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PeterSmith1954@googlemail
electronics forum addict
Joined: 04 Jul 2006
Posts: 79
|
 Posted: Wed Aug 09, 2006 10:00 pm Post subject:
Re: What is important to look in OPTOEMITTERS?
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quanghoc@gmail.com wrote:
| Quote: | This is an entrepreneur project, no grading...
I just try to get a clear idea of the industry although I have no idea
in electronics.
I agree that it is really up to the application. But if anyone goes on
a web site, what do they rather want to see on the search result?
Thanks.
Jonathan Kirwan wrote:
On 9 Aug 2006 13:52:38 -0700, quanghoc@gmail.com wrote:
Hi, I am doing a school project (not electronic project) and I want to
know how people buy OPTOEMITTERS. Can you tell me the 5 most important
attributes when you buy it? Or if you can, please help me to rank these
attributes below in order.
Model
Soldering Temperature (Iron)
Soldering Temperature (Flow)
Collector Emitter Voltage
Emitter Collector Voltage
Power Dissipation
Peak Sensitivity
Reception Angle
Collector Emitter Dark Current
On-State Collector Current Min
On-State Collector Current Max
Saturation Voltage
Rise Time
Fall Time
Light Current Slope
Knee Point
Package/Case
Mounting Type
Thanks.
Normally, I'd imagine, that the application determines the ordering
and other entries showing up not mentioned above.
Is this supposed to be a business/marketing project you get graded on?
Jon
|
As noted, it depends on the application, but the soldering
temperatures are highly unlikely to be important for an initial search
- note that RoHS compliance may _well_ be, though. Soldering
temperatures are **expected** to be compatible with existing
technologies (non-RoHS and RoHS are different) and should not need to
be displayed on the primary results page.
Most engineers would be looking _first_ at the opto specs, although the
package type could easily be _part_ of the search as we may have
decided we need a surface mount (or through hole) part in the
application.
Cheers
PeteS |
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The Chimp
electronics forum addict
Joined: 15 May 2006
Posts: 60
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| Posted: Wed Aug 09, 2006 10:56 pm Post subject:
Re: Ceramic capacitor polarity trick
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On Tue, 08 Aug 2006 20:47:21 +0000, Lostgallifreyan wrote:
| Quote: | John Woodgate <jmw@jmwa.demon.co.uk> wrote in
news:yRxaY03lYP2EFwsS@jmwa.demon.co.uk:
In message <pan.2006.08.09.20.08.41.745396@example.net>, dated Tue, 8
Aug 2006, Rich Grise <rich@example.net> writes
I live a few miles from Norwalk, CA and all I can think of when I see
the signs is "Neither run, Norwalk." ;-)
Have you seen this thing going round the net about a racehorse called
'Norfolk and Chance'?
Wear the fox hat?
|
The Fugawi Indians got it. 
--
Cheers!
Rich^H^H^H^HBoBo |
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Rich Grise
electronics forum Guru
Joined: 24 Mar 2005
Posts: 3971
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| Posted: Wed Aug 09, 2006 11:30 pm Post subject:
Re: What is important to look in OPTOEMITTERS?
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On Wed, 09 Aug 2006 13:52:38 -0700, quanghoc wrote:
| Quote: | Hi, I am doing a school project (not electronic project) and I want to
know how people buy OPTOEMITTERS. Can you tell me the 5 most important
attributes when you buy it? Or if you can, please help me to rank these
attributes below in order.
|
"optoemitter" is an extremely broad cagegory, covering everything from
a campfire to an incandescent bulb to a LED to an excimer laser to a
thermonuclear detonation.
Can you be any more specific?
Thanks,
Rich |
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Jiks
electronics forum beginner
Joined: 09 Aug 2006
Posts: 3
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| Posted: Thu Aug 10, 2006 2:10 am Post subject:
Re: Electrolitic Capacitors
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Rich Grise wrote:
| Quote: | On Tue, 08 Aug 2006 18:21:22 -0700, JikkuJose wrote:
What will happen if u connect an electrolitic capacitor, in opposite
polarity ??
It will destroy the capacitor - it might not explode, but the capacitor
will be rendered useless.
Sorry )-;
Rich
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Will by any means be a short.... i think i read in Sedra i suppose ... |
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Tim Williams
electronics forum Guru
Joined: 18 May 2005
Posts: 668
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| Posted: Thu Aug 10, 2006 2:11 am Post subject:
Electrical pt.2
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Ok, so I looked at the 50A circuit installed in the basement.
The socket is a NEMA 50-R: three prongs; polarized and a round prog. A 50A,
240V model of the three-prong 120V, 15A socket. Inside its box, red, black
and white wires connect to their respective terminals. A bare wire grounds
the box somewhere (I forget if it's at the box, or at the EMT). EMT runs up
the wall and turns into a four-wire cable, which runs along the ceiling back
to the panel. At the panel, white (neutral) and bare are grounded to the
common buss, while red and black go to the breaker.
My questions: is the white wire suitable for circuit current, i.e.,
utilizing the circuit as 120-0-120 rather than just 240V? It is the same
guage as the hot wires. Is it a good idea to ground a chassis to neutral?
Seems odd to me to ground to a current-carrying wire, but there are only
three prongs. Should the project be bonded to ground with a seperate wire?
Tim
--
Deep Fryer: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms |
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cobsdb@hotmail.com
electronics forum beginner
Joined: 10 Aug 2006
Posts: 1
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| Posted: Thu Aug 10, 2006 2:15 am Post subject:
Zenith Model H511 tube radio, please help with identifying value of ceramic capacitor
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I am repairing a Zenith Model H511 tube radio 1951 model.
It has a brown disk ceramic capacitor that has the numbers
22 (dot) 5 in blue letters. < that is a (dot) not a (period)
There are not other markings.
I have looked at a few capacitor numbering data sheets
on the web but I am still not sure about the value.
Is it a 2.2 microfarad ?
Any help would be greatly appreciated
Thank You |
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John Popelish
electronics forum Guru
Joined: 29 Apr 2005
Posts: 1601
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| Posted: Thu Aug 10, 2006 2:56 am Post subject:
Re: Why Collector ??
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Jiks wrote:
| Quote: | i think, i will express my problem exactly :
WHY DOES THE ELECTRONS EMITTED TO THE BASE "JUST" SIMPLY LEAVE THE BASE
THROUGH THE BASE LEAD RATHER THAN GOING INTO THE HUGE RESISTIVE
COLLECTOR REVERSE BIAS DIRECTION ??????????
|
The reason this happens is the reason you can't very well roll marbles
down the length of a slightly tilted yard stick. The base path is
very long and thin. Once an electron falls off on the collector side,
it encounters an electric field that sweeps it away to the collector
terminal. It can't fall off the emitter side, because it feel down
(potential energetically speaking) from the emitter to appear in the
base, to begin with. That direction is uphill.
Transistors have power gain, because a small voltage (a diode forward
bias drop times a small base current) controls a much larger power (a
much larger collector current times a much larger collector voltage).
How this happens, is what I described earlier. It is all about
drift (movement caused by voltage) and diffusion) random motion caused
by heat). A junction transistor is a heat operated device. They
don't work near absolute zero temperature. |
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Henry
electronics forum beginner
Joined: 26 Jun 2005
Posts: 24
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| Posted: Thu Aug 10, 2006 3:31 am Post subject:
Re: Question about DRAM IC's
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Hey Alison.
Thanks for the link. Funny how the SIMM worked with their system, but 4bit
IC's don't seem to work with mine. I still have a couple tests I need to do
though as I have had some new ideas since the last post.
I also have purchased the DigiView logic analyzer. It should help me
determine what is actually going on. Now I just need to sit down and
continue my testing.
Thanks again for the link!
Henry
"techie_alison" <techie_alison@yahoo.co.uk> wrote in message
news:HZKdnRclDI5EdE7ZRVnyrg@bt.com...
| Quote: |
"Henry" <apl2research(.a.t.)comcast.net> wrote in message
news:-62dnUtYgZofIznZnZ2dnUVZ_oGdnZ2d@comcast.com...
Henry,
Further to my post in the depths of the thread below, check this out too..
http://atari.nvg.org/stacyram/
Good luck! :-)
Alison
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Blake
electronics forum beginner
Joined: 14 May 2005
Posts: 17
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| Posted: Thu Aug 10, 2006 4:27 am Post subject:
Re: Voltage Regulator help
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"Matthew Bonacci" <grimmier@gmail.com> wrote in message
news:1155155691.462537.179580@p79g2000cwp.googlegroups.com...
.. . . Basically the regulator is going
| Quote: | to be used on the 2 wires feeding the magneto to generate my magnetic
field for charging purposes.
|
Two wires feeding the "magneto" to generate a magnetic field? Sounds like
you're describing an alternator. An alternator uses a field winding to
generate a current-controlled magnetic field. A magneto uses permanent
magnets for the magnetic field.
I'm not at all familiar with the electrical system on your bike, but to
regulate the alternator output voltage by adjusting the field current is a
very different task than what a linear voltage regulator lime the LM117
does. I would think you would need to compare the alternator output voltage
to a reference, integrate the difference, and drive the field coil with a
transconductance amplifier.
But if I remember my car's electrical system correctly, they actually use
the battery to do most of the voltage regulation. The "voltage regulator"
toggles between two field current levels, fast charge and trickle charge.
This simply involves two resistors, a relay to switch between them, and a
comparator to sense when to make the switchover from low to high. I don't
know if your bike is made to work the same way.
If you wanted to build a regulator as a fun learning project, I would
encourage you to go for it. But to save money? Unless your time's worth just
about zero, you'll come out ahead paying the $100.
Any chance of opening up your failed unit and repairing it? If so, that
would be a lot better than reinventing the wheel. After all, the original
design was developed with the help of a number of lessons learned the hard
way. |
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Don Lancaster
electronics forum Guru
Joined: 30 Apr 2005
Posts: 416
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| Posted: Thu Aug 10, 2006 4:57 am Post subject:
Re: Ceramic capacitor polarity trick
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Bobo The Chimp wrote:
| Quote: | On Tue, 08 Aug 2006 20:47:21 +0000, Lostgallifreyan wrote:
John Woodgate <jmw@jmwa.demon.co.uk> wrote in
news:yRxaY03lYP2EFwsS@jmwa.demon.co.uk:
In message <pan.2006.08.09.20.08.41.745396@example.net>, dated Tue, 8
Aug 2006, Rich Grise <rich@example.net> writes
I live a few miles from Norwalk, CA and all I can think of when I see
the signs is "Neither run, Norwalk." ;-)
Have you seen this thing going round the net about a racehorse called
'Norfolk and Chance'?
Wear the fox hat?
The Fugawi Indians got it.
|
http://www.norfolkandwaay.com
--
Many thanks,
Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: don@tinaja.com
Please visit my GURU's LAIR web site at http://www.tinaja.com |
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sly.psi@gmail.com
electronics forum beginner
Joined: 10 Aug 2006
Posts: 1
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| Posted: Thu Aug 10, 2006 7:53 am Post subject:
Suggestions for aspiring hobbyist
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There must be a million of these posts on this group and I apologize in
advance if I'm violating some rule.
I come from a computer science background and I'm now looking to get
into electronics as a hobby. I have a few ideas for circuits I'd like
to construct eventually, most of which revolve around various sensors
and audio processing. One specific circuit I'd like to build a sample
& bit rate reducer for an electric guitar or bass signal with a
CV-controlled LFO to control the intensity of the effect.
Anyway, I've been reading books by Forrest Mims and also /Electronics
for Dummies/ at the book store as well as various internet sources for
additional information. Some sources claim /The Art of Electronics/ is
a necessity while others say it has entirely too much information and
the wrong approach for a hobbyist. I don't want to just build pre-made
kits or copy other people schematics -- I'd really like to make new and
original things happen. I have plenty ideas, but I seem to be stuck in
the CS / software point of view when it comes to construction. I can
build an entire program in my head for the aforementioned sample rate
reducer, but I just can't see envision it in components. I assume I'd
need some sort of analog signal to digital signal converter and an IC
chip to do the real work of the problem... but I really have no idea.
I already have some preliminary equipment (solder iron, desoldering
braid, thin pliers & cutters, wire stripper, 20 AWG solid wire, digital
multimeter, etc) but no actual components or breadboard. At this point
I am sort of sold on the dead-bug style for educational / experimental
prototyping.
So does anyone have any suggestions for me at all in anything I've
mentioned? I find myself wanting an expert electronics guy around to
guide me, but I don't know anyone, so I turn to internet folk. Any
material to read, sources to look up, comments regarding /The Art of
Electronics/?
Thanks! |
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Puckdropper
electronics forum addict
Joined: 13 Sep 2005
Posts: 73
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| Posted: Thu Aug 10, 2006 9:10 am Post subject:
Re: Suggestions for aspiring hobbyist
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sly.psi@gmail.com wrote in news:1155196425.535182.116970@
75g2000cwc.googlegroups.com:
| Quote: | There must be a million of these posts on this group and I apologize in
advance if I'm violating some rule.
I come from a computer science background and I'm now looking to get
into electronics as a hobby.
|
*snip*
Same with me. I *know* what makes a computer tick. ;-)
*snip*
| Quote: | I don't want to just build pre-made
kits or copy other people schematics -- I'd really like to make new and
original things happen. I have plenty ideas, but I seem to be stuck in
the CS / software point of view when it comes to construction. I can
build an entire program in my head for the aforementioned sample rate
reducer, but I just can't see envision it in components. I assume I'd
need some sort of analog signal to digital signal converter and an IC
chip to do the real work of the problem... but I really have no idea.
|
Electronic design seems to be able to be done like some software design.
Learn what the little parts do (fprintf, streams, etc) and put them
together.
| Quote: | I already have some preliminary equipment (solder iron, desoldering
braid, thin pliers & cutters, wire stripper, 20 AWG solid wire, digital
multimeter, etc) but no actual components or breadboard. At this point
I am sort of sold on the dead-bug style for educational / experimental
prototyping.
|
Look in to a starter kit. Avoid the Radio Shack 120-in-one ones, though,
they're ok, but not half as fun as playing with a handful of parts. Look
for digital logic chips in the kit, too. With your background, they
might be the things you understand first.
| Quote: | So does anyone have any suggestions for me at all in anything I've
mentioned? I find myself wanting an expert electronics guy around to
guide me, but I don't know anyone, so I turn to internet folk. Any
material to read, sources to look up, comments regarding /The Art of
Electronics/?
|
Learn to solder. Learn to unsolder. Practice, practice, practice.
You'll get some places where your soldering skills will be necessary to
prevent wrecking a $8 chip...
You're welcome.
Puckdropper
--
Wise is the man who attempts to answer his question before asking it.
To email me directly, send a message to puckdropper (at) fastmail.fm |
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default
electronics forum Guru Wannabe
Joined: 03 May 2005
Posts: 175
|
| Posted: Thu Aug 10, 2006 9:13 am Post subject:
Re: Suggestions for aspiring hobbyist
|
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|
On 10 Aug 2006 00:53:45 -0700, sly.psi@gmail.com wrote:
| Quote: | There must be a million of these posts on this group and I apologize in
advance if I'm violating some rule.
I come from a computer science background and I'm now looking to get
into electronics as a hobby. I have a few ideas for circuits I'd like
to construct eventually, most of which revolve around various sensors
and audio processing. One specific circuit I'd like to build a sample
& bit rate reducer for an electric guitar or bass signal with a
CV-controlled LFO to control the intensity of the effect.
Anyway, I've been reading books by Forrest Mims and also /Electronics
for Dummies/ at the book store as well as various internet sources for
additional information. Some sources claim /The Art of Electronics/ is
a necessity while others say it has entirely too much information and
the wrong approach for a hobbyist. I don't want to just build pre-made
kits or copy other people schematics -- I'd really like to make new and
original things happen. I have plenty ideas, but I seem to be stuck in
the CS / software point of view when it comes to construction. I can
build an entire program in my head for the aforementioned sample rate
reducer, but I just can't see envision it in components. I assume I'd
need some sort of analog signal to digital signal converter and an IC
chip to do the real work of the problem... but I really have no idea.
I already have some preliminary equipment (solder iron, desoldering
braid, thin pliers & cutters, wire stripper, 20 AWG solid wire, digital
multimeter, etc) but no actual components or breadboard. At this point
I am sort of sold on the dead-bug style for educational / experimental
prototyping.
So does anyone have any suggestions for me at all in anything I've
mentioned? I find myself wanting an expert electronics guy around to
guide me, but I don't know anyone, so I turn to internet folk. Any
material to read, sources to look up, comments regarding /The Art of
Electronics/?
Thanks!
|
Read some theory, build some kits. (what is the hangup with kits?
too demeaning to follow someone's lead?) Electronics is usually
taught by theory along with building some circuit that supports the
theory.
Do what interests you. There is no one book that is magic, and no one
approach that will be right for everyone.
You seem to be looking for a shortcut that will catapult you from zero
to master designer - probably won't happen that way - electronics
encompasses a lot of knowledge. No one is expert in all of it.
----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
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lmcgill2@uiuc.edu
electronics forum beginner
Joined: 20 Apr 2006
Posts: 26
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| Posted: Thu Aug 10, 2006 1:14 pm Post subject:
Re: DAC selection.
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Rich Grise wrote:
| Quote: | On Wed, 09 Aug 2006 06:38:31 -0700, lmcgill wrote:
Hello All, I have a DC motor that I want to control its speed. The way
I want to do it is by sending a digital signal from my PC to a DAC and
then use that voltage to control some PWM circuit. I need help
selecting an easy-to-use DAC IC. I would love at least 12 bits of
resolution. Anyway, thanks for any reccomendations. Lucas.
That sounds a little silly.
You already have a processor, why not just have it generate your PWM?
What is it, really, that you're trying to accomplish?
Good Luck!
Rich
|
Thanks for the replies. It's funny you both said the same thing and
that is that I was intending to do. I am intending on applying this to
a CNC typ application- drive a spindle DC motor and 3 or so stepper
motors (each needing PWM). I thought it would get pretty tricky to do
all that from one machine. I thought it would be easier to let a
sparate circuit control the spindle motor and my PC to control the
steppers. Does this sound like I'm on the right track or do you still
feel that it would be possible to control all 4 motors (4 different PWM
signals) from one PC? Any more input would be fantastic-Lucas. |
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John Popelish
electronics forum Guru
Joined: 29 Apr 2005
Posts: 1601
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| Posted: Thu Aug 10, 2006 1:16 pm Post subject:
Re: Why Collector ??
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DJ Delorie wrote:
| Quote: | John Popelish <jpopelish@rica.net> writes:
A junction transistor is a heat operated device. They don't work
near absolute zero temperature.
Do FETs? My guess is yes.
|
Mine, too. Fets operate on a completely different principle
(modulation of channel conductivity by intrusion of transverse
electric field). But very weird things happen close to absolute zero
(superconductivity, for instance) that might interfere.
The main problem is the differential expansion (contraction) of
different materials that causes stress that might break something as
the device is cooled. |
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