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Old 14th April 2013, 01:25 PM   #8851
dvv is offline dvv  Serbia
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In terms of time of appearance, yes, the JBL preceeds the Hitachi by about 5 years or so.
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Old 14th April 2013, 01:51 PM   #8852
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One thing I did try was what I think is called a Wilson current mirror ? I liked it because it needs no biasing resistors . From what I remember it had impressive mathematical qualities . However real life saw nothing I could measure . As daft as it might seem the amp as drawn in someways has the most merit . That is ,complex current mirror and simple tail resistor . The previous examples gave RC filtering which I did not repeat . What could be said is small power supply the the 47 K tail resistor would be ideal . At 1 mA it need not cost much .

Wilson = 3 transistors ? Here are some worked examples . I note elsewhere complimentary versions .
http://sound.westhost.com/ism.htm#p7

Last edited by nigel pearson; 14th April 2013 at 01:59 PM.
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Old 15th April 2013, 11:20 AM   #8853
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Please forgive this ancient drawing of mine . I have updated it with what I see as sensible improvements .

I noticed from my notes that a 1N series diode is a poor match for the 2SB716 transistor . A pair of MPSA 92 I imagine would be better ( and cheaper ) ? Remember the Hitachi has exemploray HF performance , it should not be assumed that a change is always for the better .

The time constants of the pink resistor ( filters ) are the first values that came into my head , doubtless these can be improved ?

The CCS to the LTP is optional . If so replace with 47K .

The VAS clips before the outputs which will make for a nicer clipping spectrum .

Any ripple will be lost in the 5V VAS to output difference .

The VAS is a 120 V device , the outputs 160 V . +/- 63 V as a maximum , 56 V typical to suit 63 V capacitors .

Note . Voltages approximate .

Last edited by nigel pearson; 15th April 2013 at 11:48 AM. Reason: Add note .
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Old 15th April 2013, 12:42 PM   #8854
dvv is offline dvv  Serbia
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Gee Nige, you're into fireworks now?

Switch it on and your input "-" power line 220 uF cap goes "boom" because it's turned the wrong way around in polarity.
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Old 15th April 2013, 02:16 PM   #8855
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The one that got away ! Thanks for looking that carefully . Doubtless something else ? It happens in real life . A PCB mask with the wrong labeling . It happened to me recently . One diode . I was happy as all the bits I had great doubts about worked fine .

Last edited by nigel pearson; 15th April 2013 at 02:36 PM.
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Old 28th April 2013, 09:00 AM   #8856
dvv is offline dvv  Serbia
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Anyone alive?
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Old 28th April 2013, 09:31 AM   #8857
godfrey is offline godfrey  South Africa
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Barely. Wassup?
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Old 28th April 2013, 10:31 AM   #8858
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My son just asked me to help him build a FM transmitter . He has the BA1404 chip . Pin 5 usually has a 38 kHz crystal followed by 10pF into pin 6 ( loading ? ) . I know a series capacitor will push a crystal up in frequency . I guess 18% up is asking a lot ( watch crystal ) . Pushing a 9.8304 MHz crystal down by 1% seems possible ( guess at 220 pF ) . Doubtless pin 6 doesn't need a cap . It is there to remind me of options . The 74HC4060 at Q8 is divide by 2 power 8 ( 256 ) = 38.4 kHz . I would guess 38.4 kHz to be usable ? 38 kHz crystals are rare . 5 may be the input or 6 I haven't got there yet .

Not knowing much about BA1404 I speculate that it is like the 4060 ? I seem to remember those will work as RC oscillators ? Perhaps a 100 pF NPO 39K 1% and 5K pot would work ? L1 seems to be 10 uH ( adjustable ) . Any thoughts ?

I use a little mono FM transmitter bough for $8 at a petrol station . It works very well .
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Old 28th April 2013, 06:27 PM   #8859
dvv is offline dvv  Serbia
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@Godfrey

Nothing really, I was just wondering why the deafening silence all of a sudden?

For myself, I've been busy trying to find employment for my son. Not at all easy in a country with around 40% of work force unemployment. That's what I've been decdicated to for the last 2 years, give or take a month.

As the good Lord sayeth "He who waits shall receive", and I (my son) hath received. We did wait for quite a bit, but in return he landed a job with a whopping big company very well off (the do development and construction work mostly abroad, mostly in Russia). He started working on 1st of this month, and is in a progarm to work for a few weeks in various departments, the idea being to learn what suits him best and where he will be most useful to the employer - I'd call that a godsend, this opportunity to actuall pick his own type of work.

You can imagine just how pleased I am, and the son is as well. He's the opposite of a layabout, the time we were looking for a job he spent getting his master's degree - all that's left is the formal end paper exam, but that's realy just formal, so he'll be receiving his degree in early June, I expect, lots of administrative loops in between, but again, all formal.

As the icing on the cake, melady wife is in Berlin for a large medical gathering, returning on Wednesday evening, giving me 6 days to catch my breath.

@nigel

Off into the world of FM broadcasting I see.

Nige, is there anything you don't do?
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Old 28th April 2013, 06:59 PM   #8860
bcarso is offline bcarso  United States
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Quote:
Originally Posted by dvv View Post
@Godfrey

Nothing really, I was just wondering why the deafening silence all of a sudden?

For myself, I've been busy trying to find employment for my son. Not at all easy in a country with around 40% of work force unemployment. That's what I've been decdicated to for the last 2 years, give or take a month.

As the good Lord sayeth "He who waits shall receive", and I (my son) hath received. We did wait for quite a bit, but in return he landed a job with a whopping big company very well off (the do development and construction work mostly abroad, mostly in Russia). He started working on 1st of this month, and is in a progarm to work for a few weeks in various departments, the idea being to learn what suits him best and where he will be most useful to the employer - I'd call that a godsend, this opportunity to actuall pick his own type of work.

You can imagine just how pleased I am, and the son is as well. He's the opposite of a layabout, the time we were looking for a job he spent getting his master's degree - all that's left is the formal end paper exam, but that's realy just formal, so he'll be receiving his degree in early June, I expect, lots of administrative loops in between, but again, all formal.
Congratulations on your son finding work.
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