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Old 8th December 2006, 05:05 PM   #21
Fuling is offline Fuling  Sweden
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Dont get too excited, I have no software for drawing schematics so the new ones will also be drawn by hand but Ill try to make them readable (ist that a word?).

Right now, Im trying to decide what Mosfets to use in a bigger version of the cascoded Zen, I have a few types to choose between but none of them are optimal. OTOH Id prefer to use parts that I already have at home...
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Old 8th December 2006, 09:16 PM   #22
Paper mache horn fabricator
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You can download a free copy of schematic drafting software from Express PCB. I use it to draft electronic circuits as well as an aid to designing my pcbs.

btw, speaking of pcbs, I'm firing up my newest version of the ZV7-T today. My circuit boards are working perfectly, so far. The only glitch is my power resistors (Q1 and Q2 drain to ground) are getting hot. I can't even begin to touch them. I'm thinking about using the "light bulb" technique to replace the power resistors. I just have to find which wattage gives me 47 ohms.

Here's to hoping you have a wonderful week-end.

John
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Old 8th December 2006, 09:28 PM   #23
Fuling is offline Fuling  Sweden
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Ok, Ill have a look at the free software whenever I get the time to do it.

Drain to ground, I assume that would be output to ground (I dont have the schematic in front of me right now)?
If so, Id use bigger power resistors instead of lightbulbs.
In my world lightbulbs belongs in lamps, not between output and GND in power amps
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Old 8th December 2006, 11:42 PM   #24
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I built a heatsink array around the power resistors and now they are quite happy--or maybe, I'm quite happy.

John
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Old 8th December 2006, 11:45 PM   #25
Fuling is offline Fuling  Sweden
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Good! Dont bother too much about power resistors running hot, they are designed to do that!
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Old 8th December 2006, 11:49 PM   #26
Paper mache horn fabricator
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They were hot! The paint on the plywood box they rested against melted... Now, the heatsink keeps them around 50 degrees C.

John
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Old 9th December 2006, 02:38 AM   #27
lineup is offline lineup  Sweden
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Quote:
Originally posted by Fuling

I have no software for drawing schematics
so the new ones will also be
drawn by hand .....
.
Quote:
Originally posted by carpenter

You can download
a free copy of schematic drafting software
from Express PCB.

I use it to draft electronic circuits
as well as an aid to designing my PCB.
.
thanks, carpenter

www.ExpressPCB.com Download.htm

I decided to try.
I downloaded latest version, May 2006.
It is a good and very easy to use Schematic program.


Two parts:
1. ExpressSCH ... for adding components symbols and wires into a schematic
The Circuit can be exported, Saved, directly to a .BMP image, with different selectable resolutions
or
The Circuit can be Copied to Clipboard and so imported into your Image program.
And from there saved in what format you like: PNG, GIF ....

2. ExpressPCB ... for creating PCB Layout from your circuit
This one I did not test,
because I don't make PCB
.. there are so many members at this forum
that can do this much better .. if we ask them nicely

==========================================


Carpenter,
thanks for the hint about ExpressPCB www.expresspcb.com
Easy and good tool for diyaudio members. (I guess only for Windows users, I have XP Home)

Carpenter,
as a reward you can freely use my circuit I created quickly using this ExpressSCH software.
While I was learning how it works.
( I even did not have to consult the 'Quick Guide' or 'Help documents'! )

All you others
Please note and respect that this Attachment below
is for carpenter only!!!!!

lineup
Attached Images
File Type: png lineup-op-dual-output_1.0.png (18.6 KB, 184 views)
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Old 9th December 2006, 05:24 AM   #28
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Default Thanks, lineup

What a sweet layout.

I'm still studying it's properties, but I see I can have a bunch of fun with this.

Balanced front end
Fet for bias voltage
Push/pull output
All transistors have their own ccs

very cool, and I'm glad you enjoyed the software,

John
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Old 9th December 2006, 05:59 AM   #29
lineup is offline lineup  Sweden
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- not to mention balanced in and/or output
- input for driving two power amplifiers in bridge ( one from +out and one from the -out

Most Non-Lineup operational amplifiers
have only one non-inverting output.


1. Resistor in JFET CCS source, should first be adjusted,
to get like 0.6V in that current source feeding two input transistors.
The current in those 1N4148 diodes
determines this voltage across R1 ~ 0.60 Volt.

2. Those other two trimmers (one for CCS in +output, the other for -output stage)
should then be used to achieve balance at the output stages.
We can say this is the Output DC-offset adjustment.

3. Can of course like most Op-Amps be used with single or dual supply.
For single supply, we need input and output caps, of course.

4. Each output stage has got idle Class A!! ~6mA ( 0.6V/100 )
Can for example drive +-4-5mA into 5 kohm= +-20-25 peak ~15 Volt RMS

5. BF245A .. the JFET is only for 30 VDS. So max dual +-15V if using that one.
Use some other JFET, for higher voltage operation.
There are some 40-50 Volt JFET that are easy to find.
For example 2SK170 takes 40 Volt = +-20Volt operation

6. BC550C, BC560C takes 45V, so max +-23 Volt supply for them.

7. By using other types of JFET and BJT small signals
you may tailor your Op-Amp for much higher voltages,
higher currents output
or whatever.


lineup
PS. I hope Fuling decide to download ExpressPCB.
It is a tool what many would need.
Instead of trying to describe circuits with words ... DS.
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Old 9th December 2006, 02:19 PM   #30
Zen Mod is offline Zen Mod  Serbia
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for any paint
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