visual identification /recognition ---of a 12 volt one watt zener diode already attached to a old ci

[ZAMDUDE]

Success !! got the devil working !!--Finally ----

After so many failures --I constructed the last single power supply schematic --( fig 15 --)

TOTALLY silent ----no sound at all ? --puzzled !

And then ---frustration -----started removing /replacing all the capacitors with higher values --no good
Then I removed the two 22 UF caps --replaced them (stupidly I thought)
with much smaller 10 MF CAPS ------ THEN SMALLER STILL----4 .7 mf --16 volts
BOOM --speaker came to life !!---STUNNED !
perfect voice reproduction thru 50 k var pot ------loud CLEAR --ZERO DISTORTION !
MIKE even feedsbaCK --WOW ! -----
That's a sure sign of amp gain ----
Yet the datasheet states ---"smaller caps = gain loss ?'" --

Well --that's proven to be incorrect -------just fiddling with caps ---took a huge gambol --
expected the IC to burn out !
IT remains luke warm --even after loud mike shouting ----------- and the huge heat sink is now half size --4 inch 7 2 inch alumin channel --stays cold --under full load ----got to be ok ?

Nuff said ----it works ---happiness is finding out the hard way by my self !
Now to build the much easier 18 volt --TDA 2040 -------- THE ONE I use as a PRE-AMP !-7 yrs --no probs --at least I know it works --!

so I will make a 24 watt -- microphone amp --just to us up those idle dusty IC ,S ----thank goodness I solved the 2006 PUZZLE !
7 years ----drove me to try any tricks =-------well ----small battle won --

many thanks AUDIO -----appreciate your help ( appears you have never tried to build this TDA 2006 --!perhaps you are too busy
pouring scorn on spaghetti chips ----?
NEVER MIND ------ Will post fotos or video --if u still doubt amateurs can succeed!
best regards ----- Zendode
-----

 

[audioguru]

For the TDA2006 datasheet schematic in figure 15:
1) The 22uF capacitor on the left is a filter for the two 100k biasing resistors. Its time constant is (100k//100k) x 22uF= 1.1 seconds so it filters out the 100Hz or 120Hz hum from an AC to DC power supply pretty well. A smaller capacitance will filter less and maybe the hum will be heard.

2) The 22uF capacitor on the right blocks DC for the negative feedback. Its produces a low frequency cutoff of -3dB at 1.5Hz which is way too low and the Italian designer made a huge error. 2.2uF will be fine for audio.

The amplifier should not be silent with 22uF capacitors unless they were connected with backwards polarity. The negative wire of each capacitor connects to ground.

 

[ZAMDUDE]

SGS Thomson micro-electronics --

are a French --Italian --consortium --based in Amsterdam --now known as ST microelectronics ---

Thankyou for all that mind-
numbing theory /analysis ---you are way beyond my comprehension !

If you had taken the trouble to actually construct this AMP -as I requested=----instead of \\\\assuming I connect Capacitors backwards and my circuits are badly made ---

You would then have answered my question ---
PROOF is in the pudding ---IT WORKS BEYOND MY EXPECTATIONS !

However --you are possibly correct when you say the Italian or French or Dutch tech made a booboo --with the 22 uf caps

Why ----do the 4.7 MF caps work ???---
replaced both 22 mf caps -----even lowered the 4,7 K OHM resistor ----to 3,3 K OHM---
GAIN increased !
NO HUM ! --NO more snap crackle Or POP !--
TDA amps are very resilient with temp control built in ---
But I bow to your superior knowledge -----
Just wanted you --all along --to construct this 2006 single supply for me ---
surely that way --you would have picked up any errors ----

My slap bang amateur method worked --surprisingly ----so I am quite satisfied ---
I can build all these amps quite easily now ----SANS all the monster theory ----
Why you refuse to actually post a IMPROVED SCHEMATIC of SGS THOMSON --smallish error circuit --
is way beyond my understanding --shud be a piece of cake for you hi-tech experts !!

I/m simply a retired Pro hunter /wildlife artist -----I take the time & trouble to give my students PRACTICAL - Illustrations-WITH theory
Drawings /schematics / diagrams --all help ENORMOUSLY to explain complex theory ---
but I still read the Gibbilisco manuals on square wave --frequency --flip- flop circuits -saw tooth waves ---oscillation etc etc --
still a long way to go -----
appreciate all the theory ------
will digest slowly
regards Zendude

 

[audioguru]

You reduced the value of the 4.7k resistor. Its ratio with the feedback resistor normally determines the gain so of course the gain increased.

Wait a minute. One circuit in the datasheet has a 22k feedback resistor and a 680 ohm resistor in series with a capacitor to ground (gain= 33.4 times), but another circuit has a 150k feedback resistor with a 4.7k resistor to ground (gain= 32.9 times).
If you wrongly used a 22k feedback resistor with a 4.7k capacitor in series with a capacitor to ground then the gain is too low at 5.7 times which will guarantee oscillation at a high frequency causing heating and severe distortion. The datasheet does not say the minimum allowed gain that is shown on amplifier IC datasheets made by other manufacturers. But ST Micro does show the optional dotted R5 and C8 and graphs showing their effect on bandwidth, which might prevent oscillation when the gain is too low.

 

[ZAMDUDE]

Please --build this circuit ----you will then realise-----
(--change the 22 mf caps ----( simple )

its a dynamic blast --no overheating ---no oscillation --no more --clear voice /clean guitar --even shouting in the mike
cannot produce distortion ------heat sink stays ice cold --

Quite happy ---all me own sweat ---apologies --your verbal analysis has little meaning to me --
but I will get it all one day ----
building Amps is really interesting --keeps me progressing to bigger & bigger !
( ok my theory sucks --but that can be overcome )

Give me a corrected sketch ?
regards -- Z

 

[Old dog]

"One who conquers himself is greater than another who conquers a thousand times a thousand on the battlefield."
- Buddha
well done. old school tech

 

[ZAMDUDE]

Thanks Old Dog ---appreciate --the compliment ---

Edison had little formal education ---so did Tesla ---
--and they succeeded beyond all expectations ----We all owe them -and Bell Labs semiconductors----a great debt of gratitude!