about 30% of the voltage that appears across R6 to the base of Q4. To cause that transistor to conduct, we need about .65V. That means 2.15V across R6, or a Q2 Idmax of 9.777A. Does this seem right?
One more question:
I've seen posts from Nelson, Grey et al that say this is overcurrent protection and that it isn't necessary if a short to ground (I assume of the speaker outputs) can be guaranteed. Since the topside power FET Q1 is protected by the Aleph current source, that the Q4 protection circuit is only there to protect Q2?
Bryan
It appears that the base of Q4 is looking at the voltage dropped by R6 (the .22 Ohm source resistor for Q2).
My guess is that when that voltage hits ~.65V, the transistor starts to conduct and lowers the gate voltage of by pulling the gate of Q2 toward ground through Q4. That part makes sense.
I'm still trying to figure out the role of R13. I guess together with R10 it forms a voltage divider and sends about 30% of the voltage that appears across R6 to the base of Q4. To cause that transistor to conduct, we need about .65V. That means 2.15V across R6, or a Q2 Idmax of 9.777A. Does this seem right?
One more question:
I've seen posts from Nelson, Grey et al that say this is overcurrent protection and that it isn't necessary if a short to ground (I assume of the speaker outputs) can be guaranteed. Since the topside power FET Q1 is protected by the Aleph current source, that the Q4 protection circuit is only there to protect Q2?
Bryan