Date   
Re: U1 fried

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

Re: TDA2822 ill treatment test!

Dexter N Muir
 

p.s. another 'cheapo' move: no output caps. :)

Re: Stereo jacks with kit wiring guide #bitx20help

@bobbybailey
 

when I try to read the information in the drawing, it is all fuzzy and unreadable, can you send me a file that I can print out and be readable ?
thank you.

Re: U1 fried

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

Re: U1 fried

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?

Re: full rig power control unit

Michael Hagen
 

By the way, I see a lots of requests for Package Layouts, pre-done.  People really worry too much about that.

What they should worry is how hard is the learning curve for making your own packages and schematic symbols.

I almost always make my own packages from the IC drawing or what ever I am making a model for.  Most packages that come with the Layout software were done by someone other than an engineer or someone familiar with layout.

I always try to have Pin1 at 0,0.   No matter what the outline around the part is, always try to make a pin (1) the reference point.

Jerry didn't not mention what the cost of Pads was, I bet over $10K.  And maybe another couple K PER YEAR to keep the license up.

73's

Mike, WA6ISP


On 3/1/2018 9:35 AM, Vince Vielhaber wrote:
Yeah that's kinda what I thought.  I have a double sided board I'm working on that's only about an inch by an inch and a half and has 3 ICs on it.  One sits under another larger one.  Having a bit of trouble keeping my wits on this one.

Thanks!
Vince.


On 03/01/2018 12:23 PM, Michael Hagen wrote:
Vince,

I have been laying out PCBs for nearly 30 Years.  I have used just a
few.  They are really a learning curve.

There are some really expensive packages that I have not used
(Mentor?).  I would put little faith if they claim great auto-routing?

You might get results with an auto router, I never have.  I have watched
it put traces down until it gets in a corner.

Then it "Rips Up and tries again", kind of sadistic to watch!

If you had lots of space on the PCB, maybe let it go, and then  finish
it manually.

The real secret is to really spend time on a good schematic.  And when
the Design Check says "you got problems",

you better heed the warning and fix the problems.

73's

Mike, WA6ISP



On 3/1/2018 8:58 AM, Vince Vielhaber wrote:
Will any of these packages that have been mentioned do automatic
routing?  Or are you required to do all the runs manually?

Vince.



On 03/01/2018 10:12 AM, Michael Hagen wrote:
Lt Spice is a circuit simulator.  Not for Layout of PCBs.  Use one of
the online PCB programs folks have been discussing here on the group.
Look back through the posts on PCB Layout Software.  Any of them will
require a learning curve.

For instance, that circuit uses some small SCRs.  Not a real popular
part, you might get to make the Model (s).

There is a schematic model and its matching PCB model.  Start with the
schematic program and create a nice schematic before going to PCB.  It
will transfer its connections (netlist) to you PCB.   It will find many
mistakes (inconsistancies between schematic and layout).  If you are
real careful, you can make PCBs that are correct the first time!

PCB layout is Really Fun!  Better than crossword puzzles.

73's

Mike, WA6ISP


On 3/1/2018 4:33 AM, Walter wrote:
If I wranted to build a circuit like this one is there a software to
help me layout a perfboard for the circuit.  I have LTSpice but I
don't see anything to layout a perf board in it. It just may be that I
don't know where that feature is in the software.
--
73, W9KJO
Walter

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




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




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

Re: ubitx standoffs #parts

Dan Reynolds
 

Mike, would you share the STL files for your knobs? I've been printing knobs by the bucket loads and can't quite get any to fit the way I want.
--
Dan Reynolds -- KB9JLO
<><

Re: ubitx standoffs #parts

Michael Hagen
 

Yes, I have to look for the files.  I use 6-32 set screws.  You can clean out the holes, and heat up a long 6-32 bolt on the stove to tap them if you don't have a tap.   I spent days making knobs, so I have lots of files I need to look through.  Last year I switched to ABS because some of my parts melted in the car!

I finally made one for the small shafted volume too, after trying the shrink wrap trick.

It may take me a day.

73's

Mike, WA6ISP



On 3/1/2018 10:49 AM, Dan Reynolds wrote:
Mike, would you share the STL files for your knobs? I've been printing knobs by the bucket loads and can't quite get any to fit the way I want.
--
Dan Reynolds -- KB9JLO
<><

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

Re: TDA2822 ill treatment test!

Jerry Gaffke
 

Hmm, the TDA2822 does have a "bridge" mode where it is wired up with the two amps
out of phase to drive a speaker without needing output caps.
Is that what you are referring to?

The uBitx does not use bridge mode, the second section of the TDA2822 is left unused.
So the output load is between the amp output pin and ground,
allows the headphone jack to have the return at ground potential.
A DC blocking cap (C77 in the uBitx) is required.

> Shorting the output keeps both legs of it above ground.
Perhaps you mean that if we were in bridge mode with a 0 ohm load,
both sides of the load would wind up at a voltage above ground?

Jerry


On Thu, Mar 1, 2018 at 10:29 am, Dexter N Muir wrote:
Read the thread/s thoroughly, Raj (and all). Shorting the output keeps both legs of it above ground. It would seem that taking either leg to ground (that 'ring' connection that is taken there by a mono plug in particular) does the damage. It's the 'cheapo' method of boosting audio output: bi-phase two amps: 4x the power from the same supply voltage. This package evidently does this internally. If the spec sheet shows the internal circuit, this becomes obvious. I await reports...

Re: Second batch of uBITX shipping? #ubitx

Jay Davis
 

Mine was ordered around December 26th and I opened my door this morning to a DHL package .It has arrived,  I had not asked for DHL shipping but it came that way quite quickly.  I will send the 10$ shipping and am excited to go back over all the mods discussed and decide which ones to install.  Any one have suggestions on what mods to add since I am starting my build from scratch now. 
Thanks Jay .  N3QPW

Re: Second batch of uBITX shipping? #ubitx

Tim Young
 

Hi Jay:

This would be a great place to start

http://ubitx.net/ BITX Web Site of Mike ZL1AXG

Tim

WB7UVH



On 2018-03-01 12:08, Jay Davis wrote:

Mine was ordered around December 26th and I opened my door this morning to a DHL package .It has arrived,  I had not asked for DHL shipping but it came that way quite quickly.  I will send the 10$ shipping and am excited to go back over all the mods discussed and decide which ones to install.  Any one have suggestions on what mods to add since I am starting my build from scratch now. 
Thanks Jay .  N3QPW


Re: U1 fried

K4LXY
 

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

Re: full rig power control unit

Jerry Gaffke
 

Jerry didn't write the check, but that's in the ballpark for a fully loaded license.

I was encouraging them to look at other tools like Eagle, and later Kicad.
I like cheap, and would also prefer to not use anything stuck with MsWindows.
But folks there have a history of using PadsPCB going back to the 1980's,
and inertia is one of the elemental properties of the universe.

Jerry


On Thu, Mar 1, 2018 at 10:49 am, Michael Hagen wrote:

Jerry didn't not mention what the cost of Pads was, I bet over $10K.  And maybe another couple K PER YEAR to keep the license up.

 

uBITX - U1 Getting Fried - possible cause #ubitx

Jim Sheldon
 

Now that I've fried 2 of the TDA2822M's in my latest uBITX once while it was just sitting there and once when I plugged a speaker in, I took a good look at things.

My take is that huge 470 uF electrolytic in the output of the TDA2822M and the speaker gets a huge surge at turn on and during any loud noise or POP in the audio chain.  It will sit there just fine with nothing connected but the instant you plug a speaker in you cause that cap to discharge and recharge again causing a huge current spike and the TDA2822M can't handle it.

The current crop of 2822's do not have a recognizable manufacturer's logo on them and I suspect they are Chinese knockoffs.  I bought a handful of them off eBay from a seller called Teufel Tronics in the US and when the original blew, I replaced it with one of these.  It ran fine until I was working on loading some test software and turned it on with no speaker plugged in.  It was sitting there fat, dumb and happy until I plugged the speaker in.  All of a sudden, BANG and the top blew off the 2822.  Fortunately I have 8 of my stock left so if it goes again, it will be an easy fix.  I got smart and put an 8 pin socket in when I changed it this last time. 

It was suggested putting a 4 or 8 ohm resistor in series with the hot lead of the speaker and I intend to do this as soon as some get here from Digi-Key in a couple days.  That may limit the surge current enough to keep it from happening again.

Jim Sheldon W0EB

Re: U1 fried - LM38t works

K4LXY
 

I've taken Claude's suggestion with Jerry's addition, and I'm happy to say it works - lots of gain, too.  I haven't checked it extensively yet, but it's very promising.  When the TDA burnt up, I replaced it with a socket.  Then I used two more sockets to make a plug-in adapter, with Claude's pin-to-in guide and adding Jerry's suggestion of a .1 cap across pins 1 and 8.  Now I can get back to trying to solve the BCI problem....
Howard K4LXY

Re: uBITX - U1 Getting Fried - possible cause #ubitx

Jerry Gaffke
 

I think you're right.

The output pin has a quiescent DC voltage of around half the supply voltage, or about 6v,
so the 470uF cap will have a 6v charge on it when operating.  A significant bit of energy
for the TDA2822 to provide, and it tries to do so almost instantaneously in the case of a short.
A series resistor seems prudent. 

Perhaps the 470uF cap could be reduced to 100uF.
At 500hz the 100uF would have an impedance of 1/(2*pi*500*100e-6) = 3.18 ohms,
which seems borderline for good sound quality when using an 8 ohm speaker.

I vote for the resistor.  Something like 4 or 8 ohms, 1/2 Watt.
But worth experimenting if somebody has a stash of cheap TDA2822's on hand.

Configuring the TDA2822 for Dex's  bridge configuration does away with the cap charging problem,
but now the headphone jack has to be floating.  The bridge would be ideal for an internal speaker.

Jerry


On Thu, Mar 1, 2018 at 11:47 am, Jim Sheldon wrote:
My take is that huge 470 uF electrolytic in the output of the TDA2822M and the speaker gets a huge surge at turn on and during any loud noise or POP in the audio chain. 

Re: Raduino Connections #bitx40

James Wilson
 

Thanks,  Where do I get the sketch for the Bitx40?

Re: Raduino Connections #bitx40

Jerry Gaffke
 

Here's up to date firmware for the Bitx40
    https://github.com/amunters/

The "bitx40" branch will work with a stock bitx40 with no hardware mods,
probably best to get things working with that sketch first.
There are some optional hardware mods that enable some significant new features.

The "bitx40-raduino-v2" branch requires some minor hardware mods
and adds the flexibility of being able to vary the BFO frequency in firmware.
I'd recommend eventually moving to this firmware. 

Jerry


On Thu, Mar 1, 2018 at 12:18 pm, James Wilson wrote:
Thanks,  Where do I get the sketch for the Bitx40?

Re: U1 fried

Claude-Alain Baumgartner
 

Hi Howard,

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

Regards,
Claude

Re: U1 fried

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@...