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To fuse equipment or not to?
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Fred Bloggs
electronics forum Guru


Joined: 25 Mar 2005
Posts: 2468

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: Triac or relay to switch AC power? Reply with quote

Jean wrote:
Quote:
Triac or relay to switch AC power?

I want to use a controller to switch for an hour the AC power of a
light bulb.
Should I use a triac or a relay?
Besides the circuit needed to drive the triac or the relay, what are
the parameters I should be aware of to choose between the triac and
relay?
In both cases, the controller has to keep sending the signal for an
hour; The circuit around the controller will use current for an hour
and I am concerned about this consumption and want to keep this
consumption as low as possible.

The simplest way to achieve success without knowing much about
electronics is to use an AC relay actuated by a your controller through
a TRIAC. The sizing of the relay driving an incandescent load has to be
adjusted downward from the maximum current rating of the relay to
something like 30-40% because of the cold filament surge and possible
filament failure scenarios. So if your bulb is say 300W @ 240VAC, then
I=W/V=300/240=1.25A -use a relay with contacts rated at 5A @240VAC and
240VAC coil. Then use a 600V TRIAC with 1A or more current rating to
drive the coil like so:

View in a fixed-width font such as Courier.

.
.
. +--------------+
. | / |
. LINE -----------|--+-----o o---|----------------->
. | | | TO LAMP
. | K|| |
. | K|| | +---->
. | K|| | |
. | K|| | |
. | K|| | |
. | | | |
. Rs=100 ohm +--------------+ |
. flameproof | |
. | |
. Cs=0.1u 1000V | |
. | |
. +-----+ |
. | | +-------+ |
. [Rs] | TRIAC |* | |
. | --- | OPTO | |
. | ^ v/ -------| DRIVE | |
. === --- | | |
. Cs | +-------+ |
. | | | |
. NEUTRAL-----+-----+--------------+---------+
.
.
.
. * see http://www.fairchildsemi.com
.
. sold through Mouser
.
.
.
.
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Rhyanon
electronics forum beginner


Joined: 24 Mar 2005
Posts: 1

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: OT: Safe Riddles Reply with quote

Hehehehe. If you really want to know, or if you can manage to figure it out,
I use such tactics to press the buttons of juvenile [or puerile] males such
as yerself. Would you rather I pushed your homophobe button? Or are you more
a racist sort? No worries; I can yank yer chain no matter what your pathetic
issues are.

"keith" <krw@att.bizzzz> wrote in message
news:pan.2005.02.02.03.31.19.831939@att.bizzzz...
Quote:
On Tue, 01 Feb 2005 07:11:05 -0600, Rhyanon wrote:

Sorry, but I think you should keep your mom in the act. I doubt I have
what
it takes [eeeech] to replace her. For one thing, how would I get a wart
that
size? Oh, that's her head -- hey, you two look just alike......

Yawn. You seem to have an Oedipus complex. That may be natural for
juvenile males, but as a female (perhaps a bad assumption) you shouldn't
be having these issues. Seek help!

--
Keith
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Wouter van Ooijen (www.vo
electronics forum addict


Joined: 02 May 2005
Posts: 63

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: Electronics Magazines Reply with quote

Quote:
One of the best mags is Elector/Elektuur. I think it comes from Holland.

Make that 'was' instead of 'is'. They have a bad reputation for using
unobtaineable of obsolete components.


Wouter van Ooijen

-- ------------------------------------
http://www.voti.nl
Webshop for PICs and other electronics
http://www.voti.nl/hvu
Teacher electronics and informatics
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Leon Heller
electronics forum addict


Joined: 30 Apr 2005
Posts: 71

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: hobby pcb fabrication kits Reply with quote

"Rene Tschaggelar" <none@none.net> wrote in message
news:4200b4b5$1@news1.ethz.ch...
Quote:
DG wrote:

Any suggestions for starting up a little hobby setup for making PCBs? I
was thinking of getting the MG Chemicals 416-K kit. Comes with 3
sensitized copper-clad (single-sided boards), developer, ferric chloride,
foam brushes, rubber gloves. Any reason to not use ferric chloride, and
maybe sodium persulfate instead? I'm something economical to make little
boards for PICs and some peripheral circuitry, preferable, it would be
possible to make pads for little ICs SSOP, TSOP, etc...

If you don't know answers but know websites, those are appreciated as
well.

You shouldn't target smaller structures than 15mil
trace width and 15mil trace distance. The narrower holes
shouldn't be below 28mils.

I don't have any problems with 12/12 mil tracks, and can go down to 10 mils,
with my home-made PCBs.

Leon
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Wouter van Ooijen (www.vo
electronics forum addict


Joined: 02 May 2005
Posts: 63

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: Electronics Magazines Reply with quote

Quote:
Circuit Cellar - www.circuitcellar.com

Well the field isn't that big. I think the only other one
left is Nuts & Volts.

+ EPE magazine

+ Elektuur/Elektor

Imho CC is by far the best, EPE and Elektuur are in the middle group,
N&V is realy low level.


Wouter van Ooijen

-- ------------------------------------
http://www.voti.nl
Webshop for PICs and other electronics
http://www.voti.nl/hvu
Teacher electronics and informatics
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Fred Bloggs
electronics forum Guru


Joined: 25 Mar 2005
Posts: 2468

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: Triac or relay to switch AC power? Reply with quote

Fred Bloggs wrote:
Quote:


Jean wrote:

Triac or relay to switch AC power?

I want to use a controller to switch for an hour the AC power of a
light bulb.
Should I use a triac or a relay?
Besides the circuit needed to drive the triac or the relay, what are
the parameters I should be aware of to choose between the triac and
relay?
In both cases, the controller has to keep sending the signal for an
hour; The circuit around the controller will use current for an hour
and I am concerned about this consumption and want to keep this
consumption as low as possible.


The simplest way to achieve success without knowing much about
electronics is to use an AC relay actuated by a your controller through
a TRIAC. The sizing of the relay driving an incandescent load has to be
adjusted downward from the maximum current rating of the relay to
something like 30-40% because of the cold filament surge and possible
filament failure scenarios. So if your bulb is say 300W @ 240VAC, then
I=W/V=300/240=1.25A -use a relay with contacts rated at 5A @240VAC and
240VAC coil. Then use a 600V TRIAC with 1A or more current rating to
drive the coil like so:

View in a fixed-width font such as Courier.

.
.
. +--------------+
. | / |
. LINE -----------|--+-----o o---|-----------------
. | | | TO LAMP
. | K|| |
. | K|| | +----
. | K|| | |
. | K|| | |
. | K|| | |
. | | | |
. Rs=100 ohm +--------------+ |
. flameproof | |
. | |
. Cs=0.1u 1000V | |
. | |
. +-----+ |
. | | +-------+ |
. [Rs] | TRIAC |* | |
. | --- | OPTO | |
. | ^ v/ -------| DRIVE | |
. === --- | | |
. Cs | +-------+ |
. | | | |
. NEUTRAL-----+-----+--------------+---------+
.
.
.
. * see http://www.fairchildsemi.com
.
. sold through Mouser
.
.
.
.


Maybe the simplest in your case would be to use a DPDT AC relay
configured as self-latching, and then use timer to pulse two logic level
mini-relays ( one with normally close,nc, the other with normally open
,no, contacts) with AC rated contacts to initiate ON/OFF operation. The
quiescent overhead from the controller is now zero.
View in a fixed-width font such as Courier.

..
. DPDT AC PWR RELAY
. +--------------+
. | / |
. LINE -----------|--+-----o o---|----------------->
. | | | TO LAMP
. | K|| |
. | K|| | +---->
. | K|| | |
. | K|| | |
. | K|| | |
. | | | |
. | +--------+ | |
. | | | | |
. | o | | |
. | / | | |
. | o | | |
. | | | | |
. +--------------+ |
. | | |
. | | |
. o o |
. nc | <-. no / <--. |
. o | o | |
. | | | | |
. NEUTRAL-----------+----|---+-----|---------+
. | |
. OFF ON
. | |
. from two separate
. mini-relays on
. controller board
. 250ms pulse operation
.
.
.
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Rene Tschaggelar
electronics forum Guru


Joined: 24 Mar 2005
Posts: 540

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: hobby pcb fabrication kits Reply with quote

Leon Heller wrote:

Quote:
"Rene Tschaggelar" <none@none.net> wrote in message
news:4200b4b5$1@news1.ethz.ch...

DG wrote:


Any suggestions for starting up a little hobby setup for making PCBs? I
was thinking of getting the MG Chemicals 416-K kit. Comes with 3
sensitized copper-clad (single-sided boards), developer, ferric chloride,
foam brushes, rubber gloves. Any reason to not use ferric chloride, and
maybe sodium persulfate instead? I'm something economical to make little
boards for PICs and some peripheral circuitry, preferable, it would be
possible to make pads for little ICs SSOP, TSOP, etc...

If you don't know answers but know websites, those are appreciated as
well.

You shouldn't target smaller structures than 15mil
trace width and 15mil trace distance. The narrower holes
shouldn't be below 28mils.


I don't have any problems with 12/12 mil tracks, and can go down to 10 mils,
with my home-made PCBs.

On a whole Eurocard ? I faced the problem that etching is
somewhat uneven and while at one side the copper is still
unbroken, at the oder side it already starts to etch under
the varnish. Side means here back/front as well as left/right.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net
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Anders F
electronics forum beginner


Joined: 24 Mar 2005
Posts: 19

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: is it possible to interface SPI to serial? Reply with quote

"Tim Wescott" <tim@wescottnospamdesign.com> wrote in message
news:10vvs4494dlguec@corp.supernews.com...
Quote:
Michael Noone wrote:

Hi - I'm looking to connect an RF chip with an SPI interface
(http://www.nordicsemi.no/index.cfm?obj=product&act=display&pro=83) to a
computer through the serial port. Right now I'm just planning on putting
a
microcontroller that has both a uart and an spi interface between the
computer and the chip - but are there any more elegant solutions?
Thanks,

Michael

Nope, that's probably the best. Look around, there should be some very
small solutions. Don't overlook parts that have UARTs but no SPI -- SPI
is easy to bit-bang. If you hold the baud rate down and you don't mind
consuming lots of processor resources you can even bit-bang asynchronous
serial; I believe that Microchip has app notes.

I think they all have. And I know Texas has for the MSP430.

/Anders

Quote:
--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
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Fred Bloggs
electronics forum Guru


Joined: 25 Mar 2005
Posts: 2468

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: OT: reaction to Iraqi elections Reply with quote

John Larkin wrote:

Quote:


Right. Installing a freely elected representative government is indeed
a fiendishly clever way to get the US to pull out. Those rascals!


Here is the victory statement of the undisputed winner, the election was
by UN resolution- looks like the US loses- the quislings are out:

Abdul Aziz al-Hakim claimed victory in the Sunday elections for the
United Iraqi Alliance, the coalition of religious Shiite parties he
leads. And this is what the winners, if they are winners, think of the US:

' "No one welcomes the foreign troops in Iraq. We believe in the ability
of Iraqis to run their own issues, including the security issue," Mr
Hakim said. "Of course this issue could be brought up by the new
government." '
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Roger Hamlett
electronics forum Guru


Joined: 28 Apr 2005
Posts: 302

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: is it possible to interface SPI to serial? Reply with quote

"Wim Ton" <wimton@blueyonder.co.uk> wrote in message
news:3t0Md.44952$v8.34970@fe2.news.blueyonder.co.uk...
Quote:

"Michael Noone" <mnoone.uiuc.edu@127.0.0.1> wrote in message
news:Xns95F09555824A3mnooneuiucedu127001@216.148.227.77...
Hi - I'm looking to connect an RF chip with an SPI interface
(http://www.nordicsemi.no/index.cfm?obj=product&act=display&pro=83) to
a
computer through the serial port. Right now I'm just planning on
putting a
microcontroller that has both a uart and an spi interface between the
computer and the chip - but are there any more elegant solutions?
Thanks,

Michael
Look at the Maxim 3100 family. These are SPI interface UARTs, complete

with the line drivers built in.

Best Wishes
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Fred Bloggs
electronics forum Guru


Joined: 25 Mar 2005
Posts: 2468

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: CHEAP Serial bus, control 200 devices, 50 meters Reply with quote

Armin Steinhoff wrote:
Quote:
Brook Stevens wrote:

Rene Tschaggelar wrote:


I'd go for RS422, a bidirectional bus with one leading in
each direction. Physically identical to the RS485, it doesn't
require you to switch direction at the cost of an additional
line pair. There are input impedances that limit the number
of devices to 32 or 128, depending on the receivers.
So after the number of devices is reached, just add a
repeater.
I'd use 6 wires for the bus. 4 wires for the signal plus
one for GND and +5V. This would enable you to have the local
RS422_to_CMOS plus perhaps isolators powered from the bus.



Thanks Rene. RS-422 seems like a good option for the bus.


RS-422 is not the right choice for a BUS. RS-422 can be used for a
one-to-one (or one to many) communication structure.

Use RS-484 ... or simply CAN and you go with a standard.

Armin


But, then what
protocol should the devices use to communicate with the PC? The PC
needs to
address one out of 200 devices and tell it to set it's outputs, or to
send
it's inputs.



What's the matter with industrial ethernet, using that cheap 8051 Rabbit
thing with TCP/IP stack- proprietary boards should come in at <$10 in
quantity- just tell the nodes to shut up unless spoken to- no
crashes/clashes or whatever they're called- cheap UTP cabling.
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Tam/WB2TT
electronics forum Guru Wannabe


Joined: 17 May 2005
Posts: 106

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: 40 amp power supply ??? Reply with quote

"rijo1" <rijo1@nonemonet.com> wrote in message
news:42005573.92C0EC8E@nonemonet.com...
Quote:
Hi , I need to build a 40 amp power supply that has an input voltage
of 120 volts and an output voltage of 12 volts - 13.5 volts . The power
supply will be used for amateur radio so it needs to be quiet . The
transformer I want to use will come out of a battery charger . I need to
regualte the voltage to DC at the voltages I have specified .
I don't want to use a battery charger and a battery for a power
source .
If anyone has a good design and is willing to send me schematics on
it , please send it to me . Be sure to remove no in front of (
nemonet.com.)
Thanks , Rick

Rick,


Save yourself a lot of trouble and buy a power supply meant for ham radio
use. Astron makes a linear supply that is in your current range. It is
quiet, because there is no fan. Ripple is very low. I have their 70 amp
supply, and it is built like a tank.

I had thought to build my own, but the transformer from Newark cost almost
as much as the whole Astron. See HRO, AES, or TexasTowers for prices. Note
that at 40 A, you can easily spend $50 just for the heat sinks.

Tam/WB2TT
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Mark Jones
electronics forum addict


Joined: 03 Feb 2005
Posts: 61

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: A-D front end - robust and for high voltage Reply with quote

Tom Del Rosso wrote:
Quote:
"keith" <krw@att.bizzzz> wrote in message
news:pan.2005.02.02.02.54.40.96579@att.bizzzz...

Sure, but "big resistor" isn't so sensitive to "small switch resistance"
and "low bandwith" doesn't have to have the high capacitance of the
FET switches compensated for. It's all about bandwidth.


I'm sorry I haven't been very explicit about what has me baffled. What I
don't understand is how those small switches can take the high voltage
sometimes present. For low ranges I think there has to be a switch near the
top of the divider, right? If so, why doesn't it get fried when there's a
high-voltage input?



200Vce bipolars/fets?

-- Kzizz to Ikzik: "Hey Ik... didn't we pass that barn an hour ago? YOU IDIOT,
WE'RE FLYING IN CROP CIRCLES!!!"
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Jerry Avins
electronics forum Guru Wannabe


Joined: 29 Apr 2005
Posts: 127

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: CHEAP Serial bus, control 200 devices, 50 meters Reply with quote

Rene Tschaggelar wrote:

...

Quote:
Ooohhhh, nooooooo.
Never attempt to control a process with a PC. A PC is not
reliable enough. Nor can a timing be guaranteed.
A floting point error in some unimportant display routine
can stop the application.
You always have to consider the PC stops working. The
motors running keep running. The heaters keep
heating. Leave the process control to embedded devices and
feed them from the PC. Such a system has to be and stay in
a safe state when the PC fails. Whenever that may happen.
This means the PC tells a controller to do something and
then leaves this device. You may also have to design failsafe
states, meaning when the controller was not updated for
however long, it goes to a certain state. EG heater off.

Best advice so far!

Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
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Ken Smith
electronics forum Guru


Joined: 06 May 2005
Posts: 1727

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: ASIC costs Reply with quote

In article <1107327244.420994.164280@f14g2000cwb.googlegroups.com>,
Frank Raffaeli <SNIPrf_man_frTHIS@yahoo.com> wrote:
Quote:
Presuming a lot of things:

Solution 1: No ASIC: Put the embedded micro, 500 macrocells into an
FPGA. Get rid of (almost) all the analog ... put that in the FPGA too
... digital filtering. Memory ... if you can use SDRAM, leave it
outside ... $1.25 to $2.00. Total cost < 10.00 + ADC.

This is more or less the direction I've intended but I want to compare it
with others. Converting the analog to digital is a bit of a problem. The
extra prop. delay could be serious trouble for part of the system.

Quote:

What does it do?

I could tell you but then I'd have to kill you. It is a secret that I
really-really don't want to give away.

Quote:
More information please. The mask set for a large
mixed signal ASIC (0.35 micron) can cost about $275K. The engineering
NRE ... depends. How many?

Not as many as you may think the ASIC is going to be expensive on a per
unit basis, but other solutions are expensive too.

--
--
kensmith@rahul.net forging knowledge
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