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Old 6th January 2012, 09:13 AM   #431
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Quote:
Originally Posted by danielwritesbac View Post
The datasheet says: "Wide ASO because of on chip ballast resistance."
Does this mean lossy output device can use either no or extremely small ballast resistors for paralleling?
I don't know what does it mean exactly. If there is a emitter resistor inside chip which recovers some drawback of transistor, it shouldn't be a good thing. At least we know that Circlophone doesn't use emitter resistors at output.
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Old 6th January 2012, 10:40 AM   #432
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Thank you very much!
I got this far (photo). Do you see any problems?
Attached Images
File Type: jpg Circlophone150w.jpg (238.1 KB, 268 views)
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Old 6th January 2012, 10:57 AM   #433
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Scale R26 for the new voltage drop?
Though I don't foresee Q1 exploding if you left it 2K2...

Q6 might be nearing its 80VCEO limit on the upswing.
Since this is always on, and base has pull down resistor,
the base here definately isn't "open" , I don't know if
VCEO limit matters? VCBO is 140V according to ST...

Last edited by kenpeter; 6th January 2012 at 11:12 AM.
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Old 6th January 2012, 11:30 AM   #434
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What value should I use for R26?

For Q5 and Q6, I found these TO220 available: 2SC5171, 2SC2073A
Are they appropriate?
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Old 6th January 2012, 12:18 PM   #435
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by danielwritesbac View Post
Thank you very much!
I got this far (photo). Do you see any problems?
Some remarks:

I would leave C5 on the right of R19: that's the normal RFI/band-limiting-filter configuration.
By placing it on the left, R19 becomes a base stopper. This could be justified, but only under very extreme and special circumstances, like Terranigma's.

It is preferable to leave C6 at 1.5nF.
1.2nF won't cause problems, but the optimum is at or near 1.5nF.

R26 has no active role, just damping and path-breaking. It could be reduced or omitted without problems, but should not be increased, as it will create supplementary poles with parasitic capacitances.


As Ken said, the 2N3019 are a bit on the edge for 84V, at least theoretically. I don't foresee any problem, but if you can sub them with 2N1893, that would be completely orthodox.
The 2SC5171 should work, the Cob is marginally high, but nothing alarming.
The 2SC2073 is completely unsuitable.

If you prefer, you can use a single 43V/1.3W zener, or two of 20V and 22V 400mW, the exact voltage is not critical anyway.


With the MJL's, C11 should not be implemented.

If you have the choice, use SR502 schottky's instead of SR506, they have a slightly lower drop.
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Old 6th January 2012, 12:50 PM   #436
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Thank you.
For subbing 2n3019 what about just using the complimentary partner to the driver, for easier shopping?
if q9/q11=2sa1209 then q5/q6=2sc2911?
or
if q9/q11=2SB649 then q5/q6=2sd669?

Or do I just need to stick with 2N1893?

Last edited by danielwritesbac; 6th January 2012 at 01:02 PM.
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Old 6th January 2012, 01:12 PM   #437
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Quote:
Originally Posted by danielwritesbac View Post
Thank you.
For subbing 2n3019 what about just using the complimentary partner to the driver, for easier shopping?
if q9/q11=2sa1209 then q5/q6=2sc2911?
or
if q9/q11=2SB649 then q5/q6=2sd669?

Or do I just need to stick with 2N1893?
I just realized that the 2SA1209 only has a 140mA Ic rating, so it's out.

The 2SD669 is OK as phase splitter
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Old 7th January 2012, 12:01 AM   #438
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I'm currently working to "modernproof" D7 to avoid "reproductions" with inaccurate datasheets.

For these four, the datasheets should be reasonably accurate.
Are any of these high availability parts suitable for D7?
1n5819 40v
1n5822 40v
1n5711 70v
1n6263 60v

It seems that D7 is the last piece of the puzzle for circa 2012 parts list.

P.S.
I have updated the "extra power" schematic with current production ST 2n1893 at Q5/16.
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Old 7th January 2012, 02:48 AM   #439
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Quote:
Originally Posted by Elvee View Post
I would leave C5 on the right of R19: that's the normal RFI/band-limiting-filter configuration. By placing it on the left, R19 becomes a base stopper. This could be justified, but only under very extreme and special circumstances, like Terranigma's.
The attached radio does output some RF.
If at the right of R19, the efficient little cap will increase amplitude of noise at pitches directly lower than the intended filtering; so, how about an RC for RF instead of just the cap?
Quote:
Originally Posted by Elvee View Post
It is preferable to leave C6 at 1.5nF.
1.2nF won't cause problems, but the optimum is at or near 1.5nF.
Okay. Thanks!
Quote:
Originally Posted by Elvee View Post
If you prefer, you can use a single 43V/1.3W zener, or two of 20V and 22V 400mW, the exact voltage is not critical anyway.
Upon reading the whole thread again, it seemed that everyone had slightly more V+ than zener, so I marked down a 2 of 20v zener (40v)--The little package of a minimum purchase typically has 4 or 5 zener, so maybe it is convenient. If there is a problem, please mention it.
Quote:
Originally Posted by Elvee View Post
With the MJL's, C11 should not be implemented.
Okay. Thanks!
Quote:
Originally Posted by Elvee View Post
If you have the choice, use SR502 schottky's instead of SR506, they have a slightly lower drop.
If I buy new production SR502, they will be SR506 with an SR502 paint job. That doesn't make a different part, just a less accurate datasheet. If you'd like a different part, we'd need to find it in some other IC package size, at least. I don't mind using a more expensive part as long as it is easily available, so please indicate if you want that.

So, for wrapping up some schematic and parts list documentation:
1). A really good performing D7 of current production and high availability?
2). Need to know if any resistors continuously pull more than 1/8w?
3). Proof the parts list and "extra power" schematic one last time.
4). Make a power supply somewhat auto adapt to speaker load
5). Find a PCB photo that is preferred/accurate?
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Old 7th January 2012, 08:09 AM   #440
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Quote:
Originally Posted by danielwritesbac View Post
The attached radio does output some RF
Do you use it with a radio transmitter?
Quote:
If at the right of R19, the efficient little cap will increase amplitude of noise at pitches directly lower than the intended filtering; so, how about an RC for RF instead of just the cap?
Why would the cap increase the amplitude?

Quote:
If I buy new production SR502, they will be SR506 with an SR502 paint job. That doesn't make a different part, just a less accurate datasheet. If you'd like a different part, we'd need to find it in some other IC package size, at least. I don't mind using a more expensive part as long as it is easily available, so please indicate if you want that.
The schottky's role is minor, they simply improve the energetic efficiency and could be omitted without problem, there is no need for high performance there.
A reverse voltage of less than 5V is more than sufficient, but each has to carry half of the output current, which rules out the 1N5822.
The 1N5711 and 6263 are poor choices for the clipper: they are high voltage/low current, low conductance types, better stick with BAT8x types.
Quote:
2). Need to know if any resistors continuously pull more than 1/8w?
Many do at Vs=40V, and even the ones that don't should be oversized.
The whole circuit has been designed to use exclusively 0.25W resistors and finding the one or two exceptions makes little sense.
Quote:
4). Make a power supply somewhat auto adapt to speaker load
I do not see how this could be implemented without huge complications.
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