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Old 13th March 2011, 03:09 AM   #991
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I've run mine from 3 X 9V batteries for 27V. Because it only draws 12mA you can get about 50 to 100 hours of play out of lithium non-rechargables.

The other way I powered BoZ is with external plug-pack transformer, diode bridge and some big filter caps. My BoZs have 20,000uf to 30,000uf of filter cap on the board with the rest of the components.

I've never had any hum or noise yet.
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File Type: jpg BoZ_IIss.jpg (121.3 KB, 745 views)

Last edited by mhouston; 13th March 2011 at 03:10 AM. Reason: typo
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Old 13th March 2011, 04:11 AM   #992
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I usually leave my amps on all the time so battery will not be practical.

Can you help with a schematics for the power supply. Or would a 18V wall wart that i use for a B1 work with this BOZ Jfet.
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Old 13th March 2011, 05:59 AM   #993
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Quote:
Originally Posted by xecluded View Post
I usually leave my amps on all the time so battery will not be practical.

Can you help with a schematics for the power supply. Or would a 18V wall wart that i use for a B1 work with this BOZ Jfet.
What I found was the SMPS wall wart worked with the B1 but buzzed with BoZ. I think part of the reason is B1 has negative gain (haha) and better PSRR. BoZ has gain and poor PSRR. There is no need at all to leave these units on 24 X 7. As long as you are using them often, turning them on 20 mins prior to use should be enough.

If you want the schematic to my remote PSs let me know. But remember I have very large caps right on the cct. brd.
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Old 15th March 2011, 01:54 PM   #994
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If you want the schematic to my remote PSs let me know. But remember I have very large caps right on the cct. brd.
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That's alright. It's too much trouble. I will just stick with the B1 and enjoy. Thanks.
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Old 15th March 2011, 02:14 PM   #995
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Check-out Juma's BF862 design that give a gain of 2 to go in front of the F5 - rather neat supplies, easily scalable.
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Old 16th March 2011, 12:22 AM   #996
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Hello everyone.So many times when I google some idea I have I'm directed to diyaudio.
Some good ideas floating in here for sure.Love the pictures too.
Well I need a preamp and found out about Nelsons JFET BOZ.
So today I built one.
Put it on one of the small pcbs you get a R.S. the kind that comes two to a package.
I didn't split the two boards and built the left and right side of course as mirror images of each other.
The right side gets 15.5Vdc from the power supply but the left side only shows me 5.5Vdc.

Did I make a voltage divider and not know it?Has something like this happened already to another builder?
Any ideas?I will be back at it again tomorrow to troubleshoot this board.Will look to see if I have everything were it should be.The fact that the right side is good makes me think I have a component in the wrong place or I have a leg from one component were it does not belong.

Also maybe you could answer me this.
What mechanism do I use to tie the two boards together of course for the stereo effect?
I'm using 15.5vdc so how do I get 15vdc to both the left and right side simultaneously?
When I put the signal from my CD player to the board I ran it this way.
Signal in from CD player to B25k linear pot,pin one,to pin two (wiper)out,to the junction of 1k & 1M ohm resistor.Pin 3 of the pot to ground.
Audio out is from 475 ohm resistor to the main amp audio in via RCA.
I get a loud hum which will not vary with the volume up or down and I can hear some music.
Should the RCA in and out both be grounded?
Plus I'm a bit confused about grounding the circuit needless to say.Seems like I either have too many points grounded or not enough and not just on this project.
I have read 40+ pages on this thread but to tell you the truth...going through the next 60+ pages probably will not help me to get this thing running.
Just a few simple answers may put me in the correct direction.Any help you can give me is greatly appreciated.
Thank you Nelson Pass for the design and for publishing it for us to use.
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Old 16th March 2011, 10:33 AM   #997
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post pics (800*600 is detailed enough) of the back and front of your assembled CB.
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Old 16th March 2011, 11:24 AM   #998
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Old 16th March 2011, 12:57 PM   #999
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Here are some pics.
Front and back.
Believe it or not none of the legs of components touch each other.
Attached Images
File Type: jpg Jfet Boz pics 001.JPG (658.4 KB, 592 views)
File Type: jpg Jfet Boz pics 002.JPG (656.4 KB, 544 views)
File Type: jpg Jfet Boz pics 003.JPG (669.6 KB, 477 views)
File Type: jpg Jfet Boz pics 004.JPG (672.7 KB, 443 views)
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Old 16th March 2011, 01:04 PM   #1000
AndrewT is offline AndrewT  Scotland
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are we supposed to pick out detail from those?
crop to CB size.
post at 800*600 and use daylight not flash offset to one side.

If you must use flash then get two set up to both sides and aimed at ~ 45degrees to the CB so that we don't see reflections and the CB is fairly evenly lit.
Simpler to use outdoor daylight.
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