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U1 fried

Michael Hagen
 

I wonder if a small light bulb. like the old standby #47 could protect a speaker short.

Maybe some type fast lo-mass fast Thermistor?   Something that has small resistance, but goes up quickly with a short.

Just thinking crazy.

Mike, WA6ISP



On 2/28/2018 4:06 PM, Clark Martin wrote:
The chip is rated to work with a 4Ω load so a 4Ω resistor should do.  I doubt the chip would blow so fast that FB fuse wouldn’t protect it.


Clark Martin
KK6ISP

On Feb 28, 2018, at 4:00 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

Better be a pretty darn fast fuse.

I'll go with an 8 ohm 1/2 watt series resistor to limit current.
At least till I find a good source for TDA2822M chips.
I'm fairly certain that resistor will offer sufficient protection.






-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
Mike@...

John
 

I ordered on eBay. Ordered the TDA2822L and the TDA2822M.
The L comes from the US and I paid $3.99 for 5
The M comes from China and I paid $2.75 for 10.
So at least I will have some spares.

First ordered the Ms butbthat will be a long wait. So after I saw the La in the US I ordered those as well.

John

Jerry Gaffke
 

Now that we have a bunch of sources for the part,
I might be more inclined to experiment.

Resistance of a small incandescent bulb can go up a factor of 10 when it gets hot:  https://groups.io/g/BITX20/message/21901 
That or a fuse would be easier to replace than an 8 pin dip.


On Wed, Feb 28, 2018 at 07:10 pm, Michael Hagen wrote:

I wonder if a small light bulb. like the old standby #47 could protect a speaker short.

Maybe some type fast lo-mass fast Thermistor?   Something that has small resistance, but goes up quickly with a short.

Just thinking crazy.

Mike, WA6ISP

 

Michael Hagen
 

Pilot Lamp Bulbs.

Here is a chart from the past.  Guys that build tube guitar amps still buy them.

#47 was the most popular when I was a kid, #44 to get more Light.

There would be a lot of experimenting to see if they would work to protect the amp.

What impedance speaker you are using would be a big factor too.

73's

Mike, WA6ISP

 

On 2/28/2018 7:29 PM, Jerry Gaffke via Groups.Io wrote:
Now that we have a bunch of sources for the part,
I might be more inclined to experiment.

Resistance of a small incandescent bulb can go up a factor of 10 when it gets hot:  https://groups.io/g/BITX20/message/21901 
That or a fuse would be easier to replace than an 8 pin dip.


On Wed, Feb 28, 2018 at 07:10 pm, Michael Hagen wrote:

I wonder if a small light bulb. like the old standby #47 could protect a speaker short.

Maybe some type fast lo-mass fast Thermistor?   Something that has small resistance, but goes up quickly with a short.

Just thinking crazy.

Mike, WA6ISP

 


-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
Mike@...

Clark Martin
 


Clark Martin
KK6ISP

On Feb 28, 2018, at 4:45 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

Ah, the TDA82822D part in the SOIC8 package is a good find.
Feeling much better now!

Digikey has it for a bit over a dollar (Mouser says a minimum buy of 2000).
Maybe hfsignals will move to the more easily gotten SMD part if they ever roll the board.
Though I'm pretty sure I could solder the SMD into place with just some short wires, 
not bothering with the adapter board.

Mouser has it for $1.19, minimum buy of 1.  The part number is listed as TDA2822D013TR.  The data sheet doesn’t show anything about the 013TR suffix so it’s likely referring to packaging variation (tube vs cut tape).

As to soldering it in directly, I do something like that.  If it fits you can place it over the pads and solder the inner two pins on each side right to the pads then tack solder fine wire to the outer two pins on each side and then to the pads on the PCB.  I use wire-wrap wire, sans insulation.

 

Jerry,

TDA2822D is LOW power compared to the 8 pin DIP. Check and compare.. the 16 pin DIP has even greater output!

Raj

At 01-03-2018, you wrote:
Ah, the TDA82822D part in the SOIC8 package is a good find.
Feeling much better now!

Lawrence Galea
 

As found on a post, a component will sacrifice itself to protect the fuse.
I suggest using a 7808 to supply the TDA amplifier with a lower voltage and also provide current limit protection.
There is also the choice of using a complete cheap audio amplifier that one can find on ebay, bangood etc.
They are cheap and it would probably cost you more to build it yourself.
Regards
Lawrence

On Thu, Mar 1, 2018 at 1:06 AM, Clark Martin <kk6isp@...> wrote:
The chip is rated to work with a 4Ω load so a 4Ω resistor should do.  I doubt the chip would blow so fast that FB fuse wouldn’t protect it.


Clark Martin
KK6ISP

> On Feb 28, 2018, at 4:00 PM, Jerry Gaffke via Groups.Io <jgaffke=yahoo.com@groups.io> wrote:
>
> Better be a pretty darn fast fuse.
>
> I'll go with an 8 ohm 1/2 watt series resistor to limit current.
> At least till I find a good source for TDA2822M chips.
> I'm fairly certain that resistor will offer sufficient protection.






Claude-Alain Baumgartner
 

The TDA2822 obviously can not stand the 12V. After having blown two TDA2822's, I soldered a socket in its place, and made an adapter for the LM386, which never failed at 12V.
Here is the wiring:

LM386 pin:     2  -  4   TDA2822 corresponding pin
                       3  -  7
                       4  -  4
                       5  -  1
                       6  -  2

Very simple and effective.
73's
HB9CGL Claude

Mike Yancey
 

https://www.taydaelectronics.com

US$ 0.19 (nineteen cents) for the 8-pin PDIP / US$ 0.73 for the SMT version.

Mike Yancey, KM5Z
Dallas, Texas

Bill KC5SB
 

I ordered mine from eBay - plan to use the socket this time.  Should arrive today.  Still have to wait for my R75 replacement though.

https://www.ebay.com/itm/5PCS-STMicroelectronics-TDA2822M-TDA2822-Sockets-Dual-Audio-Amplifier-New-IC/292172486301?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Rick Price
 

My brother-in-law and I each have a radio that we received last week,
ordered 12-25-17. Speaker and amp chip have worked great with no heat unitl
last night. Last evening he turned his radio on and the TDA got very hot
and started smoking for no reason at all. Current went up to almost 1 amp in
receive as it got hot. Beginning to believe there is a batch of bad chips.
Already ordered several replacements and sockets. I am going to try the
speaker lead 4 ohm resistor in mine before it goes.

Rick
KN4AIE

Vince Vielhaber
 

Is it too late to get the mfgr and date code from that bad chip?

Vince.

On 03/01/2018 12:02 PM, Rick Price wrote:
My brother-in-law and I each have a radio that we received last week,
ordered 12-25-17. Speaker and amp chip have worked great with no heat unitl
last night. Last evening he turned his radio on and the TDA got very hot
and started smoking for no reason at all. Current went up to almost 1 amp in
receive as it got hot. Beginning to believe there is a batch of bad chips.
Already ordered several replacements and sockets. I am going to try the
speaker lead 4 ohm resistor in mine before it goes.

Rick
KN4AIE


Rick Price
 

I'll have him save it as he is taking it out of the board as I write.  Don't know if the writing is still legible.
Rick

K4LXY
 

Claude
I note you have 2 to 4, and 4 to 4.  Are there two wires going to the TDA pin 4?
Howard K4LXY

K4LXY
 

In other words, you are eliminating one of the amps that is in the TDA, and grounding one of the inputs to the 386.  Right?
Howard

Jerry Gaffke
 

Yes, 2 wires to TDA pin 4.

TDA pin 4 is ground on the uBitx.
LM386 pins 2 and 4 are both ground on the Bitx40, and thus both must be wired to TDA pin 4.

Claude has left pins 1 and 8 of the LM386 unattached, the LM386 datasheet states that
in this configuration it has a voltage gain of 20, or 20*log10(20) = 26dB.
The LM386 on the Bitx40 has a 0.1uF cap between pins 1 and 8 to increase the gain to 46dB.
The original TDA2822 of the uBitx has a gain of 40dB, so you may want to try adding a cap between LM386 pins 1 and 8
if you need more gain there.  A larger value cap (up to 10uF) would improve low frequency response.



On Thu, Mar 1, 2018 at 10:20 am, DrZ wrote:
I note you have 2 to 4, and 4 to 4.  Are there two wires going to the TDA pin 4?

K4LXY
 

Thanks, Jerry.  I have an adapter made and will give it a try.
Howard 

Claude-Alain Baumgartner
 

Hi Howard,

Yes, both pins 2 and 4 of the LM386 go to pin 4 of the socket (ground).

Regards,
Claude

Mike Woods
 

Hi everybody

I have tried to summarise what we know about the TDA2822 problem, prevention and fixes in this article on ubitx.net:

http://ubitx.net/2018/03/01/tda2822-problems/

Let me know if you can suggest further improvements to my text.  We don't want 2000 µBITx owners to go through the same pain as some of you have experienced ...  I hope to insert a resistor in the output circuit today!

73 Mike ZL1AXG


On 2/03/18 9:50 AM, Claude-Alain Baumgartner via Groups.Io wrote:
Hi Howard,

Yes, both pins 2 and 4 of the LM386 go to pin 4 of the socket (ground).

Regards,
Claude


--
Mike Woods
mhwoods@...

MVS Sarma
 

Whether it could be batch wise observation?
 I don't remember such cases reported earlier


On 2 Mar 2018 02:25, "Mike Woods" <mhwoods@...> wrote:
Hi everybody

I have tried to summarise what we know about the TDA2822 problem, prevention and fixes in this article on ubitx.net:

http://ubitx.net/2018/03/01/tda2822-problems/

Let me know if you can suggest further improvements to my text.  We don't want 2000 µBITx owners to go through the same pain as some of you have experienced ...  I hope to insert a resistor in the output circuit today!

73 Mike ZL1AXG


On 2/03/18 9:50 AM, Claude-Alain Baumgartner via Groups.Io wrote:
Hi Howard,

Yes, both pins 2 and 4 of the LM386 go to pin 4 of the socket (ground).

Regards,
Claude


--
Mike Woods
mhwoods@...