Chip with simple program for Toy

[matt]

On Wed, 22 Feb 2006 16:37:33 +0100, "petrus bitbyter"
<pieterkraltlaatditweg@enditookhccnet.nl> wrote:

So the equations would then be converted back to a JEDEC file?



Sure, but JEDECs differ widely for different components. They often even
differ for the same component type but other manufacturer.

Really? Ugh - confusing!

As for the speed itself I shouldn't expect problems. According to the
Philips datasheet the standard N82S153 is rated for 40ns, the N82S153A is
rated for 30ns. So your 25ns GAL may be too fast rather then too slow. But
in that case I consider it either a poor design or the use of some special
trick. Which will not help you, I'm afraid.

:-((

BTW It worked for someone else. Do you mean same board,

Same board, yup (well, same design, same manufacturer, etc).

same 82S153 content
and same object GAL? (So same type and brand?)

Same GAL type: GAL16V8D - not sure what speed or brand he used though
as he's not replying to his emails.

Any idea what the GAL is
supposed to do?

I'll quote from the chap who came up with the JEDEC:

"All ROM and RAM on this Memory Board is initially decoded by the
82s153 FPLA at location U10. The FPLA enables address decoders based
on the upper 3 address bits of the address bus. Additionally, the FPLA
prevents ROM and RAM access during certain system processes including:
refresh cycles, active resets, I/O requests and a architecture
specific signal called /BUZOFF. The FPLA contains 5 address inputs and
7 status line inputs. Outputs of the FPLA are 4 decoder enable lines
and 1 transceiver direction select line. The enable line for ROMs X1
through X4 (74LS139 at U8, pin 1) is selected on addresses x0000-x3fff
( !a15, !a14). The 4 ROMs are then selected off of a13 and a 12 by the
lower half of the 139 decoder at U8. All the other selects work
similarly. The second half of U8 (pin 15, enable) selects ROMs X5-X8
(a15, !a14), the lower half of U9 (pin 1, enable) selects the ROMs at
X9 and X10 (a15, a14, !a13)and the upper half of U9 (pin 15 enable)
selects one of the 4 RAMs (a15, a14, a13) based on address lines a11
and a12).

The FPLA also selects the direction of the 74ls245 transceiver at U17.
On a write, pin 1 of U17 is held high to allow data to flow from the
processor data bus to the RAM/ROM board data bus, on a read the line
is held low and the data flows in the opposite direction. Most of the
additional circuitry on the ROM board deals with selecting the RAM at
X21 for high score and setup information. The three 74ls244s at U16,
U15 and U 11 are all used as line drivers with all of their select
lines tied low permanently.

The original FPLA used is a Signetics 82s153, which is now obsolete, a
modern replacement is a Signetics pls153, however I have not been able
to get a good copy of one so I had to write a replacement using a PLD
(GAL16V8D)."

Any problem posting the JEDEC(s) you have?

Here it is from the guy's site:

http://web.archive.org/web/20020331203553/http://my.erinet.com/~jamesm/tech/roto/roto.jed

(Part of) the
schematic?

I don't know how to extract a page or two from a PDF, but the whole
manual (12 MBytes! with schems at the end) can be found in this file:

http://arcarc.xmission.com/PDF%20Arcade%20Manuals%20and%20Schematics/Robby%20Roto.pdf

you'll need to look at the for the 'Memory Board'. The device in
question is the PLS at location U10

BTW, the quality of the schems is poor in places, but just about
readable.


Many thanks.

 

[Michael A. Terrell]

Pooh Bear wrote:

joshua wrote:

Hi All,
what is the meaning of 24bit,16 bit in Analog to Digital converter.
I think it is for resolution. I am not understood properrly any one
help me.

It is indeed resolution.

For someone supposedly involved in electronic design you don't know
very much do you ?

Graham

For someone posting on the basics newsgroup you are rather rude. If
you don't want to help someone, don't make fun of them. this isn't SED,
and the OP isn't claiming to be an EE, so get over yourself.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[John Popelish]

ErikBaluba wrote:

I do understand how an inductor behaves but as often happens I got confused
about the terminology. So the self-induction part is not referring to a
special kind of diode, but rather to a specific use of a diode, meaning
recuperating self-induction from a inductive load, in this case the motor.

That is my guess.

But what would really happen if the diodes weren't there?

The inductive load will produce whatever voltage it takes to get the
inductive current to go somewhere, either into driver breakdown
voltage losses or into the stray capacitance of the winding and driver
devices. The voltage across an inductor is proportional to the
inductance and the rate of change of current. In order to have the
current go from some finite value to zero in zero time (an infinite
rate of change of current) requires that there be an infinite voltage
across the inductance. That never happens, because something else
happens, first.

Assuming that the
output ports on the 298 driver do not zink any current caused by
self-induction in the motor, without the diodes would the self-induction be
dissipated in the motor's coil-windings?

No. More likely in the eddy current losses of the iron parts of the
motor (they are just shorted secondaries inside the windings) and in
the switching devices trying to turn off.

Also, are the diodes there to also
protect the outputs of the 298 driver IC from spikes caused by
self-induction in the motor?

Definitely. Putting the energy back into the supply is just a bonus.

 

[Chris]

PeteS wrote:

Chris wrote:
joshua wrote:
Hi All,
what is the meaning of 24bit,16 bit in Analog to Digital converter.
I think it is for resolution. I am not understood properrly any one
help me.
Kind Regards,
Joshua

Hi, Joshua. May I suggest that you find a tutor, and pay him to help
you with your school project.

You are in way over your head, and a newsgroup is not the appropriate
place to get the kind of timely, intensive help you apparently need.
This newsgroup is also not an appropriate place for homework questions.

I'm sure you could either place a post on your school bulletin board,
or advertise to find an upperclassman who is willing to be employed.

Good luck
Chris

To a certain extent I agree, yet the OP has chosen s.e.b. (rather than
s.e.d. at least) and at least has asked a question (albeit not using
particularly precise grammar and perhaps even wishes to learn - who
knows.

I always thought s.e.b. might be the appropriate place for someone to
ask a question on an electronics subject about which they have no
knowledge, especially if they admit to not knowing

Cheers

PeteS

Hi, Pete. You're right, of course. A few people have said the
unofficial motto of s.e.b. should be that "There's no question too
basic for this newsgroup". We don't want to scare off the newbies.

Look at his 15 topic posts over the last two weeks in s.e.b., s.e.d.
and sci.electronics.components, and judge for yourself. Look
particularly at the posts relating to his weigh scale project, load
cells and the LCD display. I'm thinking in particular about his post
early this morning in s.e.d. "Hi, All (Load Cell)", and the several
following spam posts, "please help me".

He really needs much more help than the advice he can get here, and
he's not being fair to himself looking for that help in newsgroups.
His project will never get done by the end of the semester. And
incidentally, I've heard it expressed a few times here that the
function of homework and class projects is to reinforce learning, and
we're defeating that purpose by serving up answers to homework
questions.

Joshua is apparently in so far over his head that a good answer to his
question might not even help. If he does understand anything about
digital logic and counting, he doesn't indicate it. And if he did, the
most appropriate response here would actually be to have somebody find
out what Digital Logic textbook they're using in his class, obtaining
the book, then typing up the chapter on ADCs in a post (including
illustrations in ASCII art ;-). He really should just read it himself,
and purchase the textbook if he hasn't done so. Sometimes there are no
shortcuts to learning -- you just have to do it. We did.

Every college and technical school has sharp kids who are looking for a
few extra honest coins (I would have included myself among those back
in the day). It might be better for him to just find one, and get some
tutoring and/or design help with his project. If he doesn't understand
the classwork, several hours a week of one-on-one intensive help might
get him on track quickly without a whole lot of expense.

I do like the fact that nobody's flaming him here, including me. I
wish Joshua well, and hope he gets all the help he needs.

Cheers
Chris

 

[Rich Grise]

On Wed, 22 Feb 2006 17:02:46 +0000, matt wrote:

I don't know how to extract a page or two from a PDF, but the whole
manual (12 MBytes! with schems at the end) can be found in this file:

You can draw a box around it, copy it to the clipboard, and paste it into
a paint program and save it as a .gif, then link to _that_.

Good Luck!
Rich

 

[Rich Grise]

On Wed, 22 Feb 2006 11:02:40 +0000, matt wrote:

The board is okay as it works with the original 82S153 (which I can't
dump and don't have a replacement for - I'm testing the GAL on this
board but it will be going on another board (same type) as that one
has a bad 82S153).

Can't dump it? Can't you plug it into a breadboard, put a counter on
the inputs, and see what you get at the outputs?

Then you would at least have a truth table, unless it's got some kind
of embedded state machine or something. It'd also help to know if
the outputs are latched or anything. Is there a data sheet anywhere
on the 82S153?

Good Luck!
Rich

 

[Rich Grise]

On Tue, 21 Feb 2006 08:08:57 -0800, joshua wrote:

i need a perfect 4 digit Lcd driver with display datasheet anyone know
the datasheet part no plz help me.

Google is your friend:
http://www.google.com
and put stuff like "LCD" or "LCD Display" or "LCD Display driver" in the
search box - poke around a bit!

http://folk.ntnu.no/shane/stasj/pics/humor/div/128.html ;-)

Cheers!
Rich

 

[matt]

On Wed, 22 Feb 2006 18:11:50 GMT, Rich Grise <richgrise@example.net>
wrote:

Can't dump it? Can't you plug it into a breadboard, put a counter on
the inputs, and see what you get at the outputs?

Only if I knew exactly what I was doing.

Then you would at least have a truth table, unless it's got some kind
of embedded state machine or something. It'd also help to know if
the outputs are latched or anything. Is there a data sheet anywhere
on the 82S153?

There's one here:

http://www.datasheetarchive.com/search.php?q=82s153&sType=part&ExactDS=Starts


Thanks for your help!

 

[matt]

On Wed, 22 Feb 2006 18:00:12 GMT, Rich Grise <richgrise@example.net>
wrote:

On Wed, 22 Feb 2006 17:02:46 +0000, matt wrote:

I don't know how to extract a page or two from a PDF, but the whole
manual (12 MBytes! with schems at the end) can be found in this file:

You can draw a box around it, copy it to the clipboard, and paste it into
a paint program and save it as a .gif, then link to _that_.

Good point but I have no webspace - where would I upload it to?

 

[Sambo]

Ben Jackson wrote:

On 2006-02-21, matt <mattgyma@hotmail.com> wrote:

Something to do with the type of GAL or perhaps even the speed?


If the edge rate of the new GAL is too fast you could try putting 100
ohms or so inline with the new chip (build a small daughter card, perhaps).

But since you say it works for someone else, perhaps most likely is
that some other part of your 25 year old board is bad.

LOL, rotorooter? Let us know when you are fixing at least burger time hehe.



The most suspicious signal is the last (bottom) output controlling the U17
as someone suggested, resistor may work. Two transistor driver ( optionally with RC on input ) or run all outputs through 74L244 (L only, if it exists) although that only adds about 12ns, 'L' would probably be about 20ns.
I'd try the following, adding R1( and C1 only if needed, start in center position and reduce.




+5V ----------------------
| |
R1 |-| -
-------- 2.2K | | 510-1K | |
from PLA 13 ----| 1K |----| | | | |
-------- | T T
^ | 2.2K | |
| | --------- |/ ----- |/-----PPLA 13 socket
-------*-----| |----| |-------|
| --------- |\ |\
C1 | V V
100pf ===== | 2x2n4401 |
===== | |
| | |
| ===== =====
| === ===
=====
===

Or if using R1 C1 drop the second transistor with its resistor , put 1-1.5 K resistors
between collector and +5 and emitter and GND and take the signal from the emitter. However, this may not be a good idea for a digital circuit (slow rise time).


Now fire up that slow comp and it is time for a little Major Havoc, hehe.

Cheers.

 

Why not just use datasheets.org.uk or datasheetarchive.com description
search.

http://www.datasheets.org.uk/search.php?q=LCD+Display+driver+digit&sType=desc&ExactDS=Starts

 

[matt]

On Wed, 22 Feb 2006 15:38:25 -0500, Sambo <sambo@void.com> wrote:

LOL, rotorooter?

Close - Robby roto in fact.

Let us know when you are fixing at least burger time hehe.

)

The most suspicious signal is the last (bottom) output controlling the U17
as someone suggested, resistor may work. Two transistor driver ( optionally with RC on input ) or run all outputs through 74L244 (L only, if it exists) although that only adds about 12ns, 'L' would probably be about 20ns.
I'd try the following, adding R1( and C1 only if needed, start in center position and reduce.

<snip>

Excellent, thanks - I'll make that up and let you know how it goes.



Cheers.

 

[petrus bitbyter]

"matt" <mattgyma@hotmail.com> schreef in bericht
news:43fc9766.435973578@news.freeserve.net...

On Wed, 22 Feb 2006 16:37:33 +0100, "petrus bitbyter"
pieterkraltlaatditweg@enditookhccnet.nl> wrote:


So the equations would then be converted back to a JEDEC file?



Sure, but JEDECs differ widely for different components. They often even
differ for the same component type but other manufacturer.

Really? Ugh - confusing!

As for the speed itself I shouldn't expect problems. According to the
Philips datasheet the standard N82S153 is rated for 40ns, the N82S153A is
rated for 30ns. So your 25ns GAL may be too fast rather then too slow. But
in that case I consider it either a poor design or the use of some special
trick. Which will not help you, I'm afraid.

:-((

BTW It worked for someone else. Do you mean same board,

Same board, yup (well, same design, same manufacturer, etc).

same 82S153 content
and same object GAL? (So same type and brand?)

Same GAL type: GAL16V8D - not sure what speed or brand he used though
as he's not replying to his emails.

Any idea what the GAL is
supposed to do?

I'll quote from the chap who came up with the JEDEC:

"All ROM and RAM on this Memory Board is initially decoded by the
82s153 FPLA at location U10. The FPLA enables address decoders based
on the upper 3 address bits of the address bus. Additionally, the FPLA
prevents ROM and RAM access during certain system processes including:
refresh cycles, active resets, I/O requests and a architecture
specific signal called /BUZOFF. The FPLA contains 5 address inputs and
7 status line inputs. Outputs of the FPLA are 4 decoder enable lines
and 1 transceiver direction select line. The enable line for ROMs X1
through X4 (74LS139 at U8, pin 1) is selected on addresses x0000-x3fff
( !a15, !a14). The 4 ROMs are then selected off of a13 and a 12 by the
lower half of the 139 decoder at U8. All the other selects work
similarly. The second half of U8 (pin 15, enable) selects ROMs X5-X8
(a15, !a14), the lower half of U9 (pin 1, enable) selects the ROMs at
X9 and X10 (a15, a14, !a13)and the upper half of U9 (pin 15 enable)
selects one of the 4 RAMs (a15, a14, a13) based on address lines a11
and a12).

The FPLA also selects the direction of the 74ls245 transceiver at U17.
On a write, pin 1 of U17 is held high to allow data to flow from the
processor data bus to the RAM/ROM board data bus, on a read the line
is held low and the data flows in the opposite direction. Most of the
additional circuitry on the ROM board deals with selecting the RAM at
X21 for high score and setup information. The three 74ls244s at U16,
U15 and U 11 are all used as line drivers with all of their select
lines tied low permanently.

The original FPLA used is a Signetics 82s153, which is now obsolete, a
modern replacement is a Signetics pls153, however I have not been able
to get a good copy of one so I had to write a replacement using a PLD
(GAL16V8D)."

Any problem posting the JEDEC(s) you have?

Here it is from the guy's site:

http://web.archive.org/web/20020331203553/http://my.erinet.com/~jamesm/tech/roto/roto.jed

(Part of) the
schematic?

I don't know how to extract a page or two from a PDF, but the whole
manual (12 MBytes! with schems at the end) can be found in this file:

http://arcarc.xmission.com/PDF%20Arcade%20Manuals%20and%20Schematics/Robby%20Roto.pdf

you'll need to look at the for the 'Memory Board'. The device in
question is the PLS at location U10

BTW, the quality of the schems is poor in places, but just about
readable.


Many thanks.

I'm really puzzled. Had a look at the schematics. The device is supposed to
do straight forward address decoding. No latches, no tricks no reason to
think the GAL to be too fast. Had a look at the JEDEC as well. Did not check
it out up to the last bit but as far as I can see it is programmed to do
what the GAL guy said. What's more, a correctly programmed GAL should be
pin-compatible with the original 82S153. There's only one nasty possibillity
I can think about: there have been GALs on the market that did not meet the
full specs due to a mask fault. The company made new masks and sold the old
ones to another firm that used them to made there own GALs, including the
flaw. I never had a problem myself so it's only hearsay. Besides I'm not
sure the D-types were effected, but you may have run into this old problem.

You can make some hardware to compare the 82S153 and the GAL16V8D. An EPP
printerport, some LS364 latches and a LS245 buffer on a breadboard is all
you need. Feed the DUT with a counter, read back all outputs and save the
results on disk. Read the next device and compare the results.

Can't you find someone with a programmer that can read the old 82S153? It's
only combinatotial logic and FAIK they had no security bit. Somewhere I
still should have the software to make equationfiles from the JEDEC. It's
easier then building hardware.

petrus bitbyter

 

[Jamie]

joshua wrote:

Hi All,
what is the meaning of 24bit,16 bit in Analog to Digital converter.
I think it is for resolution. I am not understood properrly any one
help me.
Kind Regards,
Joshua

you are correct, its basicly how

accurate you can decode an analog
signal.
results of the lowest and highest
value would most likely be the same
as lower bit converters how ever,
each reading you get is of larger
scale number between the same range
as that of the lower bit converters.
for example..
an 8 bit coverter has a range of
0..255 , 0 = 0 volts, 255 = 10 volts for example.
a 16 bit converter has a range of
0..65535, 0 = 0 volts, 65535 = 10 volts...

you can see here that between the low and
high you can get more accurate readings.
now sampling rates is still another story.


--
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

 

[PeteS]

Chris wrote:

PeteS wrote:
Chris wrote:
joshua wrote:
Hi All,
what is the meaning of 24bit,16 bit in Analog to Digital converter.
I think it is for resolution. I am not understood properrly any one
help me.
Kind Regards,
Joshua

Hi, Joshua. May I suggest that you find a tutor, and pay him to help
you with your school project.

You are in way over your head, and a newsgroup is not the appropriate
place to get the kind of timely, intensive help you apparently need.
This newsgroup is also not an appropriate place for homework questions.

I'm sure you could either place a post on your school bulletin board,
or advertise to find an upperclassman who is willing to be employed.

Good luck
Chris

To a certain extent I agree, yet the OP has chosen s.e.b. (rather than
s.e.d. at least) and at least has asked a question (albeit not using
particularly precise grammar and perhaps even wishes to learn - who
knows.

I always thought s.e.b. might be the appropriate place for someone to
ask a question on an electronics subject about which they have no
knowledge, especially if they admit to not knowing

Cheers

PeteS

Hi, Pete. You're right, of course. A few people have said the
unofficial motto of s.e.b. should be that "There's no question too
basic for this newsgroup". We don't want to scare off the newbies.

Look at his 15 topic posts over the last two weeks in s.e.b., s.e.d.
and sci.electronics.components, and judge for yourself. Look
particularly at the posts relating to his weigh scale project, load
cells and the LCD display. I'm thinking in particular about his post
early this morning in s.e.d. "Hi, All (Load Cell)", and the several
following spam posts, "please help me".

He really needs much more help than the advice he can get here, and
he's not being fair to himself looking for that help in newsgroups.
His project will never get done by the end of the semester. And
incidentally, I've heard it expressed a few times here that the
function of homework and class projects is to reinforce learning, and
we're defeating that purpose by serving up answers to homework
questions.

Joshua is apparently in so far over his head that a good answer to his
question might not even help. If he does understand anything about
digital logic and counting, he doesn't indicate it. And if he did, the
most appropriate response here would actually be to have somebody find
out what Digital Logic textbook they're using in his class, obtaining
the book, then typing up the chapter on ADCs in a post (including
illustrations in ASCII art ;-). He really should just read it himself,
and purchase the textbook if he hasn't done so. Sometimes there are no
shortcuts to learning -- you just have to do it. We did.

Every college and technical school has sharp kids who are looking for a
few extra honest coins (I would have included myself among those back
in the day). It might be better for him to just find one, and get some
tutoring and/or design help with his project. If he doesn't understand
the classwork, several hours a week of one-on-one intensive help might
get him on track quickly without a whole lot of expense.

I do like the fact that nobody's flaming him here, including me. I
wish Joshua well, and hope he gets all the help he needs.

Cheers
Chris

Well, there are some who seem to continue to ask questions on
'advanced' things without asking for basics first , although that (for
a few posts anyway) is perhaps understandable - they don't know there
are basics underlying the question.

After a few such posts, provided we've explained that the OP might like
to ask very basic questions where we could even point to a resource on
said basics, it does tend to get old.

That said, I didn't see the posts in question (I was netless for a
while on a job - aarrgghh) so I don't know this particular history

I think I get more pee'd at poor grammar and spelling than apparently
silly questions - after all, if I can't understand the question,
there's little hope of answering it !

I don't doubt you had no intention to flame

Cheers

PeteS

 

[matt]

On Wed, 22 Feb 2006 23:02:50 +0100, "petrus bitbyter"
<pieterkraltlaatditweg@enditookhccnet.nl> wrote:

I'm really puzzled. Had a look at the schematics. The device is supposed to
do straight forward address decoding. No latches, no tricks no reason to
think the GAL to be too fast. Had a look at the JEDEC as well. Did not check
it out up to the last bit but as far as I can see it is programmed to do
what the GAL guy said. What's more, a correctly programmed GAL should be
pin-compatible with the original 82S153. There's only one nasty possibillity
I can think about: there have been GALs on the market that did not meet the
full specs due to a mask fault. The company made new masks and sold the old
ones to another firm that used them to made there own GALs, including the
flaw. I never had a problem myself so it's only hearsay. Besides I'm not
sure the D-types were effected, but you may have run into this old problem.

I've tried three different types of GALs now (all different speeds
too) but the results are the same. So presumably that means I don't
have a faulty one - or do you mean that the guy who came up with the
original JEDEC was maybe using a faulty GAL?

You can make some hardware to compare the 82S153 and the GAL16V8D. An EPP
printerport, some LS364 latches and a LS245 buffer on a breadboard is all
you need. Feed the DUT with a counter, read back all outputs and save the
results on disk. Read the next device and compare the results.

I wouldn't know where to start there I'm afraid - not without a
schematic (and no, that's not a hint

Can't you find someone with a programmer that can read the old 82S153? It's
only combinatotial logic and FAIK they had no security bit. Somewhere I
still should have the software to make equationfiles from the JEDEC. It's
easier then building hardware.

Very true - I'll ask around.


Thanks for your help.

 

[Vin Collins]

John,

Thanks for your input, I was fairly certain I could do it this way. I looked
into VOX ckts and comparators etc,,,
Sometimes really simple ckts are best, and for a simplton such as myself
simple is about the only way to go.

BTW: This project is so I can prepare for a US Coast Guard flashing light
exam. Flashing light requirement for the exam is around 6 WPM.

Thanks again,

Vin Collins


"John Fields" <jfields@austininstruments.com> wrote in message
news:qrnpv1pi0n01rv3nrjljrc2g6dtur2renf@4ax.com...

On Wed, 22 Feb 2006 21:31:57 GMT, "Vin Collins" <nomail@spam.net
wrote:

I need to transform audio morse code into flashing light morse code.

My goal is to drive a light bulb to flash morse code from an audio speaker
level source output. (cassette player).

My grasp of the use of SCR's is very limited, but I was thinking of using
a
12.6v
filament transformer in series with an SCR and a light bulb, then use
the
audio output (external speaker) from a small cassette player to drive the
gate of the SCR. I am assuming the gate will detect the audio and drive
the
scr junction into conduction to light the bulb visually displaying the
dots
and dashes as flashing light.
What general use SCR available at Radio Shack might work in this
application.

---
Excellent description of what you want to do, and I can't see any
reason why it won't work, but I'd go for a TRIAC instead of an SCR
in order to get both halves of the 60Hz to drive the lamp.

Unfortunately, I can't help you with what RS has in stock, since a
search for "TRIAC" on their site goes basically nowhere.

The good news is you should be able to use pretty much any TRIAC you
can find as long as it can handle the lamp current and your cassette
player can supply the current to turn it on.

The bad news is...
Oh, wait... there isn't any bad news.

Your filament transformer will provide isolation from the mains, and
as long as your cassette player's got the guts and the TRIAC can be
fired in all four quadrants, you're home, free.



--
John Fields
Professional Circuit Designer

 

[Chris]

Vin Collins wrote:

John,

Thanks for your input, I was fairly certain I could do it this way. I looked
into VOX ckts and comparators etc,,,
Sometimes really simple ckts are best, and for a simplton such as myself
simple is about the only way to go.

BTW: This project is so I can prepare for a US Coast Guard flashing light
exam. Flashing light requirement for the exam is around 6 WPM.

Thanks again,

Vin Collins


"John Fields" <jfields@austininstruments.com> wrote in message
news:qrnpv1pi0n01rv3nrjljrc2g6dtur2renf@4ax.com...
On Wed, 22 Feb 2006 21:31:57 GMT, "Vin Collins" <nomail@spam.net
wrote:

I need to transform audio morse code into flashing light morse code.

My goal is to drive a light bulb to flash morse code from an audio speaker
level source output. (cassette player).

My grasp of the use of SCR's is very limited, but I was thinking of using
a
12.6v
filament transformer in series with an SCR and a light bulb, then use
the
audio output (external speaker) from a small cassette player to drive the
gate of the SCR. I am assuming the gate will detect the audio and drive
the
scr junction into conduction to light the bulb visually displaying the
dots
and dashes as flashing light.
What general use SCR available at Radio Shack might work in this
application.

---
Excellent description of what you want to do, and I can't see any
reason why it won't work, but I'd go for a TRIAC instead of an SCR
in order to get both halves of the 60Hz to drive the lamp.

Unfortunately, I can't help you with what RS has in stock, since a
search for "TRIAC" on their site goes basically nowhere.

The good news is you should be able to use pretty much any TRIAC you
can find as long as it can handle the lamp current and your cassette
player can supply the current to turn it on.

The bad news is...
Oh, wait... there isn't any bad news.

Your filament transformer will provide isolation from the mains, and
as long as your cassette player's got the guts and the TRIAC can be
fired in all four quadrants, you're home, free.



--
John Fields
Professional Circuit Designer

Hi, Vin. I happened to stop by the local Radio Shack, and found out
some bad news. Yet once again, Shack management is alienating
hobbyists, this time by reducing the variety of components in their
drawers (only available at some stores). SCRs are long gone, and the
last triac (276-1000, 400V/6A) has recently been obsoleted, and can't
be reordered.

Without having more information on your cassette recorder and speaker,
you have to make some assumptions. Personally, I would like to get a
somewhat higher voltage at the gate of the SCR or triac in the circuit
Mr. Fields is talking about (they won't always reliably trigger with
less than 2V at the gate), so I'd add a couple more components to give
you something like this (view in fixed font or M$ Notepad):

|
| 12.6VAC .-. 12.6VAC .-.
| o-----( X )------. o-----( X )------.
| '-' | '-' |
| Lamp | Lamp |
| | |
| | SCR | Triac
| 0.1uF V S4006 0.1uF _|_ Q4006
| || ___ - || ___ V_A
| o-||-o-|___|-o--/| o-||-o-|___|-o-//|
| Sig In|| | 10 | | Sig In|| | 10 | |
| - .-. | - .-. |
| 1N4001^ 100| | | 1N4001^ 100| | |
| | | | | | | | |
| | '-' | o o '-' |
| | | | | | |
| Com o----o------ o---' Com o----'------oo---'
|
(created by AACircuit v1.28.5 beta 02/06/05 www.tech-chat.de)

Tie the red speaker wire to Sig In, and one of the transformer
secondary leads to 12.6VAC. Tie the other end of the 12.6VAC
transformer secondary to COM, along with the black speaker wire, and
you should be OK. With the SCR or triac shown, you should have no
problem using a 12V bulb of up to 12 watts or so.

You can substitute just about any triac which has conduction in all
four quadrants for the one above. If you need something now, you just
might want to wander over to the local radio/TV repair shop, and see if
they've got a NTE/SK/ECG equivalent to the SCR or Triac you want. You
should still be able to get the other components at Radio Shack.

You're right -- KISS (Keep It Safe and Simple) is the way to go here.
Remember that, unless you're using an AC-to-AC wall wart, you should
fuse the mains input to the transformer just in case.

Good luck on the exam
Chris

 

[Chris]

Chris wrote:

snip
|
| 12.6VAC .-. 12.6VAC .-.
| o-----( X )------. o-----( X )------.
| '-' | '-' |
| Lamp | Lamp |
| | |
| | SCR | Triac
| 0.1uF V S4006 0.1uF _|_ Q4006
| || ___ - || ___ V_A
| o-||-o-|___|-o--/| o-||-o-|___|-o-//|
| Sig In|| | 10 | | Sig In|| | 10 | |
| - .-. | - .-. |
| 1N4001^ 100| | | 1N4001^ 100| | |
| | | | | | | | |
| | '-' | o o '-' |
| | | | | | |
| Com o----o------ o---' Com o----'------oo---'
|
(created by AACircuit v1.28.5 beta 02/06/05 www.tech-chat.de)
snip

Sorry -- try it again, this time with a 10uF electrolytic in place of
the 0.1uF cap:

|
| 12.6VAC .-. 12.6VAC .-.
| o-----( X )------. o-----( X )------.
| '-' | '-' |
| Lamp | Lamp |
| | |
| | SCR | Triac
| 10uF V S4006 10uF _|_ Q4006
| ||+ ___ - ||+ ___ V_A
| o-||-o-|___|-o--/| o-||-o-|___|-o-//|
| Sig In|| | 10 | | Sig In|| | 10 | |
| - .-. | - .-. |
| 1N4001^ 100| | | 1N4001^ 100| | |
| | | | | | | | |
| | '-' | o o '-' |
| | | | | | |
| Com o----o------ o---' Com o----'------oo---'
|
(created by AACircuit v1.28.5 beta 02/06/05 www.tech-chat.de)

Chris

 

[Joe Brophy]

Why not use a GFCI breaker in the breaker box?

On 13 Feb 2006 10:06:49 -0800, "w2aew" <w2aew@yahoo.com> wrote:

Rich,

That's not exactly true. The GFCI receptacles have a LINE input and
and LOAD output. Any receptacles connected to the LOAD output
terminals of the GFCI are also protected circuits.