| Bricolo |
6mm aluminium, 430x280x75mm
Here are a few pictures: |
|
|
| Bricolo |
I'll let the plastic sheets over the plates until the chassis is completely finished. This will avoid scraches when I'll work on it.
Any comments? |
|
|
| millwood |
| quote: | Originally posted by Bricolo
Any comments? |
she is a beauty.
where did you get the aluminum plates and how did you work on them? |
|
|
| Bricolo |
I bought the plates from a company that works with aluminium, near strasbourg
I drilled the holes with a (don't know if it's the correct word in english) stand-driller (a big driller on a stand). Holes are 5mm, with a chamfering for the screws
the "inner holes" were drilled with 4.2mm and then I made a M5 tapping |
|
|
| Bricolo |
now I'm wondering how I'm going to place all my gainclone's components in it :scratch:
should I place the toroid in the center, ant then each channel at one side?
or place the toroid in an edge or a side? |
|
|
| Peter Daniel |
| I would place it in a center. |
|
|
| Rarkov |
As I have just written on another thread...
Absolutley stunning! People are actually catching up with PD's standards! (I'm just trying to nudge him into doing something outstanding! ;))
Keep up the great work and pictures. The name for the drill you were using is called a Pillar Drill.
Gaz |
|
|
| Bricolo |
| quote: | Originally posted by Peter Daniel
I would place it in a center. |
OK :)
Peter, any comments about my case? I know I'm still far from your artwork skills, but I'd like to know what you think about my first chassis.
The problem I've got with it (the only one for now):
the top (and bottom) plates are "inside" the others, not other and under. I did it because of aesthetics, this way when you look at the amp (in front of it) you only see the front plate, ant not the front plate with the left/right/top/bottom plates all around of it.
but I have difficulties to put the top plate off, it's strongly hol in place by the other plates when they are screwed |
|
|
| ScottRHinson |
| quote: | Originally posted by Bricolo
now I'm wondering how I'm going to place all my gainclone's components in it :scratch:
should I place the toroid in the center, ant then each channel at one side?
or place the toroid in an edge or a side? |
Placing it in the center leads to a very balanced amplifier weight wise. But unless you plan on moving it a lot...this isn't all that critical. Lots of amplifiers do this, but they usually have heatsinks for each channel on either side of the amp. So this layout makes sense for them.
However, I would place it on one side, bringing the AC into the chassis on that same side. Signal in would come in on the far opposite side, to minimize noise. Loudspeaker out would come out of the chassis nearer the signal in than the AC in. This keeps your AC as far away as possible. In fact I have seen, and have made designs where an aluminum/steel divider is placed between the transformer/rectifiers and bulk capacitance and the signal portions of the design. This creates a Faraday cage around the noisy parts.
Toroids can and do leak EM noise, especially around the input/output wiring.
Scott |
|
|
| Peter Daniel |
Very nicely done and there is not much to improve here. If the top panel is too tight, you might try to trim it a bit, with belt sander (if available).
This chassis style is very similar to what PassLabs use, the only exception is that top panel is placed over the rear panel and this helps to open the cover (and provides some extra rigidity) |
|
|
| millwood |
| I would place the transformer on the far back (either left or right depending on where your power line comes in). |
|
|
| Bricolo |
| quote: | Originally posted by Rarkov
As I have just written on another thread...
Absolutley stunning! People are actually catching up with PD's standards! (I'm just trying to nudge him into doing something outstanding! ;))
Keep up the great work and pictures. The name for the drill you were using is called a Pillar Drill.
Gaz |
Thanks, Gaz
Teach me some english, please :) Online translators don't work for those technical words
what's the name for all those tools? |
|
|
| Peter Daniel |
| quote: | Originally posted by millwood
I would place the transformer on the far back (either left or right depending on where your power line comes in). |
You are not saying that because of my suggestion to place it in a center?
My reasoning to put it centrally is following. This is quite a big chassis by GC standards. If this is stereo amp, you should definitely use dual mono layout, with ea channel on either side and probably using side panels for heatsinking. This leaves the center space empty and it's a perfect place to mount transformer, or maybe even two. Also AC input should be placed centrally and both RCA jacks and binding posts separate on both ends of rear panel. Placing transformer centrally makes for better balanced chassis as well, not to mention having the same resonances for both channels;) |
|
|
| Bricolo |
| quote: | Originally posted by Peter Daniel
Very nicely done and there is not much to improve here. If the top panel is too tight, you might try to trim it a bit, with belt sander (if available).
This chassis style is very similar to what PassLabs use, the only exception is that top panel is placed over the rear panel and this helps to open the cover (and provides some extra rigidity) |
You're the man, Peter!
I didn't think about this solution. It's too late now, but I keep it in mind for the next time.
BTW, how is this pass chassis done for the bottom? The same as for the top? layong over the back plate? |
|
|
| Sparhawk |
| quote: | Originally posted by Rarkov
The name for the drill you were using is called a Pillar Drill. |
Here, we would call it a drill press. :nod: |
|
|
| Peter Daniel |
| Here's the rear view. That's a very clever and efficient way to built a chassis (if you don't mind using 1/4" panels, of course;)) |
|
|
| Bricolo |
Well, I was hesitating between 2 "layouts", and 50% tell me to use the 1st, and the other 50% tell me to use the 2nd
Next time I'll throw 1€ and look if it falls on the top or on the bottom, instead of asking a question here ;) |
|
|
| Bricolo |
| quote: | Originally posted by Peter Daniel
Here's the rear view. That's a very clever and efficient way to built a chassis (if you don't mind using 1/4" panels, of course;)) |
Thanks!
Mine is built the same on the rear as on the front, the pass one is far better
is there any advantage in having an offseted rear pannel? |
|
|
| ScottRHinson |
| quote: | Originally posted by Peter Daniel
You are not saying that because of my suggestion to place it in a center?
My reasoning to put it centrally is following. This is quite a big chassis by GC standards. If this is stereo amp, you should definitely use dual mono layout, with ea channel on either side and probably using side panels for heatsinking. This leaves the center space empty and it's a perfect place to mount transformer, or maybe even two. Also AC input should be placed centrally and both RCA jacks and binding posts separate on both ends of rear panel. Placing transformer centrally makes for better balanced chassis as well, not to mention having the same resonances for both channels;) |
I'm sorry Peter, but I disagree. The cheapest way to reduce noise in an electrical system is distance...pure and simple. The best way is a well thought out grounding system and Faraday cages around the noisy and quiet parts to separate them.
I assume EMI is what you mean by the term resonance?
I have never liked a dual mono layout because it becomes much easier to make a mistake in running signals near power lines, either the full wave primary or rectified secondary lines. Those secondary currents can get all over the place if your not careful and easily set the noise and distortion floor for the amplifer.
Can it be done well? Yes. Is it much harder. Yup. If I were the builder of this amp, I'd get a big piece of aluminum bar stock and wedge it into one side of the amp. If it were the right size it could tie the side to the top and bottom thermally and even the front and back. I'd mount the gainclone chips to that, and you have a huge thermal mass to cool the chips. You can keep the chips as far away from those nasty power supply lines and realize the lowest noise floor, quietest amp you can.
Scott |
|
|
| Peter Daniel |
| This will work too. I guess it's a matter of preference. With a big chassis like that you can use almost any layout. I just like symmetry and separation between channels. |
|
|
| Bricolo |
The 1st solution has the transformer on the side
advantages:
less EMI from the transformer
disadvantages:
I can't use a long axis for the volume pot
the 2nd has the transformer on the middle:
advantages:
I can use a long axis
disadvantage:
EMI
In both cases, I can place metal plates around the transformer
but it I do this, in the 2nd case, the AC inlet wires aren't in this small housing |
|
|
| Bricolo |
2nd one:
note that with the 2nd option, I can use both sides as a heatsinks (maybe this isn't critical with a gainclone) |
|
|
| ScottRHinson |
| quote: | Originally posted by Bricolo
The 1st solution has the transformer on the side
advantages:
less EMI from the transformer
disadvantages:
I can't use a long axis for the volume pot
the 2nd has the transformer on the middle:
advantages:
I can use a long axis
disadvantage:
EMI
In both cases, I can place metal plates around the transformer
but it I do this, in the 2nd case, the AC inlet wires aren't in this small housing |
I see that you've got dual potentiometers for volume control. I'm going to modify/clarify some of my advice. Bring the power wiring straight forward from the transformer on the right side. Run it side to side along the very front of the chassis, then back to the GC amps on the left side along the left side.
Now take the speaker output straight back and exit the far corner (this is different than I said before, now that I see the layout this makes more sense). Bring the signal lines in next to the speaker out and keep them as short as possible. I'm guessing you want to have a symmetrical front panel? If you're not attached to it, put both pots on the left 1/3 of the chassis, it will still look pretty classy and you'll be able to keep the signal wiring perpendicular, or orthagonal (spelling?) to the power lines as much as you can. Make sense?
Scott |
|
|
| Bricolo |
| quote: | Originally posted by ScottRHinson
I see that you've got dual potentiometers for volume control. I'm going to modify/clarify some of my advice. Bring the power wiring straight forward from the transformer on the right side. Run it side to side along the very front of the chassis, then back to the GC amps on the left side along the left side.
Now take the speaker output straight back and exit the far corner (this is different than I said before, now that I see the layout this makes more sense). Bring the signal lines in next to the speaker out and keep them as short as possible. I'm guessing you want to have a symmetrical front panel? If you're not attached to it, put both pots on the left 1/3 of the chassis, it will still look pretty classy and you'll be able to keep the signal wiring perpendicular, or orthagonal (spelling?) to the power lines as much as you can. Make sense?
Scott |
Yes, I want a symmetrical front pannel |
|
|
| Bricolo |
That's the layout I was also thinking about
But where is the AC inlet? |
|
|
| Peter Daniel |
| quote: | Originally posted by Bricolo
But where is the AC inlet? |
It is probably coming through the bottom, directly to the transformer. |
|
|
| Peter Daniel |
| I wouldn't recommend dual volume pots as it's very inconvenient to adjust volume. Why not a single pot? |
|
|
| Bricolo |
With an input selector and a dual pot, I have 2 buttons on the faceplate
This not only look nicer, but with a 3rd one I could never use long axes for the 3 ones. |
|
|
| ScottRHinson |
| quote: | Originally posted by Bricolo
That's the layout I was also thinking about
But where is the AC inlet? |
I was wondering the same thing, I don't see it. If it's under the PCB in the center, and the PCB has a good ground plane there shouldn't be much of a noise issue, and it looks to be a good implementation of that layout.
Scott |
|
|
| Bricolo |
If I use a shielded AC cable from the inlet to the transformer, will it cancel 100% of the EMI?
If it's good, I could place the transformer and bridges at the center, in a little metal enclosure, and the ac inlet to the right (since the RCA inputs are in the center) connected to the transformer with a shielded cable |
|
|
| Bricolo |
| quote: | Originally posted by ScottRHinson
I was wondering the same thing, I don't see it. If it's under the PCB in the center, and the PCB has a good ground plane there shouldn't be much of a noise issue, and it looks to be a good implementation of that layout.
Scott |
Yes, the layout seems very good!
I'd like to build my GC like this amp.
The the only problem is: the AC inlet.
I don't have enough vertical speace to place 2 rows of RCA and an AC inlet :( |
|
|
| Peter Daniel |
| quote: | Originally posted by Bricolo
With an input selector and a dual pot, I have 2 buttons on the faceplate
This not only look nicer, but with a 3rd one I could never use long axes for the 3 ones. |
My mistake then, I thought you wanted to use separate pots for left and right channel, but I guess I got biased by the other post. |
|
|
| Peter Daniel |
| quote: | Originally posted by Bricolo
Yes, the layout seems very good!
I'd like to build my GC like this amp.
The the only problem is: the AC inlet.
I don't have enough vertical speace to place 2 rows of RCA and an AC inlet :( |
It's not recommended to place RCA and AC connection close together. Why not do it through the bottom panel and use 90 deg offset connector for AC line? |
|
|
| Bricolo |
| quote: | Originally posted by Peter Daniel
My mistake then, I thought you wanted to use separate pots for left and right channel, but I guess I got biased by the other post. |
Look at my 2 ugly drawings
2 pots, with one of them having much more cables connected to it
don't one look like an input selector, and the other like a volume pot? ;) |
|
|
| Bricolo |
| quote: | Originally posted by Peter Daniel
It's not recommended to place RCA and AC connection close together. Why not do it through the bottom panel and use 90 deg offset connector for AC line? |
Humm... I'd like little feets, so... no
But what about placing the AC connection at one side, and connect it to the Xformer with a shielded cable? |
|
|
| ScottRHinson |
| quote: | Originally posted by Bricolo
If I use a shielded AC cable from the inlet to the transformer, will it cancel 100% of the EMI?
If it's good, I could place the transformer and bridges at the center, in a little metal enclosure, and the ac inlet to the right (since the RCA inputs are in the center) connected to the transformer with a shielded cable |
That could very well work. Shielded cables have to be used with caution, as does all grounding. One of the better articles I've seen on the subject is here:
http://www.analog.com/UploadedFiles...76254AN-347.pdf
Take a look at that.
I would recommend a sub enclosure for your transformer for sure. Be VERY careful not to create a shorted turn, or a metal loop all the way around the toroid in this case.
Scott |
|
|
| millwood |
| quote: | Originally posted by Peter Daniel
You are not saying that because of my suggestion to place it in a center? |
you think too highly of yourself, Peter.
I think A/C noise is tough to get rid of. If I put the transformer close to the a/c in, I can significant shorten stray a/c wires and don't have to worry much about shielding the chips/wires.
I also think the idea of placing the toroid centrally and wire the a/c in from the bottom of the amp is quite good a suggestion. It shortens a/c wire length and provides much better balance at the same time. and it is quite unique.
As to the feet: Home Depot sells machined metal knobs for cabinet and they make good feet for an amp.
My local cabinet install can also get marble feet as well. That would be cool. |
|
|
| Rarkov |
Here we go then...
1) These are Taps (the opposite are called Dies)
2) Center punch
3) Wish I knew...What's it's function?
4) Reamer
5) Counter Sinker
Again - Amazing work!
Gaz |
|
|
| Bricolo |
| quote: | Originally posted by Rarkov
Here we go then...
1) These are Taps (the opposite are called Dies)
2) Center punch
3) Wish I knew...What's it's function?
4) Reamer
5) Counter Sinker
Again - Amazing work!
Gaz |
the word to word translation would be "centering drill"
this tool is usefull when your 5mm (or 10mm or what you want) drill is too inacurate to drill in the small hole you did with the center punch
so, you make a little hole with this tool, and then, you can easilly adjust the big drill in the big hole :)
PS: I don't know if drill is the correct word, my translator told me this. A drill is the helicoidal tool you use to drill holes |
|
|
| Bricolo |
| quote: | Originally posted by millwood
you think too highly of yourself, Peter.
I think A/C noise is tough to get rid of. If I put the transformer close to the a/c in, I can significant shorten stray a/c wires and don't have to worry much about shielding the chips/wires.
I also think the idea of placing the toroid centrally and wire the a/c in from the bottom of the amp is quite good a suggestion. It shortens a/c wire length and provides much better balance at the same time. and it is quite unique.
As to the feet: Home Depot sells machined metal knobs for cabinet and they make good feet for an amp.
My local cabinet install can also get marble feet as well. That would be cool. |
since you're talking about placing the AC inlet close to the Xformer
If it's close enough, I won't use shielded cable, but the Xformer's primary cable themselves.
Can I add a shield to this pair of cables? With an aluminium sheet, or by using a cat5 cable's shield? |
|
|
| ScottRHinson |
| quote: | Originally posted by Bricolo
since you're talking about placing the AC inlet close to the Xformer
If it's close enough, I won't use shielded cable, but the Xformer's primary cable themselves.
Can I add a shield to this pair of cables? With an aluminium sheet, or by using a cat5 cable's shield? |
If you've got an aluminum shield around that section you won't need to shield the wires too. When you run the DC wires out of that section wrap +/-/gnd tightly with each other, "braid" if you will. That will keep those sections mostly under control.
Scott |
|
|
| breguetphile |
... to post my new case!!
i didn't wanna waste a thread on this, so this looks like a great place to sneak in a pic of mine. sorry the picture isn't that great. hard to get much better with the black. |
|
|
| Bricolo |
No, the cables from the transformer to the ac inlet won't ben in the "PS shielded section"
Look at the link Peter Daniel gave, I want to do the same thing, but since I can't put the AC inlet at the bottom, I'll place it on the rear right. So, the AC inlet won't be in the shielded section |
|
|
| Sandy H. |
Centering drill or Center drill is a common name here in the US. The tool, while convenient for creating a pilot hole for larger drills, or even small drills to keep them from walking around, takes its dimensions from its use in the tailstock of lathes. One would put a piece of bar in the jaws (or other work holding piece) of the headstock of a lathe and the center drill in the tailstock. Fire the machine up and use the tailstock to push the stationary center drill into the rotating bar, creating a small hole with a specific chamfer at the center of the bar. Remove the center drill and replace it with a live or dead center in the tailstock to steady the work from that end. It is practically mandatory for many lathe operations.
Attached is a pic showing the center drilling operation (bar rotating, drill stationary in tailstock), the resulting hole/chamfer and a diagram of a live center, which will fit in the chamfer left by the centering drill. Now that you see the application, think of how many items you have seen with that little chamfered hole at the center. . .
Sandy. |
|
|
| Bricolo |
| quote: | Originally posted by Sandy H.
Centering drill or Center drill is a common name here in the US. The tool, while convenient for creating a pilot hole for larger drills, or even small drills to keep them from walking around, takes its dimensions from its use in the tailstock of lathes. One would put a piece of bar in the jaws (or other work holding piece) of the headstock of a lathe and the center drill in the tailstock. Fire the machine up and use the tailstock to push the stationary center drill into the rotating bar, creating a small hole with a specific chamfer at the center of the bar. Remove the center drill and replace it with a live or dead center in the tailstock to steady the work from that end. It is practically mandatory for many lathe operations.
Attached is a pic showing the center drilling operation (bar rotating, drill stationary in tailstock), the resulting hole/chamfer and a diagram of a live center, which will fit in the chamfer left by the centering drill. Now that you see the application, think of how many items you have seen with that little chamfered hole at the center. . .
Sandy. |
Very clear explanation! Thanks!
I tried to put my aluminium plates in a lathe, to make this little chamfer, I don't know why but it didn't work :D
I used the centering drill with the press drill instead |
|
|
| tbla |
btw peter and everyone else, did you notice the big black caps in the brinkmann.....epcos sikorel, any experience with those...?
:cheerful: |
|
|
| ScottRHinson |
| quote: | Originally posted by Bricolo
No, the cables from the transformer to the ac inlet won't ben in the "PS shielded section"
Look at the link Peter Daniel gave, I want to do the same thing, but since I can't put the AC inlet at the bottom, I'll place it on the rear right. So, the AC inlet won't be in the shielded section |
I got it. You can either shield the cable, or run all signal wires at right angles to the AC cable when you have to take it past it. That will minimize cross talk. The AC cable itself isn't quite as bad of a problem as the DC lines which carry the half wave rectified currents related to the signal.
Scott |
|
|
| Bricolo |
| quote: | Originally posted by ScottRHinson
That could very well work. Shielded cables have to be used with caution, as does all grounding. One of the better articles I've seen on the subject is here:
http://www.analog.com/UploadedFiles...76254AN-347.pdf
Take a look at that.
I would recommend a sub enclosure for your transformer for sure. Be VERY careful not to create a shorted turn, or a metal loop all the way around the toroid in this case.
Scott |
Very nice application note :nod:
But after having read this (everyone should read this!), I'm not so sure about the efficiency of a metal separation between the amp ant the psu, since metal is so unefficient to stop magnetic fields |
|
|
| Bricolo |
I feel sooo stupid since Peter showed me the pictures of the Pass preamp. Why haven't I put the top and bottom plates over the rear one? :bawling:
Now I can't change anything anymore, and I'm stuck with this top plate that is hard to remove.
But I found an easy solution to remove it without having to unscrew all the other sides:
:D |
|
|
| Da5id4Vz |
You could attach an air chuck to the rear panel and use compressed air to pop the top off.
More praticle could be a pair of finger holes in the corners. The plate also sounds thick enough to tap one or more holes that could be used to scew in some sort of handle when you need to open it.
More practical could be a pair of finger holes in the corners. The plate also sounds thick enough to tap one or more holes that could be used to screw in some sort of handle when you need to open it.
An extreme solution would be to hinge one end and have dampers that would open the lid from inside when two screws are removed. In a similar fashion, a linear actuator could open the lid from a front panel control.
There are no problems, just bad suggestions from other people. |
|
|
| ScottRHinson |
| quote: | Originally posted by Bricolo
Very nice application note :nod:
But after having read this (everyone should read this!), I'm not so sure about the efficiency of a metal separation between the amp ant the psu, since metal is so unefficient to stop magnetic fields |
It's not the magnetic field I would worry about with a toroidal transformer. They are inherently very low magnetic field devices because of their very construction. This is not true for other types of transformers.
It's the electric fields that could cause an issue, and this is true with any transformer. You've got to get the wires in and out somehow.
I've heard of more than one commercial mfg that allows for the transformer to be rotated before it is bolted down to make sure they have the minimum noise possible.
I've attached a pic of a well regarded, well measuring, $300 integrated amp. I've airbrushed out the name of the company, which was on the transformer. There is a metal sheet that runs most of the way down the side between the transformer and the signal circuitry. This piece does not provide any kind of mechanical support, the way it's mounted isn't strong enough to do that. It's not a complete Faraday cage around the transformer but they must have done tests and this fixed some sort of problem. Notice that the transformer leads come out on the far side of the signal circuitry. This isn't on accident either I bet.
On the transformer is printed:
Custom Designed Audio Grade Transformer
Excellent Distortion Characteristics
Ultra Low Magnetic Fields
High Efficiency Low Loss
I hope this helps...
Scott |
|
|
| Peter Daniel |
| This is what I did in my preamp to isolate transformers. I've built a cage out of 1/8" copper plates and filled the space with epoxy. The AC connection is also done here on the bottom panel, right beside the transformer's housing. |
|
|
| Sandy H. |
Isn't lead good for EMF shielding? I remember from the dirt track racing days of long ago that bath tub liners were 1/8"-ish lead bases which were cheap sources for lead for melting ballast. If lead is a good EMF shield, wouldn't this be a good source for the DIY guy? Am I off base? I imagine that there are other good sources for small sheets of thin lead as well.
Let me know, as I think this could be pertinant to me for future projects.
Sandy. |
|
|
| Bricolo |
| quote: | Originally posted by Peter Daniel
This is what I did in my preamp to isolate transformers. I've built a cage out of 1/8" copper plates and filled the space with epoxy. The AC connection is also done here on the bottom panel, right beside the transformer's housing. |
won't the transformer heat with this?
Sandy: I don't know about the EMI shielding capacity of lead, but it's a good nuclear shield, so there's no reason that it wouldn't also be a bood EMI shield
But lead is something that people seem to avoid (I think it's bad for health), so I think I'ill use steel (after having read ScottRHinson's link) |
|
|
| Bricolo |
Some questions about the last 2 pictures:
ScottRHinson: what's at the right of the transformer, in this amp?
Does someone have an idea why the shielding plates don't go completely from one side to the other?
Peter Daniel: how did you fix the metal spacers that are between the PCBs and the chassis plates? Are they screwed? How did you do that? (I can't see how you can drill a hole and taper in in a such thin plate) |
|
|
| jh6you |
| quote: | Originally posted by Bricolo
Now I can't change anything anymore, and I'm stuck with this top plate that is hard to remove.
|
I recommend no top plate as I remember from the forum that the open top gives better sound. The open top is also good in cooling amp. I believe it is OK for you as I suppose you have no child yet.
:yinyang: |
|
|
| Bricolo |
| quote: | Originally posted by ScottRHinson
I would recommend a sub enclosure for your transformer for sure. Be VERY careful not to create a shorted turn, or a metal loop all the way around the toroid in this case.
Scott |
Can you explain why? I was thinking about making a faraday cage around the PS, but this makes a sort of shorted turn. What's the problem with this?
jh6you: I prefer a closed top, because of the dust. And yes, my sister has childs that are often here, so...
But I was thinking about placing a little sheet of damping material (very thin, lake a paper sheet) between all the places where 2 plates touch, this would damp the chassis vivrations
Good idea? |
|
|
| ScottRHinson |
| quote: | Originally posted by Bricolo
Some questions about the last 2 pictures:
ScottRHinson: what's at the right of the transformer, in this amp?
Does someone have an idea why the shielding plates don't go completely from one side to the other?
|
Everything is to the right of the transformer. Signal stages, power amp, volume controls everything. I know exactly why it doesn't run the full length. Even if you dont' completely shield something a well placed partial shield can do most if not the whole job. I've done this with RF circuits on several occasions. I had sophisticated gear to tell me how I was doing with placement though. That amount of shielding was deemed good enough, so that's why it stops where it does.
Scott |
|
|
| ScottRHinson |
| quote: | Originally posted by Bricolo
Can you explain why? I was thinking about making a faraday cage around the PS, but this makes a sort of shorted turn. What's the problem with this?
|
Not quite. A shorted turn is a conductive path through the center of the toroidal transformer, around the outside, and then back to the center. If you can start at a point, say the mounting bolt, and you attach that bolt to the bottom of the chassis, AND the top of the chassis then you can draw a complete circle through the center of the transformer and it's a shorted turn. This is just like taking your outputs, shorting them together and then plugging them in. Transformer death is the result.
If you only attach the bolt to the bottom of the chassis and not the top, there is not complete circle through the transformer. No shorted turn.
Scott |
|
|
| Bricolo |
| quote: | Originally posted by ScottRHinson
Everything is to the right of the transformer. Signal stages, power amp, volume controls everything. I know exactly why it doesn't run the full length. Even if you dont' completely shield something a well placed partial shield can do most if not the whole job. I've done this with RF circuits on several occasions. I had sophisticated gear to tell me how I was doing with placement though. That amount of shielding was deemed good enough, so that's why it stops where it does.
Scott |
OK, but is there a problem in using the full length? |
|
|
| ScottRHinson |
| quote: | Originally posted by Bricolo
OK, but is there a problem in using the full length? |
nope, you don't need to guess on if you have enough the. It'll be enough, because it's all you can do.
Scott |
|
|
| Bricolo |
| quote: | Originally posted by ScottRHinson
Not quite. A shorted turn is a conductive path through the center of the toroidal transformer, around the outside, and then back to the center. If you can start at a point, say the mounting bolt, and you attach that bolt to the bottom of the chassis, AND the top of the chassis then you can draw a complete circle through the center of the transformer and it's a shorted turn. This is just like taking your outputs, shorting them together and then plugging them in. Transformer death is the result.
If you only attach the bolt to the bottom of the chassis and not the top, there is not complete circle through the transformer. No shorted turn.
Scott |
OK, I understant.
There won't be a shorted turn going thru the center of the transformer, it's only bolted to the bottom of the chassis (but the top of the screw will be very close to the top plate)
PS: how can you see that a transformer is dead or damaged? |
|
|
| fedde |
You can smell it... :devilr:
Fedde |
|
|
| Bricolo |
| quote: | Originally posted by fedde
You can smell it... :devilr:
Fedde |
:D
I asked this question because at the beginning of my gainclone project, I wired a PS cap in the wrong polarity
->BAM!
the cap "exploded", and the tiny cables it was soldered to had theyr insulation melted
my big mistake was that I didn't use a fuse on the mains. So, big currents can have flown thru the transformer, and I don't know if it's damaged (the amp still works now, after having changed the cap) |
|
|
| fedde |
Never omit a fuse at the primaries of the toroids! In case of a short you risk fire in the toroids or melting of the internal fuse of the toroid. :hot:
I don't think the toroid is damaged by the cap. You could measure the impedances of the primaries and secondaries. (and compare the measurements to your second toroid, if you have that...)
Fedde |
|
|
| Peter Daniel |
| quote: | Originally posted by Bricolo
Peter Daniel: how did you fix the metal spacers that are between the PCBs and the chassis plates? Are they screwed? How did you do that? (I can't see how you can drill a hole and taper in in a such thin plate) |
I used metal stand offs. They have screw end on one side (which goes into bottom panel) and the hole on top, where PCB mounting screw is. |
|
|
| Bricolo |
| quote: | Originally posted by fedde
Never omit a fuse at the primaries of the toroids! In case of a short you risk fire in the toroids or melting of the internal fuse of the toroid. :hot:
I don't think the toroid is damaged by the cap. You could measure the impedances of the primaries and secondaries. (and compare the measurements to your second toroid, if you have that...)
Fedde |
Yes I know, now I always use a fuse
BTW, what are you meaning in "the internal fuse of the toroid"?
Peter: I see how the stand off are made, but what I want to know is how the bottom panel is done.
Have you drilled a hole and tapered it, so you can screw the stand off in it? If yes, did you drill a complete hole in the bottom panel (I mean a hole that goes to the exterior) |
|
|
| Peter Daniel |
| quote: | Originally posted by Bricolo
Peter: I see how the stand off are made, but what I want to know is how the bottom panel is done.
Have you drilled a hole and tapered it, so you can screw the stand off in it? If yes, did you drill a complete hole in the bottom panel (I mean a hole that goes to the exterior) |
That's exactly what I did. It's drilled through, but since it's the bottom, I don't see it and it doesn't bother me. It also provides more "industrial" feel to the whole chassis;) |
|
|
| Bricolo |
| quote: | Originally posted by Peter Daniel
It also provides more "industrial" feel to the whole chassis;) |
:confused: :scratch:
I was looking for a way to screw my gainclone chips to the sides, with the same method. But I don't want to see the hoes from the exterior.
but tapering even 2mm in a 4mm deep hole is impossible, at leat with my tools |
|
|
| fedde |
Many toroids have an (oversized) internal fuse to prevent fire.
Can't you glue nuts inside the case to attach a metal bar with bolt to it that presses the chip to the case !?
Fedde |
|
|
| Peter Daniel |
| quote: | Originally posted by Bricolo
:confused: :scratch:
I was looking for a way to screw my gainclone chips to the sides, with the same method. But I don't want to see the hoes from the exterior.
but tapering even 2mm in a 4mm deep hole is impossible, at leat with my tools |
It seems like you are using 6mm panels, so this is close to 1/4" . I tapered #4 holes in that thick material (without going through) by using a tap which had the tip trimmed. It shouldn't be a problem. |
|
|
| ScottRHinson |
| quote: | Originally posted by Bricolo
OK, I understant.
There won't be a shorted turn going thru the center of the transformer, it's only bolted to the bottom of the chassis (but the top of the screw will be very close to the top plate)
PS: how can you see that a transformer is dead or damaged? |
In that case I would try to find a thin piece of surplus teflon to make sure that it never touches due to the toroid getting loose over time from vibration or any of the other reasons.
I doubt you killed your transformer with the caps, since transformers are made of metal and insulation they tend to be very tough devices when made well.
As a poster has already said use a DMM to check continuity and resistance...then check to make sure you're getting the right DC levels. If so, it's fine.
Scott |
|
|
| Bricolo |
fedde: where is this fuse located? In the toroid itself??!!
I've found another solution that yours using "external pression, instead of internal pression" (If I understood your idea, you're thinking about clamping the transformer by using a bar and bolts that are outside the transformer, am I right?)
Peter Daniel: I'll try. Thanks for the idea ;)
ScottRHinson: First, do you have a reference text that explains that we musn't have a metallical ring going thru the transformer's hole? You're the first that tells me about this (it seems quite logical, but you're still the first)
But I've found another solution as putting a teflon sheet:
A plastic bolt |
|
|
| Bricolo |
| Is the plastic bolt a good idea? |
|
|
| ScottRHinson |
| quote: | Originally posted by Bricolo
fedde: where is this fuse located? In the toroid itself??!!
I've found another solution that yours using "external pression, instead of internal pression" (If I understood your idea, you're thinking about clamping the transformer by using a bar and bolts that are outside the transformer, am I right?)
Peter Daniel: I'll try. Thanks for the idea ;)
ScottRHinson: First, do you have a reference text that explains that we musn't have a metallical ring going thru the transformer's hole? You're the first that tells me about this (it seems quite logical, but you're still the first)
But I've found another solution as putting a teflon sheet:
A plastic bolt |
You can have metal going through the center. It just can't go through the center and all the way around and complete a circle.
Scott |
|
|
| Bricolo |
| quote: | Originally posted by ScottRHinson
You can have metal going through the center. It just can't go through the center and all the way around and complete a circle.
Scott |
Ok, since my chassis has been made to be the flatest possible, the top could touch the top of the bolt...
I think that a M8 plastic bolt will be strong enough, but if someone has an opinion about this I'd like to knw it ;) |
|
|
| ronc |
Saw this in an earlier post.Go to a place that does industrial radiography.They use .005" and .010" thk. paper backed and coated lead sheets in up to 14"x17" for screens using Ir192 and Co60 radiographs.
ron |
|
|
| Bricolo |
| quote: | Originally posted by ron clarke
Saw this in an earlier post.Go to a place that does industrial radiography.They use .005" and .010" thk. paper backed and coated lead sheets in up to 14"x17" for screens using Ir192 and Co60 radiographs.
ron |
What kind of places makes INDUSTRIAL radiography?
I don't think I'll find those sheets in a hospital:scratch: |
|
|
| Gunderz |
| quote: | Originally posted by Peter Daniel
This is what I did in my preamp to isolate transformers. I've built a cage out of 1/8" copper plates and filled the space with epoxy. The AC connection is also done here on the bottom panel, right beside the transformer's housing. |
Nice chassis Peter Daniel, but I just wonder....
How did you manage to get text at the front, I would really like to know, my current amp has some knobs and switches and it would be nice to have some informative text related to them. |
|
|
| ronc |
What kind of forum is this? I was just trying to help? Someone had desired thin lead sheets and i responded to the answer with the knowledge that i have, i was an industrial radiographer for about 10 years, i dont believe i deserve flack for my response.They dont MAKE industrial radiograpgs they DO industrial radiographs.Its used primarly for x-rays ( x-ray being a radiograph from an x-ray tube, a gamma radiograph from a radioactive source) of weldments for petro chem and ship building and other apps that require quality control of a non destructive nature.
Sorry but sometimes this forum reminds me of a kiddy chat room in the responses, its hard in here to actually accomplish any gain in knowledge or find a real answer due to the immature postings.
thanks
ron |
|
|
| Bricolo |
| quote: | Originally posted by ron clarke
What kind of forum is this? I was just trying to help? Someone had desired thin lead sheets and i responded to the answer with the knowledge that i have, i was an industrial radiographer for about 10 years, i dont believe i deserve flack for my response.They dont MAKE industrial radiograpgs they DO industrial radiographs.Its used primarly for x-rays ( x-ray being a radiograph from an x-ray tube, a gamma radiograph from a radioactive source) of weldments for petro chem and ship building and other apps that require quality control of a non destructive nature.
Sorry but sometimes this forum reminds me of a kiddy chat room in the responses, its hard in here to actually accomplish any gain in knowledge or find a real answer due to the immature postings.
thanks
ron |
Please excuse me if you found my answear rude. I didn't write it this way.
Remember that I'm french, and I don't perfectly speak english. In our language, DO and MAKE is the same word...
I was just asking where exactly I could find such sheets, since I have no idea where industrial radiographies are DONE |
|
|
| Peter Daniel |
| quote: | Originally posted by Gunderz
Nice chassis Peter Daniel, but I just wonder....
How did you manage to get text at the front, I would really like to know, my current amp has some knobs and switches and it would be nice to have some informative text related to them. |
I used dry transfer lettering sheets (Letraset). You can find them in graphic supplies stores and it's very convenient and quick way to put the writing on a chassis. |
|
|
| ronc |
Thank you for your answer.
Lead sheeting used in industrial radiographs is used in petro chem plants, shipyards, ferrous casting plants and some pipeline applications.They are listed in the phone book (US) as industrial testing or industrial x-ray.
Hospitals do not use the lead screens as the wavelength of the radiation is too long to use for intensifying.
Lead is also a conductor which means it can also be used for RF shielding.
I am sorry for my response, but i keep seeing these responses in this forum that are non productive and are in the majority of un proven results.If i cant test it and either see a difference on a scope or hear an actual difference then i put it in the snake oil or BS file.
Nearly 30 years of Quality Control
in petro chem, aerospace ect ect has taught me this.
ron |
|
|
| jh6you |
| quote: | Originally posted by Bricolo
But I was thinking about placing a little sheet of damping material (very thin, lake a paper sheet) between all the places where 2 plates touch, this would damp the chassis vivrations
Good idea?
|
I do not know very well. But, the sheet material might give each plate different boundary condition so as to change the natural frequency of the plate. I do not know the effect of it as I do not know what is the purpose of the vibration control.
:yinyang: |
|
|
| Peter Daniel |
| quote: | Originally posted by Bricolo
But I was thinking about placing a little sheet of damping material (very thin, lake a paper sheet) between all the places where 2 plates touch, this would damp the chassis vivrations
Good idea?
|
Nobody's gonna tell you if it's good or bad idea, untill you try it yourself. It might work or not, and it's not so hard to check it out. |
|
|
| Bricolo |
Ok, I'll try when the chassis will be finished
Now, I'l looking for small AC inlets, with integrated fuse holder and double pole switch (non lightened). One that has to be fixed with screws, not clipsed in the plate |
|
|
| JOE DIRT® |
If I may interject...but it is common practice to use thin foam or silicone to dampen and or seal a plate to a cabinet
DIRT® |
|
|
|
