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andrew kelley | 1 Feb 2006 01:33
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Re: [PIC] pics burn easily?

Try some 10uF on each side of the regulator and add a tiny cap(470pf)
across the PIC..  I'm not promising but I think that it will help. (it
fixed my problem on 12c508's glitching from opening shutting a
microwave door and other inductive kickback on the line)  We still
don't know how real the signals on the scope were however. (But it was
affecting the operation of the unit)

--
andrew

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Peter Todd | 1 Feb 2006 03:36
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Re: [OT]: agency approval for battery device?

On Tue, Jan 31, 2006 at 04:18:07PM -0700, Bob Axtell wrote:
> I've consulted for a few big companies, and I've seen how important it is.
> 
> One of my clients makes a gadget that allows the customer to virtually 
> "sign"
> their receipt during a financial transaction. I was there when a lady 
> from Chicago
> insisted that she was electrically "shocked" by the pen portion of the 
> device.
> Working with my client's lawyers, it made my job very simple when I was able
> to show how impossible that was, and could generate a rebuttal deposition
> based on their UL approval of the product. The lawsuit was bogus- and 
> everybody
> knew it- but juries hold UL/CE in very high regard, and facing that, the 
> lady
> decided to take her lawsuit elsewhere.

Very scary alright.

> On the other hand, I was at the Comdex trade show about 12 years ago 
> when the
> FCC went down the  aisles fining companies who were selling PC peripherals
> without FCC  Compliance Stickers. The FCC can be BAD NEWS.

Definetely, and I'm already pretty sure some of my art would fail FCC
tests. My 8^2 Automaton has 64 stepper motors and pic chips in it,
totally unshielded, with dozens of feet of equally unshielded wire
connecting up the i2c interface... Also add in an equal number of feet
of power runs, using a total of 40A max...
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John Waters | 1 Feb 2006 04:13
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[EE]: AC adapter spec lying

Hi All,

I have a small AC adapter, with the following spec. printed on a label 
attached to it:-
Class 2 Transformer
INPUT: 120V AC 60Hz
OUTPUT: 12V AC 200mA

I tested this AC adapter by connecting a 50 ohm resistor to the output and 
use an oscilloscope to read the output signal. I found that the signal is a 
sine wave at about 30V p-p. I then removed the resistor and read the output 
with NO load, the signal is a sine wave at about 40V p-p.

The spec. as marked on the adapter is "12V AC", how can we have an output 
that high? Is the manufacturer cheating? BTW, what is "Class 2 Transformer"?

Thanks in advance!

John

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Richard Prosser | 1 Feb 2006 04:36
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Re: [EE]: AC adapter spec lying

John,
40V pk-pk is equiv to 20V pk-0 which works out to about 14.4V rms. for
a sinewave.
So it's maybe a little high.

As an alternative - think of your 110V mains. This is 110V "rms" or
equivelent power to a 110V DC supply. So over a 1/2 cycle the power
would be the same. Therefore the peak voltage for a sinewave would be
sqrt(2)*110 = 155.5V. Peak-peak is twice this or 310V.

RP

On 01/02/06, John Waters <john_fm_waters@...> wrote:
> Hi All,
>
> I have a small AC adapter, with the following spec. printed on a label
> attached to it:-
> Class 2 Transformer
> INPUT: 120V AC 60Hz
> OUTPUT: 12V AC 200mA
>
> I tested this AC adapter by connecting a 50 ohm resistor to the output and
> use an oscilloscope to read the output signal. I found that the signal is a
> sine wave at about 30V p-p. I then removed the resistor and read the output
> with NO load, the signal is a sine wave at about 40V p-p.
>
> The spec. as marked on the adapter is "12V AC", how can we have an output
> that high? Is the manufacturer cheating? BTW, what is "Class 2 Transformer"?
>
> Thanks in advance!
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Herbert Graf | 1 Feb 2006 04:49

Re: [EE]: AC adapter spec lying

On Tue, 2006-01-31 at 19:13 -0800, John Waters wrote:
> Hi All,
> 
> I have a small AC adapter, with the following spec. printed on a label 
> attached to it:-
> Class 2 Transformer
> INPUT: 120V AC 60Hz
> OUTPUT: 12V AC 200mA
> 
> I tested this AC adapter by connecting a 50 ohm resistor to the output and 
> use an oscilloscope to read the output signal. I found that the signal is a 
> sine wave at about 30V p-p. I then removed the resistor and read the output 
> with NO load, the signal is a sine wave at about 40V p-p.
> 
> The spec. as marked on the adapter is "12V AC", how can we have an output 
> that high? Is the manufacturer cheating? BTW, what is "Class 2 Transformer"?

Sounds about right.

Remember, when dealing with AC there are SEVERAL ways of measuring
things. The 12V speced is the RMS voltage. 

For a pure sine way the RMS voltage is the peak voltage divided by the
square root of two.

The peak voltage is half the peak to peak voltage.

So, 12V RMS -> 12*1.41 = 16.92V Peak -> 16.92*2 = 33.82V Peak to Peak.

So, your adapter is pretty close to spec, as can be expected with that
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Bob Axtell | 1 Feb 2006 08:40
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Re: [OT]: agency approval for battery device?

Peter Todd wrote:

<respectful snip>

>
>So under what circumstances must a product be FCC complient? Are there
>minimum volume/sales exemptions of an kind?
>
>  
>
What falls under the compliance requirement is spelled out under the FCC 
website
(or used to be). Certain equipment is exempt, such as some medical 
equipment, test
equipment, and yes - even certain commercial motor controllers.

Yes, it makes it hard on the little guy. But we can't have somebody's 
widget interfering
with airplane approach beacons, can we? That's EXACTLY what it is for. 
That's what
the FCC does.

--Bob

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Note: To protect our network,
attachments must be sent to
attach@... .
1-520-850-1673 USA/Canada
http://beam.to/azengineer
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Bob Axtell | 1 Feb 2006 08:52
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Re: [EE]: AC adapter spec lying

Herb explains it perfectly. The 50 ohm resistor loaded the output and
it dropped appropriately.  Adjust that resistor until you measure 200mA
of AC current through it, and the output from the transformer will
measure 12VAC RMS.

Incidentally, did you know that the way transformers are now made  has not
changed appreciably from the way Nikola Tesla designed them in 1890?

--Bob

Herbert Graf wrote:

>On Tue, 2006-01-31 at 19:13 -0800, John Waters wrote:
>  
>
>>Hi All,
>>
>>I have a small AC adapter, with the following spec. printed on a label 
>>attached to it:-
>>Class 2 Transformer
>>INPUT: 120V AC 60Hz
>>OUTPUT: 12V AC 200mA
>>
>>I tested this AC adapter by connecting a 50 ohm resistor to the output and 
>>use an oscilloscope to read the output signal. I found that the signal is a 
>>sine wave at about 30V p-p. I then removed the resistor and read the output 
>>with NO load, the signal is a sine wave at about 40V p-p.
>>
>>The spec. as marked on the adapter is "12V AC", how can we have an output 
>>that high? Is the manufacturer cheating? BTW, what is "Class 2 Transformer"?
(Continue reading)

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Rob Hamerling | 1 Feb 2006 09:31
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Re: [PIC] EEPROM info in the HEX file and Wisp628/XWisp2.


Hi Jan-Erik,

Jan-Erik Soderholm wrote:
> Rob Hamerling wrote :
> 
>>Unfortunately I don't have a 16F628A on hand, but I have no problem 
>>program EEPROM memory of a 16F627 and a 16F648A (the closest 
>>members of  the family I have) with a Wisp628 and Xwisp2.
> 
> 
> OK, tested with a 648A, and it worked first try !

The 'Programming Specifications' mention no procedural differences 
between 16F627A, 628A and 648A!

>>The log may show something, but I'm afraid not. Nevertheless 
>>please make one and send it to me.
> 
> 
> It's not clear to me how to create that file.
> I tried "LOG file", but just got one line with "break"
> something. Any tip ?

Don't know what your commandline looked like, but when it specifies only 
'log file' then there is nothing to log! Specify something like:

   xwisp2w log file go 16f628a.hex

> Also, I've used both the original 1.09 firmware and
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Jinx | 1 Feb 2006 09:32
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Re: [EE]: AC adapter spec lying

> Adjust that resistor until you measure 200mA of AC current
> through it, and the output from the transformer will measure
> 12VAC RMS

I bought a pile that are "12VDC 200mA". They are actually
about 21VDC unloaded and my circuit needs to have a load
resistor (470R) across the supply to take the sting out of it.
It does put out the advertised 12VDC (ripply, believe it or
not) at 200mA, which is what is wanted for driving an electric
bell, and relay

A plugpack is something you should ALWAYS ALWAYS
measure before you use it as a supply, especially if it's unregulated.

"6VDC 500mA" might be 10V or more unloaded and you could
do a lot of damage to a circuit that loads it too lightly. Add to the
label if you want to, for future reference. One day you might need
a 10V 50mA and that 6V 500mA could be it

Labels on unregulated plugpacks are at best sloppy and misleading
if you don't know that the stated output voltage is generally at about
the stated drain. If you're lucky and the manufacturer isn't too over-
enthusiastic about the capabilities of his product

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Jan-Erik Soderholm | 1 Feb 2006 10:36
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RE: [PIC] EEPROM info in the HEX file and Wisp628/XWisp2.

Rob Hamerling wrote :

> Don't know what your commandline looked like, but when it 
> specifies only 
> 'log file' then there is nothing to log! Specify something like:
> 
>    xwisp2w log file go 16f628a.hex

Sorry, I had both "port 5" and "go myfile" in the cmd line.
Anyway...

> > So there is some difference here between how XWisp.py
> > and XWisp2 handles this.
> 
> The protocols are (at least should be) identical, but the 
> timings may be different. Have a look in the xwisp2_14.cfg file
>  For the 16F628A you'll find a specification  'Delay = 50'.

No, it sad "'Delay = 40' for the 628A....
(from the 1.8.2 kit downloaded yesterday evening)

The *648A*  had "= 50".

With = 50 for the 628A it also works fine.

Thanks for the fast aupport !
Jan-Erik.

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Gmane