Chip with simple program for Toy

[Rich Grise]

On Thu, 16 Feb 2006 13:01:47 -0800, logjam wrote:

I found his web page just a month or two ago also. But the relatively
short life of a relay worries me. I found a few auctions on ebay for
3000 relays at ~$200, but I don't want to hand wire such a thing.
SOMEONE needs to make a relay based web server. Maybe it only says
"Hello World", which would probably take about a minute or two...

When I thought about it last night I came up with a new solution. A
compromise between speed and board space. This is my first experience
with binary multiplication, so my first implimentation was very
wasteful!

I wanted to have a 64bit adder circuit with parallel carry generation,
but I forgot about fan-in/out. Getting to the end of the adder circuit
would require a LOT of components too. Maybe 16bit parallel by 4
serial is more reasonable.

Look up "Carry Lookahead".

Have Fun!
Rich

 

[Chris]

Rich Grise wrote:

[crossposted to sci.electronics.design,sci.electronics.basics,
followups to sci.electronics.basics]
On Fri, 17 Feb 2006 21:14:32 +1030, Robert Davies wrote:

Can anyone please tell me if this is good practice for building a
110VDC split rail power supply?

I intend to use 2 x 12VAC (unearthed) wall socket adaptors. Each
output is connected to the 12V side of 110V-12V transformer. The 110V
sides are connected in series, with the common becoming virtual earth.
One set of the usual rectifier and caps are then wired across this and
to each lead respectively to create the + and - rails.

I understand the back-to-back transformers provide isolation or
safety by limiting the current. However, I am unsure to what degree or
if the current ratings of the components are relevant as limiting
factors.


Yes, you can do this, and the limiting factors are isolation, which
a wall wart should have at least a couple hundred volts isolation,
and the power capability.

Add up the volt-amps of your outputs, and add, say, 20% to 50%; then
that should be the total volt-amps of the two wall-warts.

In other words, if you have a 12V, 1A wall wart, then you could get
120 (I'm using 120 because it's a more common way of referring to
line voltage, and it's _s00000_ much easier to do the arithmetic)
V at somewhat less than .1A - power out equals power in minus losses.

And, of course, you know that a rectifier/filter on a 110V secondary
will produce ~154V no-load, right?

Good Luck!
Rich

Hi, Rich. Herding cats again?

The OP is talking about backfeeding transformers, and backfeeding
AC-to-AC wall warts in particular. As near as I can make it out, he's
talking about something like this (view in fixed font or M$ Notepad):
|
| 120 VAC 12 VAC 12 VAC 120 VAC
| Pri. Sec. Sec. Pri.
| L1 T1 T2 +160V
| o----------. ,----------o--. ,-------. .---o---o
| )|( | )|( | | |
| )|( | )|( | .--------. | +|
| )|( | )|( | | | | ---
| )|( | )|( '--o~ +o -' ---
| L2 )|( | )|( | | |
| o-o--------' '-------o--)--' '----. | | | GND
| | | T3 | | BR1 | o---o
| | '--. ,----o | | |
| | )|( | | | +|
| | )|( === .--o~ -o--. ---
| | )|( GND | | | | ---
| | )|( | '--------' | |
| | )|( | | |
| '-----' '-------' '---o---o
| -160V
Fig. 1
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

where T2 and T3 are AC-to-AC wall warts. I'm assuming T1 is a regular
12VAC sec. transformer.

Generally, backfeeding transformers is a somewhat wasteful way to do
things, because you have to overrate them for a given load. They _do_
provide isolation, but they don't limit the current in and of
themselves. If you've got a 10VA load, you should get a minimum 15VA
transformer if you're backfeeding. It's usually cheaper to just get an
isolation transformer of the right VA rating. But it generally resides
on this side of the line (barely) of good practice.

Let's put it this way -- Backfeeding is OK, even though it's a little
ugly. I made and currently use a home brew high voltage power supply
that uses something like the setup you describe (with regular 12.6VAC
75VA transformers instead of wall warts), but I wouldn't sell something
like that to a customer, or make something like that for an employer.

A couple of things. First, if it's a light current load, it might be
more efficient to use just two transformers, like this:

|
| 120 VAC 12 VAC 12 VAC 120 VAC
| Pri. Sec. Sec. Pri.
| L1 T1 T2 +160V
| o----------. ,-------------. ,---------o--->|---o---o
| )|( )|( | |
| )|( )|( | +|
| )|( )|( | ---
| )|( )|( | ---
| L2 )|( )|( | |
| o----------' '-------------' '-----. | | GND
| ---)--------o---o
| | |
| | +|
| | ---
| | ---
| | |
| | |
| '----|<--o---o
| -160V
Fig. 2
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

The problem, of course, is that since the cap is only charged 60 times
a second instead of 120, you have to double up on the size of the cap.

Along with this is the OP's spec of a +/-110VDC supply. If he's
looking to drive a solenoid or relay, he can just lose the caps. If he
needs a filtered supply, though, and 160V is too high, he may want to
put a power resistor in series with the T2/T3 secondary before the
bridge rectifier, if he's got a steady load. That would have some of
the AC volts drop across the resistor before rectification, lowering
the output voltage.

The second thing to consider is that you still have to take normal
transformer ratings into account. If your +/- 160VDC supply in the
first figure requires +/-10VA DC load, you'll need a transformer rated
for 18VA (RMS current = 1.8 * DC current for bridge rectifier/capacitor
input filter. You then have to overrate by 50%, which will get you to
27VA. This is a minimum, and the OP should make sure that T1 is
somewhat bigger than twice the VA rating of T2 + T3. That would make
T1 at least a 60VA transformer.

I'm not happy with backfeeding AC-to-AC wall warts, though. They don't
typically have the isolation ratings of standard power transformers,
and their UL/CSA rating is definitely not based on backfeeding them,
which means you have to fuse. I would rather just use a standard
120/240 primary -- 120/240 secondary transformer, or if I had to
backfeed, I would rather just use standard transformers, and of course
use fuses as appropriate. The wall warts are too ugly here, and since
you'd need to fuse anyway, there's really no point.

The standard precautionary advice about high voltage definitely
applies. If you don't know what you're doing, don't do it. A setup
like this, even if it is isolated from the line, has the potential and
joules to kill. The OP should be sure to use appropriate precautions,
and make sure to have somebody within yelling distance while he's
working with the supply.

And standard precautionary advice about my math applies, too. Check it
first! ;-)

Good luck
Chris

 

logjam <grant@cmosxray.com> wrote:
: I want to design what would have been a super computer in 1975, using
: parts that would have been "easily" available. Several people have
: done this already, just not on an insane scale. My favorite is the
: Magic-1, which I'm currently designing PCBs for. It has been a GREAT
: learning experience studying the schematics from the Magic-1. I never
: thought much about what a computer did during the mysterious clock
: cycles between instruction cycles, and now with the microcode muxes,
: registers, it all just makes sense.

: Any way, I need my computer to be very good at math. The magic-1 is a
: 16bit Add/sub/compare machine. I want to make mine capable of 32bit
: operations and have a 32 bit data path.

: I'm starting with 32bit multiplication because it gets 32bit addition
: out of the way as well.

: I threw together a diagram of a 32*32 multiplier using around 1040 AND
: gates and 400 74283 Adder circuits. This schematic would be what I
: think is called "asynchronous".

: Once I completed my diagrams I remembered something horrible. There is
: a LOT of time spent waiting for the carry-in-out propagation in the
: hundreds of adders which leads me to building an adder out of XOR and
: AND gates. This comes at the added expense of power consumption board
: space, but should speed things up by about 250x. Could anyone suggest
: the best 1 bit addition "block" with carry? Its pretty late here and
: I'm starting to loose brain function.

: Crazy? Remember, a few weeks ago I completed soldering 19,008 LEDs to
: make a display...which I haven't finished yet... (building the drivers)

: One last thought for those of you who, well, you know who you are.
: Idle, what would the power consumption of some 600 odd ICs be? 20ma
: per device? This just might make more heat than a pentium!

: Now...for floating point...

While some others have suggested changes like using a
carry-lookahead adder for the final carry-propagate adder in the
multiplier, I would suggest that you also look into Booth encoding (the
two techniques can both be used.) At the expense of a little bit of extra
complexity to generate the partial products, you can cut the number of
rows of partial products approximately in half. As far as using a CLA for
the final adder, I think that that's a good idea, because, if you are
hell-bent on building this out of TTL parts,there is a 4-bit TTL
carry-lookahead block (74x182?, if I recall.)

So, a Booth-Array Carry-Save portion, followed by a
Carry-Lookahead Carry Propagate portion, will be fast, and do-able, if
you're really hell-bent on making this out of TTL parts. I also agree
with the other poster that said that you really should get yourself a FPGA
development platform, but whatever floats your boat!

Have Fun,

Joe

 

[Rich Grise]

On Fri, 17 Feb 2006 21:47:38 +0000, jwelser wrote:

logjam <grant@cmosxray.com> wrote:
: I want to design what would have been a super computer in 1975, using
: parts that would have been "easily" available. Several people have

: Crazy? Remember, a few weeks ago I completed soldering 19,008 LEDs to
: make a display...which I haven't finished yet... (building the drivers)

Yup. Crazy. Nuts. Certifiable. Bonkers. Wacko. Insane. ;-P
Stupid? Remains to be seen. ;-D ;-D ;-D

: One last thought for those of you who, well, you know who you are.
: Idle, what would the power consumption of some 600 odd ICs be? 20ma
: per device? This just might make more heat than a pentium!

: Now...for floating point...

Get the integers going first! ;-)

While some others have suggested changes like using a
carry-lookahead adder for the final carry-propagate adder in the
multiplier, I would suggest that you also look into Booth encoding (the
two techniques can both be used.) ...
[enlightening discussion of carry techniques snipped]

I've drawn a schematic using Xilinx's WebPack, of a 4x4 multiplier:
http://www.abiengr.com/~sysop/images/mult-4x4-sch.gif

The ANDs are just plain ANDs, and the ALU-looking thingies are nothing
but 1-bit full adders.

And I've been procrastinating on doing enough of their tutorials to
figure out how to do the guzintas[1] and the guzoutas[2] and schtuff. ;-)

Cheers!
Rich
[1] Goes Into
[2] Goes [comes] Out Of

 

[logjam]

So, a Booth-Array Carry-Save portion, followed by a
Carry-Lookahead Carry Propagate portion, will be fast, and do-able, if
you're really hell-bent on making this out of TTL parts. I also agree
with the other poster that said that you really should get yourself a FPGA
development platform, but whatever floats your boat!

Do you think I will gain anything useful while trying to use the fewest
parts to generate the result fast? From what I've seen so far of some
FPGA desings they're pretty wastful "because you can".

 

[logjam]

I think I've fallen in love with 74S274 and 74S275. I don't think the
130ns for a 32 bit product includes addition, maybe it does. I wonder
why these parts had to be killed off???

The parts are pretty expensive...$1.99 for a 274 and 2.99 for a 275,
but compared to a few hundred logic gates??? Using these chips I might
be able to get more than a million multiplications per second.

 

[logjam]

Here some links I found helpful:
http://www.ece.ucsb.edu/~kastner/ece154/slides/ece154-5.pdf
http://www.ecs.umass.edu/ece/koren/arith/slides/
http://www.iwu.edu/~wzhu/classes/cs256/

I think I like the combinational method used in the 1976 databook.
Very fast, exceeds everything else I've found.

I have two choices...use parts FROM 1975 for the circuit, or make it
out of modern 283s, etc. Using the origional 74S parts I estimate 2A
power consumption.

I've found list prices at:
74S274s for 1.99, I would need 64 of them
74S275s for 2.99, (I haven't quite figured this one out yet, somewhere
around 15)

I would need 4 74F283s for every 74S274, but they're pretty cheap. In
the end it would be smarter to go with 74S274s even though 256 16 pin
devices on a PCB would look cool. I could go either way on this one.
According to the 1975 ttl book a 74S283 completes a carry in 11ns
and a 74S274 4x4 in 45ns, so I assume the 74S274 is pretty much 4
74S283 and 16 AND gates The critical speed path is carry-in-out on all
the 64 partial products is typ 5ns for all the AND gates and then 34ns
through the adders (maximum of 7.5ns AND and 48ns adders).

As long as the circuit would work fine with the parts from the 75 I'm
happy. I don't need to buy a bunch of NOS chips, but I want to make
sure I account for the delay of the old chips.

I'll work a little more on this and post some schematics that hopefully
one of you can look over. This is pretty exciting for me.

 

[John Fields]

On 21 Feb 2006 08:08:57 -0800, "joshua"
<joshuathiagaraj@yahoo.co.in> wrote:

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

---
1. What do you mean by "perfect"?

2. What do you mean by "with display", or is it "with display
datasheet"?

3. http://folk.ntnu.no/shane/stasj/pics/humor/div/377.html


--
John Fields
Professional Circuit Designer

 

[Sambo]

matt wrote:

On Tue, 21 Feb 2006 16:11:14 +0100, "Deefoo" <nonono@wonttell.com
wrote:



-25 is for speed, not for age ;o)


I know that.


There is no reason to assume that your GAL would be of the right speed for a
25 year old PCB. Your GAL may be too fast or too slow. Don't you have the
original GAL?


No - the original chip was an 82S153 PLD, it's just that someone
converted the contents of that to JEDEC format to work with a modern
GAL (82S153's are hard to find and expensive). It worked for him, just
can't figure out why it won't work for me.

So perhaps I should buy and try a faster GAL? -15 perhaps? -10? -7?

Ah, pals and gals maybe I'll still get a chance to play with those.
I would say you are most likely already way too fast, 250-300ns RAMs in those days, 82S153 probably had propagation delay of at least 40ns come to think of it it is not even PLD it is a PROM hence even larger propagation delay can be expected. A quick glance on goole, I don't see anythink with specs ( so many useless hits these days $#*%^& ) It is not in the "CMOS cook Book" must be in "TTL Cook Book" anybody have it handy?
Of the top of my head I don't even think it has an enable signal which you could .....
The old slow part may be bridging the time the inputs stop being valid and the outputs are read (since I don't believe the part has output enable), the only way would be to buffer the outputs or use a device that could delay the outputs internaly.

Why it worked for the other person (with same circuit, same speed and type GAL ) can't say. Maybe you can get a bit slower GAL and get lucky.

Cheers

 

[petrus bitbyter]

"matt" <mattgyma@hotmail.com> schreef in bericht
news:43fb35cf.344841562@news.freeserve.net...

On Tue, 21 Feb 2006 16:11:14 +0100, "Deefoo" <nonono@wonttell.com
wrote:


-25 is for speed, not for age ;o)

I know that.

There is no reason to assume that your GAL would be of the right speed for
a
25 year old PCB. Your GAL may be too fast or too slow. Don't you have the
original GAL?

No - the original chip was an 82S153 PLD, it's just that someone
converted the contents of that to JEDEC format to work with a modern
GAL (82S153's are hard to find and expensive). It worked for him, just
can't figure out why it won't work for me.

So perhaps I should buy and try a faster GAL? -15 perhaps? -10? -7?

Maybe. But I'd be mistrust the conversion in the first place. Do you have
the JEDEC of the original 82S153? If memory serves, AMAZE can convert the
JEDEC back to logic equations so you can see what it is supposed to do. Once
you know that you can edit the source for a GAL and get the right JEDEC for
it.

petrus bitbyter

 

[Bob Myers]

"John Fields" <jfields@austininstruments.com> wrote in message
news:103nv11ia9h8ub06kaunh3ahvchhlcbsd9@4ax.com...

3. http://folk.ntnu.no/shane/stasj/pics/humor/div/377.html

Cruel, John, cruel...but definitely appropriate...

Bob M.

 

[matt]

On Tue, 21 Feb 2006 23:32:26 +0100, "petrus bitbyter"
<pieterkraltlaatditweg@enditookhccnet.nl> wrote:

So perhaps I should buy and try a faster GAL? -15 perhaps? -10? -7?

Maybe. But I'd be mistrust the conversion in the first place. Do you have
the JEDEC of the original 82S153?

Afraid not, no.

If memory serves, AMAZE can convert the
JEDEC back to logic equations so you can see what it is supposed to do.

The problem then, for me at least, is understanding them.

Once
you know that you can edit the source for a GAL and get the right JEDEC for
it.

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

 

[matt]

On Tue, 21 Feb 2006 17:28:32 -0500, Sambo <sambo@void.com> wrote:

Ah, pals and gals maybe I'll still get a chance to play with those.
I would say you are most likely already way too fast, 250-300ns RAMs in those days, 82S153 probably had propagation delay of at least 40ns
come to think of it it is not even PLD it is a PROM hence even larger propagation delay can be expected. A quick glance on goole, I don't
see anythink with specs ( so many useless hits these days $#*%^& ) It is not in the "CMOS cook Book" must be in "TTL Cook Book" anybody have it handy?
Of the top of my head I don't even think it has an enable signal which you could .....
The old slow part may be bridging the time the inputs stop being valid and the outputs are read (since I don't believe the part has output enable),
the only way would be to buffer the outputs or use a device that could delay the outputs internaly.

Hmmm, thanks. Wish I could find a slower GAL! Do they still exist?

Why it worked for the other person (with same circuit, same speed and type GAL ) can't say. Maybe you can get a bit slower GAL and get lucky.

That's the problem - any ideas where from?

 

[John Popelish]

John Fields wrote:

On Tue, 21 Feb 2006 11:43:10 -0500, John Popelish
jpopelish@rica.net> wrote:
....
This combination generates an endless echo with a
duration equal to the period of the quartz resonance.
...

"Endless echo". That's nice.

Thanks. I think it is descriptive, too. Unlike RC oscillators, that

generate each half cycle from scratch, just stacked after the previous
half cycle, some energy from previous cycles goes back around to make
up the next cycle in resonator oscillators. I think it is a
distinction worth making.

 

[John Popelish]

ErikBaluba wrote:

Hi,

What is the benefit/usage of a "self-induction recuperation diode" ?

I saw a motor driver schematic with an L298N motor driver, and two diodes
were used at each of the four outputs, connected to VDD and GND
respectively. Is this to clamp negative and positive spikes generated by the
motors to GND and VDD respectively? If so, what does the self-induction mean
in this context?

erik


Any magnetic (inductive) device stores energy in proportion to the

square of current passing through it. If you break connection to both
ends of the inductive load, you can recover most of the stored energy
back into the supply with two diodes. If you charge up and dump the
inductive load often, this can amount to a considerable energy
savings. The alternative is to just turn that energy into heat to get
rid of it.

 

[Bob Masta]

On 21 Feb 2006 22:48:20 -0800, "joshua" <joshuathiagaraj@yahoo.co.in>
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

A 16-bit converter has 2^16 possible states;
a 24-bit converter has 2^24. But note that
in the real world this difference is *very* hard to
realize, due to the noise floor of typical analog
circuits. That's because there are definite
limits on how high the input voltage can be,
so you have to try to resolve ever-lower voltages
to increase resolution. With a 16-bit ADC having
a 0-4.096 V input range, the resolution is 62.5 microvolts.
With a 24-bit ADC covering the same range, the
resolution is 0.244 microvolts. Not many circuits
with noise that low!

Best regards,




Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

 

[Chris]

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

 

[petrus bitbyter]

"matt" <mattgyma@hotmail.com> schreef in bericht
news:43fba7bb.374210390@news.freeserve.net...

On Tue, 21 Feb 2006 23:32:26 +0100, "petrus bitbyter"
pieterkraltlaatditweg@enditookhccnet.nl> wrote:

So perhaps I should buy and try a faster GAL? -15 perhaps? -10? -7?

Maybe. But I'd be mistrust the conversion in the first place. Do you have
the JEDEC of the original 82S153?

Afraid not, no.

If memory serves, AMAZE can convert the
JEDEC back to logic equations so you can see what it is supposed to do.

The problem then, for me at least, is understanding them.

Once
you know that you can edit the source for a GAL and get the right JEDEC
for
it.

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.

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 82S143 content
and same object GAL? (So same type and brand?) Any idea what the GAL is
supposed to do? Any problem posting the JEDEC(s) you have? (Part of) the
schematic?

petrus bitbyter

 

[PeteS]

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

 

[ErikBaluba]

....

Any magnetic (inductive) device stores energy in proportion to the
square of current passing through it. If you break connection to both
ends of the inductive load, you can recover most of the stored energy
back into the supply with two diodes. If you charge up and dump the
inductive load often, this can amount to a considerable energy
savings. The alternative is to just turn that energy into heat to get
rid of it.

Thanks for sharing your valuable knowledge John,

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.

But what would really happen if the diodes weren't there? 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? Also, are the diodes there to also
protect the outputs of the 298 driver IC from spikes caused by
self-induction in the motor?

erik