Re: Need Circuit Design -- Cheap...

On Sun, 26 Apr 2009 20:54:29 -0400, Bob Thomas <bobtms@xxxxxxxxxxxx>
wrote:

<snip>
Why are you using "CD" parts, go modern with "74HCxxxx"

"Tiny Ckts" are available in many small-gate-count types.

When I looked up the parts at Digi-Key there were a lot of nubmering
methods, none had any that just started with "74HCxxxx"

MM74HC02N-ND
MM74HC02N

TC74HC02AP-ND
MM74HC02N

SN74HC02N-ND
SN74HC02N

CD74HC02E
etc...

First 2 letters appear to be just the manufacturer, though "CD", in
the past, suggested voltage capability higher than 5V.

MM=Motorola
SN=TI


http://search.digikey.com/scripts/DkSearch/dksus.dll?Selection

I don't seem to find the difference between them, I am getting DIP
Through Hole, after that all I care is that they work.

Any usggestions, or is there a better place to go? I like Digi-Key
even though I generally pay more than like Goldmine, but I can usually
get every part I need from one place and the cost difference is
generally very small compared to shipping charges from 5 places, not
to mention my time.

I am very sorry to hear about your son, my Step mom, all 4
grandparents, well you get the idea,I will make the donation in his
name.

Thanks


On Sun, 26 Apr 2009 11:24:05 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@xxxxxxxxxxxxxxx> wrote:

On Sun, 26 Apr 2009 14:08:09 -0400, Bob Thomas <bobtms@xxxxxxxxxxxx>
wrote:

Jim,
I have redrawn your circuit with the actual physical parts and
added the relay driver you suggested, I will also follow your advice
on the other part substitutions to work out the kinks and study the
data ***, again as you suggested.

So now I am down to 2 questions, the latter I can really just try on
my own, but while I have your ear:

1. Can you please look at the schematic I have drawn from your
schematic and let me know if it looks right? I think I have all of the
connections to the right pins/parts.

http://people.delphiforums.com/wildbill47/X10/New_Alm_Ctrl.jpg

I've revised it about 15 minutes ago, saves one package of parts; and
adds the ability to cope with duty-cycle effects.


2. I noticed when I was on Digi-Key looking specifically at the
CD74HC002E and the CD74HC00E that they had parts that just had one
gate in them, a lot smaller, the only two differences I noticed is
they did not have the "HC" in the part number, and the mA was 32mA
instead of 5mA, the input voltage / output voltage all were the same,
can I use these smaller parts or should I use the exact ones you
specified. The CD74HC04E also comes in a 2 gate model, same deal on
the specs, all the same but the "HC" and the mA was higher.

Why are you using "CD" parts, go modern with "74HCxxxx"

"Tiny Ckts" are available in many small-gate-count types.


I will put together the order today with the exact parts as well as
the others, but just wondered if it would make a difference, they were
all so inexpensive anyway my only interest was on saving space.

Again I really appreciate your help and as soon as it works there will
be a check off to the American Cancer Society, which already happens
to be one of my main charities, but I will donate it in your name.

Donate in the name of Duane Lee Thompson, my youngest son, who died at
age 33, from colon cancer. Thanks!


Are you sure you don't want something for you own time, patience, and
talent?

Nope. It was just for fun, something to exercise my brain while I was
puzzling over an odd effect in an I/C chip design.


Thanks!

PS -- This is the kind of experience I remember from
sci.electronics.design, I am glad it is not dead. There was a day when
I was much more able to be a contributor than just a "taker", but when
this works I will share it with my fellow X-10 hobbyists and credit
you!

Enjoy!


On Sun, 26 Apr 2009 08:12:50 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@xxxxxxxxxxxxxxx> wrote:

On Sun, 26 Apr 2009 01:57:53 -0400, Bob Thomas <bobtms@xxxxxxxxxxxx>
wrote:

Hi Jim,
From the timing chart on page 2 of the PDF this looks
PERFECT!!!! Now if I may ask just a few, perhaps dumb questions?

1 - I take it I should tap in to my circuit between the uC and the LED
where I found the clean 0VDC and 5VDC?

Yes.


2 - What is the part labeled D2A1? Is that the LED in my Alarm System?

Parts DSTM1 and D2A1 are simulation elements. (So I could use a
digital table to represent your incoming waveform.)

The actual circuit begins at the input to inverter 74HC04. Connect
your logic signal here.


3 - What are the points with V in a circle? Do those just correspond
to the the measurements on the second page of the PDF?

Those are called "markers" and DO corresponds to the measurement shown
on the waveforms page.


4. Would the relay I use still be be the Hamlin HE721A0500 wired as
such: (5DVC Coil voltage)

U4A---------+--------+
| |K
Relay Coil ---
| ^
| |
GND GND

U5A---------+--------+
| |K
Relay Coil ---
| ^
| |
GND GND

What are the current requirements for those relays?

I'd probably buffer with an NPN, like this...


+5V
o
|
+-------+
| |
) |
( ---
RELAY COIL ---> ) / \ DIODE
( ---
| |
| |
+------+
|
|
4.7K | /
|/
RELAYSIG o--/\/\/\/----| 2N3904
|\
| \>>
|
|
|
GND


5. If the flash rate is not 50% what are the parts that would need
tweeking. Would that be C1 and C4? If so is there a formula I can use
to determine the correct values, or just play with it until it is
right?

Voltage at point "TT1" is the average of the blinking voltage. At 50%
duty cycle it will be +2.5V (with some ripple). If the duty cycle is
like 60/40, I'll have to add some resistor/diode gimmicks to keep TT1
centered.


6. I noticed that C1 is an electrolytic and C4 is shown as not, should
they both be electrolytics, they seem to be configured the same way in
the schematic, hooked to the Threshold pin on the LM555C

If you can get C1/1uF as non-electrolytic, do it.


7. Whar exactly does your reference 1/3 - 2/3 mean, did you mean
between the 2 LM555C's as in U1/Pin 3 and U3/Pin 3?

555 Trip points are at 1/3 and 2/3 of supply. Grab a data *** and
learn about it.


8. For all the caps that are not electrolytics, are ceramics good or
should I use something other type.

Ceramic are best, if available.


9. Are 20% tolerance on the resistors ok or should I go for tighter,
1% / 5% etc?

Your biggest issue may be capacitor tolerances. R1 and R2 might be
better as 1 1Meg pot plus a 510K resistor.


That circuit looks so clean and simple, I can't wait to order the
parts and try this out.

Many thanks for this, I will try to get the parts ASAP and breadboard
this by next weekend.

I will let you know the results as soon as I get it wired!

Again, many thanks!!

You are quite welcome.

Payment? In your original post you mentioned payment. When you are
happy with the circuit, please make an appropriate donation to the
American Cancer Society. Thanks!



On Sat, 25 Apr 2009 17:11:43 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@xxxxxxxxxxxxxxx> wrote:

On Fri, 24 Apr 2009 21:45:10 -0400, Bob Thomas <bobtms@xxxxxxxxxxxx>
wrote:

Hi Jim,
This time I think I have the details together a little better,
and have included three links to the relevent parts, at least I hope
so, it took a few of those questions to see I needed to give better
details to get a better answer, I think I have those now, so here it
is:

[snip]

Try....

www.analog-innovations.com/SED/AlarmController.pdf

CAUTION: If the flash rate isn't approximately 50%-50% some tweaks
may be necessary to keep the ripple inside the 1/3 - 2/3 trip points
of the LM555C.

...Jim Thompson


On Sat, 25 Apr 2009 17:11:43 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@xxxxxxxxxxxxxxx> wrote:

On Fri, 24 Apr 2009 21:45:10 -0400, Bob Thomas <bobtms@xxxxxxxxxxxx>
wrote:

Hi Jim,
This time I think I have the details together a little better,
and have included three links to the relevent parts, at least I hope
so, it took a few of those questions to see I needed to give better
details to get a better answer, I think I have those now, so here it
is:

[snip]

Try....

www.analog-innovations.com/SED/AlarmController.pdf

CAUTION: If the flash rate isn't approximately 50%-50% some tweaks
may be necessary to keep the ripple inside the 1/3 - 2/3 trip points
of the LM555C.

...Jim Thompson

...Jim Thompson

...Jim Thompson

...Jim Thompson
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