5VDC Reed Relay
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Posts: 46,084
An easy question from a beginner:
I just purchased a 5VDC Reed Relay from radio shack (275-232).
I just want to know the best way to wire this to the stamp without
damaging it. I am assuming I need to wire the stamp to the coil
connections and the other wires go to the circuit I want to switch on
and off. Is this correct? How should I do it safely?
I just want to use the stamp to control a second independent circuit.
Thank You
Mike
I just purchased a 5VDC Reed Relay from radio shack (275-232).
I just want to know the best way to wire this to the stamp without
damaging it. I am assuming I need to wire the stamp to the coil
connections and the other wires go to the circuit I want to switch on
and off. Is this correct? How should I do it safely?
I just want to use the stamp to control a second independent circuit.
Thank You
Mike
Comments
Connect one coil terminal to +5 VDC. Connect the other coil terminal to the
collector of the 2n2222. Connect the emitter of the 2N2222 to ground.
Connect the base of the 2N2222 to one leg of a 10k resistor and connect the
other leg of the resistor to the stamp pin.
Original Message
> I just purchased a 5VDC Reed Relay from radio shack (275-232).
> I just want to know the best way to wire this to the stamp without
> damaging it. I am assuming I need to wire the stamp to the coil
> connections and the other wires go to the circuit I want to switch on
> and off. Is this correct? How should I do it safely?
>
> I just want to use the stamp to control a second independent circuit.
"backwards" across the coil. Put the banded end towards +5V and the
non-banded end to the collector side. This will absorb reverse spikes in the
coil before they can kill the transistor.
The voltage developed is almost entirely a function of the speed of the
switching, so you can get some large (short duration) voltages (this is the
same idea behind a spark gap, ignition coil, etc.).
Al Williams
AWC
* New PAK-IX floating point A/D: http://www.al-williams.com/awce/pak9.htm
>
Original Message
> From: Rodent [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=Cz4ILQNQejBOazEfgpqwX16pbGQfqFsPdwZIuLT3BGuvDtQ52Dzxl9DBFN4csVz04EiztmUOaZLg-A]daweasel@s...[/url
> Sent: Friday, April 13, 2001 9:49 PM
> To: basicstamps@yahoogroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] 5VDC Reed Relay
>
>
> You need to drive the relay with a transistor. A 2N2222 works OK.
>
> Connect one coil terminal to +5 VDC. Connect the other coil
> terminal to the
> collector of the 2n2222. Connect the emitter of the 2N2222 to ground.
> Connect the base of the 2N2222 to one leg of a 10k resistor and
> connect the
> other leg of the resistor to the stamp pin.
>
>
Original Message
>
> > I just purchased a 5VDC Reed Relay from radio shack (275-232).
> > I just want to know the best way to wire this to the stamp without
> > damaging it. I am assuming I need to wire the stamp to the coil
> > connections and the other wires go to the circuit I want to switch on
> > and off. Is this correct? How should I do it safely?
> >
> > I just want to use the stamp to control a second independent circuit.
>
>
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
microcontroller. The diode is important to protect the microcontroller from a
current surge when you turn the relay off and the magnetic field in the coil
collapses.
http://www.seattlerobotics.org/encoder/aug99/ballbot.html
You wrote:
I just purchased a 5VDC Reed Relay from radio shack (275-232).
I just want to know the best way to wire this to the stamp without
damaging it. I am assuming I need to wire the stamp to the coil
connections and the other wires go to the circuit I want to switch on
and off. Is this correct? How should I do it safely?
have fun-build robots
===========
Larry Geib
ljgeib@a...
===========
will die a quick, violent death. When the transistor turns off the
magnetic field in the relay coil collapses. This would appear as a
(possibly) large voltage spike across the transistor.
Easiest thing to do:
place a 1N4007 diode across the relay coil, anode towards the 2n2222
collector.
Ciao
Richard
--- In basicstamps@y..., Rodent <daweasel@s...> wrote:
> You need to drive the relay with a transistor. A 2N2222 works OK.
>
> Connect one coil terminal to +5 VDC. Connect the other coil
terminal to the
> collector of the 2n2222. Connect the emitter of the 2N2222 to
ground.
> Connect the base of the 2N2222 to one leg of a 10k resistor and
connect the
> other leg of the resistor to the stamp pin.
>
>
Original Message
>
> > I just purchased a 5VDC Reed Relay from radio shack (275-
232).
> > I just want to know the best way to wire this to the stamp without
> > damaging it. I am assuming I need to wire the stamp to the coil
> > connections and the other wires go to the circuit I want to
switch on
> > and off. Is this correct? How should I do it safely?
> >
> > I just want to use the stamp to control a second independent
circuit.
without. As a rule, I use them, but it was the wee hours when I wrote the
reply and it slipped my mind.
Original Message
> If the relay coil does not have a snubber across it the transistor
> will die a quick, violent death. When the transistor turns off the
> magnetic field in the relay coil collapses. This would appear as a
> (possibly) large voltage spike across the transistor.
>
> Easiest thing to do:
>
> place a 1N4007 diode across the relay coil, anode towards the 2n2222
> collector.
>
> Ciao
>
> Richard
>
>
> --- In basicstamps@y..., Rodent <daweasel@s...> wrote:
> > You need to drive the relay with a transistor. A 2N2222 works OK.
> >
> > Connect one coil terminal to +5 VDC. Connect the other coil
> terminal to the
> > collector of the 2n2222. Connect the emitter of the 2N2222 to
> ground.
> > Connect the base of the 2N2222 to one leg of a 10k resistor and
> connect the
> > other leg of the resistor to the stamp pin.
> >
> >
Original Message
> >
> > > I just purchased a 5VDC Reed Relay from radio shack (275-
> 232).
> > > I just want to know the best way to wire this to the stamp without
> > > damaging it. I am assuming I need to wire the stamp to the coil
> > > connections and the other wires go to the circuit I want to
> switch on
> > > and off. Is this correct? How should I do it safely?
> > >
> > > I just want to use the stamp to control a second independent
> circuit.
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
they have a part number. Question: What kind of problems can occur if I use
such a generic diode?
Dave
--- iceninevt@y... wrote:
> If the relay coil does not have a snubber across it the transistor
> will die a quick, violent death. When the transistor turns off the
> magnetic field in the relay coil collapses. This would appear as a
> (possibly) large voltage spike across the transistor.
>
> Easiest thing to do:
>
> place a 1N4007 diode across the relay coil, anode towards the 2n2222
> collector.
>
> Ciao
>
> Richard
>
>
> --- In basicstamps@y..., Rodent <daweasel@s...> wrote:
> > You need to drive the relay with a transistor. A 2N2222 works OK.
> >
> > Connect one coil terminal to +5 VDC. Connect the other coil
> terminal to the
> > collector of the 2n2222. Connect the emitter of the 2N2222 to
> ground.
> > Connect the base of the 2N2222 to one leg of a 10k resistor and
> connect the
> > other leg of the resistor to the stamp pin.
> >
> >
Original Message
> >
> > > I just purchased a 5VDC Reed Relay from radio shack (275-
> 232).
> > > I just want to know the best way to wire this to the stamp without
> > > damaging it. I am assuming I need to wire the stamp to the coil
> > > connections and the other wires go to the circuit I want to
> switch on
> > > and off. Is this correct? How should I do it safely?
> > >
> > > I just want to use the stamp to control a second independent
> circuit.
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
__________________________________________________
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Get email at your own domain with Yahoo! Mail.
http://personal.mail.yahoo.com/
they have a part number.· Question: What kind of problems canoccur if I use
such a generic diode?
Dave
--- iceninevt@yahoo.com wrote:
·
Generic stamp failure??· LOL!
Seriously though if the output is not properly protected by the diodeyou can seriously fry your stamp.
Rus
--
Rus Hardy
"Lucky Devil"
Atrophies - Ghoulishly Original Awards & Trophies
http://www.bluedestiny.com/Atrophies/
SpiderBucky & SpiderThrifty - Boney Superheroes
http://www.bluedestiny.com/SpiderBucky/
Keeper of the Bucky-n-Thrifty Flame
http://www.boneyardbargains.com/
"my mind wanders....I'm just along for the ride"
special diode for the reed relay protection? I don't think I phrased my
previous question correctly.
dave
--- Rus Hardy <rushardy@m...> wrote:
> david cousins wrote:
>
> > I recently bought a package of 20 diodes from Ratshack and I don't recall
> if
> > they have a part number. Question: What kind of problems can occur if I
> use
> > such a generic diode?
> > Dave
> > --- iceninevt@y... wrote:
> >
>
> Generic stamp failure?? LOL!
>
> Seriously though if the output is not properly protected by the diode you can
> seriously fry your stamp.
>
> Rus
>
>
> --
> Rus Hardy
> "Lucky Devil"
> Atrophies - Ghoulishly Original Awards & Trophies
> http://www.bluedestiny.com/Atrophies/
> SpiderBucky & SpiderThrifty - Boney Superheroes
> http://www.bluedestiny.com/SpiderBucky/
> Keeper of the Bucky-n-Thrifty Flame
> http://www.boneyardbargains.com/
> "my mind wanders....I'm just along for the ride"
>
>
__________________________________________________
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Get email at your own domain with Yahoo! Mail.
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be many times the voltage applied to it. The 1N4007 is a good choice,
I expect there will be a bunch of them in the RS diode bundle. The RS
diodes do have part numbers
Keep in mind that a speaker (not a piezo, a bona-fide voice coil type)
can damage a stamp, or a transistor, with equal ease as the relay
coil, for exactly the same reasons.
Placing a reverse-biased diode across an inductive load should be
considered an absololute necessity, every single time. There are
other ways of getting the job done, ie: a RC snubber, but I almost
always use the diode.
If you really want to protect your stamp consider coupling the stamp
output pin to the outside world using an optocoupler. They are not
difficult to use and afford the largest degree of protection to the
stamp.
Regards
Rich
--- In basicstamps@y..., david cousins <cuz_hsv@y...> wrote:
> I recently bought a package of 20 diodes from Ratshack and I don't
recall if
> they have a part number. Question: What kind of problems can occur
if I use
> such a generic diode?
> Dave
> --- iceninevt@y... wrote:
> > If the relay coil does not have a snubber across it the
transistor
> > will die a quick, violent death. When the transistor turns off
the
> > magnetic field in the relay coil collapses. This would appear as
a
> > (possibly) large voltage spike across the transistor.
> >
> > Easiest thing to do:
> >
> > place a 1N4007 diode across the relay coil, anode towards the
2n2222
> > collector.
> >
> > Ciao
> >
> > Richard
> >
> >
> > --- In basicstamps@y..., Rodent <daweasel@s...> wrote:
> > > You need to drive the relay with a transistor. A 2N2222 works
OK.
> > >
> > > Connect one coil terminal to +5 VDC. Connect the other coil
> > terminal to the
> > > collector of the 2n2222. Connect the emitter of the 2N2222 to
> > ground.
> > > Connect the base of the 2N2222 to one leg of a 10k resistor and
> > connect the
> > > other leg of the resistor to the stamp pin.
> > >
> > >
Original Message
> > >
> > > > I just purchased a 5VDC Reed Relay from radio shack (275-
> > 232).
> > > > I just want to know the best way to wire this to the stamp
without
> > > > damaging it. I am assuming I need to wire the stamp to the
coil
> > > > connections and the other wires go to the circuit I want to
> > switch on
> > > > and off. Is this correct? How should I do it safely?
> > > >
> > > > I just want to use the stamp to control a second independent
> > circuit.
> >
> >
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
>
>
> __________________________________________________
> Do You Yahoo!?
> Get email at your own domain with Yahoo! Mail.
> http://personal.mail.yahoo.com/
kind? I've used them with 5vdc relays in 2 different projects, one is
nearing 2 years run time without a problem. I've always put the black band
toward the +5v (if I remember correctly)
Robert Staph, W3RCS
The Center for Advanced Technologies
Original Message
From: david cousins <cuz_hsv@y...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, April 16, 2001 2:05 PM
Subject: Re: [noparse][[/noparse]basicstamps] Re: 5VDC Reed Relay
> Are you saying that I shouldn't use these generic diodes? That I need a
> special diode for the reed relay protection? I don't think I phrased my
> previous question correctly.
> dave
> --- Rus Hardy <rushardy@m...> wrote:
> > david cousins wrote:
> >
> > > I recently bought a package of 20 diodes from Ratshack and I don't
recall
> > if
> > > they have a part number. Question: What kind of problems can occur if
I
> > use
> > > such a generic diode?
> > > Dave
> > > --- iceninevt@y... wrote:
> > >
> >
> > Generic stamp failure?? LOL!
> >
> > Seriously though if the output is not properly protected by the diode
you can
> > seriously fry your stamp.
> >
> > Rus
> >
> >
> > --
> > Rus Hardy
> > "Lucky Devil"
> > Atrophies - Ghoulishly Original Awards & Trophies
> > http://www.bluedestiny.com/Atrophies/
> > SpiderBucky & SpiderThrifty - Boney Superheroes
> > http://www.bluedestiny.com/SpiderBucky/
> > Keeper of the Bucky-n-Thrifty Flame
> > http://www.boneyardbargains.com/
> > "my mind wanders....I'm just along for the ride"
> >
> >
>
>
> __________________________________________________
> Do You Yahoo!?
> Get email at your own domain with Yahoo! Mail.
> http://personal.mail.yahoo.com/
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
I am assuming since you are referring to them a "generic" diodes, and they do
not
have parts numbers on them and that you have no idea what "type" diodes they
are.....Is this correct?....
I would be afraid of using a "generic" diode (one for which you have no
information) in this case. Especially considering the cost of a stamp versus
the
cost of diodes.
I would spend the few cents and make sure I have a properly rated diode. I'm
using
(at the lists recommendation) the 1N4XXX series diodes and have had no problems.
ie... 1N4001, 1N4005, 1N4007.
Rus
david cousins wrote:
> Are you saying that I shouldn't use these generic diodes? That I need a
> special diode for the reed relay protection? I don't think I phrased my
> previous question correctly.
> dave
> --- Rus Hardy <rushardy@m...> wrote:
> > david cousins wrote:
> >
> > > I recently bought a package of 20 diodes from Ratshack and I don't recall
> > if
> > > they have a part number. Question: What kind of problems can occur if I
> > use
> > > such a generic diode?
> > > Dave
> > > --- iceninevt@y... wrote:
> > >
> >
> > Generic stamp failure?? LOL!
> >
> > Seriously though if the output is not properly protected by the diode you
can
> > seriously fry your stamp.
> >
> > Rus
> >
> >
--
Rus Hardy
"Lucky Devil"
Atrophies - Ghoulishly Original Awards & Trophies
http://www.bluedestiny.com/Atrophies/
SpiderBucky & SpiderThrifty - Boney Superheroes
http://www.bluedestiny.com/SpiderBucky/
Keeper of the Bucky-n-Thrifty Flame
http://www.boneyardbargains.com/
"my mind wanders....I'm just along for the ride"
With a resistor, we can measure resistance to voltage. Verification by
measuring voltage drop.
With a capacitor, we can store a large or small charge. Verification by
measuring voltage and a time delay.
Now how about these diodes. Keep in mind that I'm a civil engineer. What
differentiates one diode from another? Is it a measure of power?
Thanks in advance.
dave
--- iceninevt@y... wrote:
> The voltage spike created by the coils collapsing magnetic field can
> be many times the voltage applied to it. The 1N4007 is a good choice,
> I expect there will be a bunch of them in the RS diode bundle. The RS
> diodes do have part numbers
>
> Keep in mind that a speaker (not a piezo, a bona-fide voice coil type)
> can damage a stamp, or a transistor, with equal ease as the relay
> coil, for exactly the same reasons.
>
> Placing a reverse-biased diode across an inductive load should be
> considered an absololute necessity, every single time. There are
> other ways of getting the job done, ie: a RC snubber, but I almost
> always use the diode.
>
> If you really want to protect your stamp consider coupling the stamp
> output pin to the outside world using an optocoupler. They are not
> difficult to use and afford the largest degree of protection to the
> stamp.
>
> Regards
>
> Rich
>
> --- In basicstamps@y..., david cousins <cuz_hsv@y...> wrote:
> > I recently bought a package of 20 diodes from Ratshack and I don't
> recall if
> > they have a part number. Question: What kind of problems can occur
> if I use
> > such a generic diode?
> > Dave
> > --- iceninevt@y... wrote:
> > > If the relay coil does not have a snubber across it the
> transistor
> > > will die a quick, violent death. When the transistor turns off
> the
> > > magnetic field in the relay coil collapses. This would appear as
> a
> > > (possibly) large voltage spike across the transistor.
> > >
> > > Easiest thing to do:
> > >
> > > place a 1N4007 diode across the relay coil, anode towards the
> 2n2222
> > > collector.
> > >
> > > Ciao
> > >
> > > Richard
> > >
> > >
> > > --- In basicstamps@y..., Rodent <daweasel@s...> wrote:
> > > > You need to drive the relay with a transistor. A 2N2222 works
> OK.
> > > >
> > > > Connect one coil terminal to +5 VDC. Connect the other coil
> > > terminal to the
> > > > collector of the 2n2222. Connect the emitter of the 2N2222 to
> > > ground.
> > > > Connect the base of the 2N2222 to one leg of a 10k resistor and
> > > connect the
> > > > other leg of the resistor to the stamp pin.
> > > >
> > > >
Original Message
> > > >
> > > > > I just purchased a 5VDC Reed Relay from radio shack (275-
> > > 232).
> > > > > I just want to know the best way to wire this to the stamp
> without
> > > > > damaging it. I am assuming I need to wire the stamp to the
> coil
> > > > > connections and the other wires go to the circuit I want to
> > > switch on
> > > > > and off. Is this correct? How should I do it safely?
> > > > >
> > > > > I just want to use the stamp to control a second independent
> > > circuit.
> > >
> > >
> > >
> > >
> > > Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
> > >
> > >
> >
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Get email at your own domain with Yahoo! Mail.
> > http://personal.mail.yahoo.com/
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
__________________________________________________
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Thanks for the reply. I really enjoy this electronics stuff, and folks like
yourself, have helped me a bunch.
Dave
--- Robert Staph <rstaph@a...> wrote:
> I bought the same pack of diodes I think, small 2mm glass encapsulated
> kind? I've used them with 5vdc relays in 2 different projects, one is
> nearing 2 years run time without a problem. I've always put the black band
> toward the +5v (if I remember correctly)
>
> Robert Staph, W3RCS
> The Center for Advanced Technologies
>
>
>
Original Message
> From: david cousins <cuz_hsv@y...>
> To: <basicstamps@yahoogroups.com>
> Sent: Monday, April 16, 2001 2:05 PM
> Subject: Re: [noparse][[/noparse]basicstamps] Re: 5VDC Reed Relay
>
>
> > Are you saying that I shouldn't use these generic diodes? That I need a
> > special diode for the reed relay protection? I don't think I phrased my
> > previous question correctly.
> > dave
> > --- Rus Hardy <rushardy@m...> wrote:
> > > david cousins wrote:
> > >
> > > > I recently bought a package of 20 diodes from Ratshack and I don't
> recall
> > > if
> > > > they have a part number. Question: What kind of problems can occur if
> I
> > > use
> > > > such a generic diode?
> > > > Dave
> > > > --- iceninevt@y... wrote:
> > > >
> > >
> > > Generic stamp failure?? LOL!
> > >
> > > Seriously though if the output is not properly protected by the diode
> you can
> > > seriously fry your stamp.
> > >
> > > Rus
> > >
> > >
> > > --
> > > Rus Hardy
> > > "Lucky Devil"
> > > Atrophies - Ghoulishly Original Awards & Trophies
> > > http://www.bluedestiny.com/Atrophies/
> > > SpiderBucky & SpiderThrifty - Boney Superheroes
> > > http://www.bluedestiny.com/SpiderBucky/
> > > Keeper of the Bucky-n-Thrifty Flame
> > > http://www.boneyardbargains.com/
> > > "my mind wanders....I'm just along for the ride"
> > >
> > >
> >
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Get email at your own domain with Yahoo! Mail.
> > http://personal.mail.yahoo.com/
> >
> >
> >
> > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
> >
> >
> >
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
__________________________________________________
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500mA) which maps to a OEG brand model OMR-2-06-F relay. I can't tell
(although it certainly can be staring me in the face) from the relay
data sheet what the maximum reverse voltage produced from the coil could
be. http://www.oeg.com.cn/pdf/14_OMR.pdf
How would I go about calculating it to make sure my diode can handle it?
Thanks,
Kevin
david cousins wrote:
>
> Are you saying that I shouldn't use these generic diodes? That I need a
> special diode for the reed relay protection? I don't think I phrased my
> previous question correctly.
> dave
> --- Rus Hardy <rushardy@m...> wrote:
> > david cousins wrote:
> >
> > > I recently bought a package of 20 diodes from Ratshack and I don't recall
> > if
> > > they have a part number. Question: What kind of problems can occur if I
> > use
> > > such a generic diode?
> > > Dave
> > > --- iceninevt@y... wrote:
> > >
> >
> > Generic stamp failure?? LOL!
> >
> > Seriously though if the output is not properly protected by the diode you
can
> > seriously fry your stamp.
> >
> > Rus
> >
> >
> > --
> > Rus Hardy
> > "Lucky Devil"
> > Atrophies - Ghoulishly Original Awards & Trophies
> > http://www.bluedestiny.com/Atrophies/
> > SpiderBucky & SpiderThrifty - Boney Superheroes
> > http://www.bluedestiny.com/SpiderBucky/
> > Keeper of the Bucky-n-Thrifty Flame
> > http://www.boneyardbargains.com/
> > "my mind wanders....I'm just along for the ride"
> >
> >
>
> __________________________________________________
> Do You Yahoo!?
> Get email at your own domain with Yahoo! Mail.
> http://personal.mail.yahoo.com/
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
capacitor. The voltage drop across a diode (or most any) P/N junction
is 600mV (6/10 volt). Usually, this drop is constant, the drop does
not vary with changes in voltage.
There are many different types of diodes. They all do basically the
same thing, allow current flow in only one direction.
Some diodes are used for rectification, turning AC into DC. Others
are used for signal detection, etc.
The ratings that should concern you are:
PIV Peak Inverse Voltage. A diode will block current in one
direction, to a point. If to much voltage is appled to a diode, in
its non-conducting direction (reverse biased) the semiconductor
junction inside the diode "breaks down". The diode dies, (it usually
takes something with it.)
Zener diodes break down without dying, at a specific voltage. Zeners
are used to protect against overvoltage, and are often used to
produce a voltage reference.
Wattage How much power a diode can safely pass
Some diodes are required to conduct very quickly. Switching power
supplies use diodes that conduct very quickly to protect the output
devices. Stepper motor drivers are usually protected by these fast
diodes.
More information than you need? You bet!
Hope some of this helps.
Good Luck
Rich
http://geocities.com/rbc1956
--- In basicstamps@y..., david cousins <cuz_hsv@y...> wrote:
> It's me again, with another version of the diode question:
> With a resistor, we can measure resistance to voltage.
Verification by
> measuring voltage drop.
> With a capacitor, we can store a large or small charge.
Verification by
> measuring voltage and a time delay.
> Now how about these diodes. Keep in mind that I'm a civil
engineer. What
> differentiates one diode from another? Is it a measure of power?
>
> Thanks in advance.
> dave
>
> --- iceninevt@y... wrote:
> > The voltage spike created by the coils collapsing magnetic field
can
> > be many times the voltage applied to it. The 1N4007 is a good
choice,
> > I expect there will be a bunch of them in the RS diode bundle.
The RS
> > diodes do have part numbers
> >
> > Keep in mind that a speaker (not a piezo, a bona-fide voice coil
type)
> > can damage a stamp, or a transistor, with equal ease as the relay
> > coil, for exactly the same reasons.
> >
> > Placing a reverse-biased diode across an inductive load should be
> > considered an absololute necessity, every single time. There are
> > other ways of getting the job done, ie: a RC snubber, but I
almost
> > always use the diode.
> >
> > If you really want to protect your stamp consider coupling the
stamp
> > output pin to the outside world using an optocoupler. They are
not
> > difficult to use and afford the largest degree of protection to
the
> > stamp.
> >
> > Regards
> >
> > Rich
> >
> > --- In basicstamps@y..., david cousins <cuz_hsv@y...> wrote:
> > > I recently bought a package of 20 diodes from Ratshack and I
don't
> > recall if
> > > they have a part number. Question: What kind of problems can
occur
> > if I use
> > > such a generic diode?
> > > Dave
> > > --- iceninevt@y... wrote:
> > > > If the relay coil does not have a snubber across it the
> > transistor
> > > > will die a quick, violent death. When the transistor turns
off
> > the
> > > > magnetic field in the relay coil collapses. This would appear
as
> > a
> > > > (possibly) large voltage spike across the transistor.
> > > >
> > > > Easiest thing to do:
> > > >
> > > > place a 1N4007 diode across the relay coil, anode towards the
> > 2n2222
> > > > collector.
> > > >
> > > > Ciao
> > > >
> > > > Richard
> > > >
> > > >
> > > > --- In basicstamps@y..., Rodent <daweasel@s...> wrote:
> > > > > You need to drive the relay with a transistor. A 2N2222
works
> > OK.
> > > > >
> > > > > Connect one coil terminal to +5 VDC. Connect the other coil
> > > > terminal to the
> > > > > collector of the 2n2222. Connect the emitter of the 2N2222
to
> > > > ground.
> > > > > Connect the base of the 2N2222 to one leg of a 10k resistor
and
> > > > connect the
> > > > > other leg of the resistor to the stamp pin.
> > > > >
> > > > >
Original Message
> > > > >
> > > > > > I just purchased a 5VDC Reed Relay from radio shack
(275-
> > > > 232).
> > > > > > I just want to know the best way to wire this to the
stamp
> > without
> > > > > > damaging it. I am assuming I need to wire the stamp to
the
> > coil
> > > > > > connections and the other wires go to the circuit I want
to
> > > > switch on
> > > > > > and off. Is this correct? How should I do it safely?
> > > > > >
> > > > > > I just want to use the stamp to control a second
independent
> > > > circuit.
> > > >
> > > >
> > > >
> > > >
> > > > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> > > >
> > > >
> > >
> > >
> > > __________________________________________________
> > > Do You Yahoo!?
> > > Get email at your own domain with Yahoo! Mail.
> > > http://personal.mail.yahoo.com/
> >
> >
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
>
>
> __________________________________________________
> Do You Yahoo!?
> Get email at your own domain with Yahoo! Mail.
> http://personal.mail.yahoo.com/
Well there are several important diode parameters. First, the forward
voltage drop. If the material is silicon (1N914, 1N4148, 1N4XXX...) the drop
will be about .7V. Some meters can measure this directly with a "diode"
position. Otherwise, put a battery, a resistor, and a diode in series and
measure it with a voltmeter. Germanium drops about .3V. Hot carrier and
Schottky diodes have different forward voltages too.
The next big thing is the reverse breakdown voltage. If you put a big
voltage backwards, the diode may emit its internal smoke :-) This is often
rated as PIV "Peak Inverse Voltage". Diodes with very precise reverse
breakdowns are used as zener diodes.
The forward current capacity is another important parameter.
In some diodes, the junction capacitance is controlled and used as a voltage
variable capacitor. As the depletion region grows and shrinks the
capacitance changes.
There are many special-purpose diodes made to switch, rectify, regulate,
etc. So the critical parameters change depending on what kind of diode you
want and why you want it.
The snub as discussed in the list is pretty non-critical because the reverse
voltage has very little duration or current. Almost any diode will safely
short it to ground.
However, in some cases, diode selection is critical. For example, if you
were building a crystal-type radio, you'd want to use a Germanium diode so
you could hear weaker signals. If you were using diodes to switch an
antenna, you'd want fast switching diodes with controlled capacitance.
One size doesn't fit all :-)
BTW, if the Radio Shack bag 'o diodes are clear glass passivated (a clear
see through case) they are probably Germanium (1N34A? diodes). Not great for
logic use. Would probably work for the snub, but not my first choice.
If they are small glass with a reddish body, they are probably 1N914 or
1N4148 which would be OK. These are about the size of an 1/8W resistor. The
1N34's are about half between 1/4 and 1/2W size. The '914/'4148 is the
classic "logic" diode. Fast switching.
If they are black they are probably 1N4XXX but these are usually marked, at
least with the last digits (4001 for example). These are OK too. Usually
used in power supplies.
This is all from memory. Someone will correct me if I'm wrong.
Regards,
Al Williams
AWC
*Floating point A/D: http://www.al-williams.com/awce/pak9.htm
>
Original Message
> From: david cousins [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=S46Lku8lTS363Z2JE72Awvoojtt0JP1EfI4PWnZpXoCGvKwZdDLR92CyjPRXqHHPdD9tILFg6A]cuz_hsv@y...[/url
> Sent: Monday, April 16, 2001 1:39 PM
> To: basicstamps@yahoogroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] Re: 5VDC Reed Relay
>
>
> It's me again, with another version of the diode question:
> With a resistor, we can measure resistance to voltage. Verification by
> measuring voltage drop.
> With a capacitor, we can store a large or small charge. Verification by
> measuring voltage and a time delay.
> Now how about these diodes. Keep in mind that I'm a civil engineer. What
> differentiates one diode from another? Is it a measure of power?
>
> Thanks in advance.
> dave
>
> --- iceninevt@y... wrote:
> > The voltage spike created by the coils collapsing magnetic field can
> > be many times the voltage applied to it. The 1N4007 is a good choice,
> > I expect there will be a bunch of them in the RS diode bundle. The RS
> > diodes do have part numbers
> >
> > Keep in mind that a speaker (not a piezo, a bona-fide voice coil type)
> > can damage a stamp, or a transistor, with equal ease as the relay
> > coil, for exactly the same reasons.
> >
> > Placing a reverse-biased diode across an inductive load should be
> > considered an absololute necessity, every single time. There are
> > other ways of getting the job done, ie: a RC snubber, but I almost
> > always use the diode.
> >
> > If you really want to protect your stamp consider coupling the stamp
> > output pin to the outside world using an optocoupler. They are not
> > difficult to use and afford the largest degree of protection to the
> > stamp.
> >
> > Regards
> >
> > Rich
> >
> > --- In basicstamps@y..., david cousins <cuz_hsv@y...> wrote:
> > > I recently bought a package of 20 diodes from Ratshack and I don't
> > recall if
> > > they have a part number. Question: What kind of problems can occur
> > if I use
> > > such a generic diode?
> > > Dave
> > > --- iceninevt@y... wrote:
> > > > If the relay coil does not have a snubber across it the
> > transistor
> > > > will die a quick, violent death. When the transistor turns off
> > the
> > > > magnetic field in the relay coil collapses. This would appear as
> > a
> > > > (possibly) large voltage spike across the transistor.
> > > >
> > > > Easiest thing to do:
> > > >
> > > > place a 1N4007 diode across the relay coil, anode towards the
> > 2n2222
> > > > collector.
> > > >
> > > > Ciao
> > > >
> > > > Richard
> > > >
> > > >
> > > > --- In basicstamps@y..., Rodent <daweasel@s...> wrote:
> > > > > You need to drive the relay with a transistor. A 2N2222 works
> > OK.
> > > > >
> > > > > Connect one coil terminal to +5 VDC. Connect the other coil
> > > > terminal to the
> > > > > collector of the 2n2222. Connect the emitter of the 2N2222 to
> > > > ground.
> > > > > Connect the base of the 2N2222 to one leg of a 10k resistor and
> > > > connect the
> > > > > other leg of the resistor to the stamp pin.
> > > > >
> > > > >
Original Message
> > > > >
> > > > > > I just purchased a 5VDC Reed Relay from radio shack (275-
> > > > 232).
> > > > > > I just want to know the best way to wire this to the stamp
> > without
> > > > > > damaging it. I am assuming I need to wire the stamp to the
> > coil
> > > > > > connections and the other wires go to the circuit I want to
> > > > switch on
> > > > > > and off. Is this correct? How should I do it safely?
> > > > > >
> > > > > > I just want to use the stamp to control a second independent
> > > > circuit.
> > > >
> > > >
> > > >
> > > >
> > > > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> > > >
> > > >
> > >
> > >
> > > __________________________________________________
> > > Do You Yahoo!?
> > > Get email at your own domain with Yahoo! Mail.
> > > http://personal.mail.yahoo.com/
> >
> >
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
>
>
__________________________________________________
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Get email at your own domain with Yahoo! Mail.
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Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
problem I foresee is getting a zener diode rather than a normal one. If the
zener is rated below 5 volts, it might conduct when you power the circuit
up.
Original Message
> I recently bought a package of 20 diodes from Ratshack and I don't recall
if
> they have a part number. Question: What kind of problems can occur if I
use
> such a generic diode?
Should work fine for a *small* relay like a reed relay or one of the DIP
relays. Yes, the banded end goes toward +5 VDC.
Original Message
> I bought the same pack of diodes I think, small 2mm glass encapsulated
> kind? I've used them with 5vdc relays in 2 different projects, one is
> nearing 2 years run time without a problem. I've always put the black
band
> toward the +5v (if I remember correctly)
> > Are you saying that I shouldn't use these generic diodes? That I need a
> > special diode for the reed relay protection? I don't think I phrased my
> > previous question correctly.
amount of voltage they will block in the reverse direction. The 1N4007
referred to previously is rated for one amp with a peak inverse voltage of
1000 volts.
If you want the specs, go to:
http://www.fairchildsemi.com/ds/1N/1N4007.pdf
Original Message
> It's me again, with another version of the diode question:
> With a resistor, we can measure resistance to voltage. Verification by
> measuring voltage drop.
> With a capacitor, we can store a large or small charge. Verification by
> measuring voltage and a time delay.
> Now how about these diodes. Keep in mind that I'm a civil engineer. What
> differentiates one diode from another? Is it a measure of power?
The diode only "works" when the relay is turned off, and then usually only
for a few hundred millisecs. What ratings does the diode need? When the
relay is on, the diode sees the coil voltage as a reverse stress, so a 12
volt relay would need a diode rated greater than 12 volts PIV, (peak inverse
voltage). When the relay is turned off, the diode will momentarily carry
whatever the relay coil current was. If it is a 500 ma coil, the diode
should be rated for 500 ma, (or more), forward current, (If).
Summary:
If >= coil current
PIV >= coil voltage.
The high voltages mentioned in this thread only occur without a diode. If
you use the generic diodes, and they are not rated for the coil current, the
diode will pop, you lose your protection, then the transistor dies. A
simple test, if you want to use the cheap diodes, is to connect the diode
across the power supply, band to positive. If it doesn't pop, it has a high
enough PIV. Now connect the diode in series with the relay and apply the
normal relay voltage + 0.7 volts. If the diode doesn't pop, it has an
adequate If.
Hope this helps,
Ray McArthur
> I recently bought a package of 20 diodes from Ratshack and I don't recall
if
> they have a part number. Question: What kind of problems can occur if I
use
> such a generic diode?
tag in the bottom of my parts bin. They are indeed the 1N914's.
Thanks to everyone for their inputs and teaching. Your responses have
provided me with numerous little learning tasks to cement these studies.
I also searched on the optoisolators and started learning about them. Of
course I immediately have questions. Hoping that I haven't already worn out my
welcome, I will ask it.
Does the optoisolator have an internal LED and Phototransisoter inside the
chip?
The switching is done with only light? Since no electricity is passed between
the circuits, they are isolated? If so, very cool.
Thanks again.
Dave
--- Rodent <daweasel@s...> wrote:
> *Usually* the glass ones are 1N914's -- a low-current general-purpose diode.
> Should work fine for a *small* relay like a reed relay or one of the DIP
> relays. Yes, the banded end goes toward +5 VDC.
>
>
Original Message
>
> > I bought the same pack of diodes I think, small 2mm glass encapsulated
> > kind? I've used them with 5vdc relays in 2 different projects, one is
> > nearing 2 years run time without a problem. I've always put the black
> band
> > toward the +5v (if I remember correctly)
>
> > > Are you saying that I shouldn't use these generic diodes? That I need a
> > > special diode for the reed relay protection? I don't think I phrased my
> > > previous question correctly.
>
>
__________________________________________________
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Yahoo! Auctions - buy the things you want at great prices
http://auctions.yahoo.com/
opto-isolator. These are typically used to isolate a low-voltage circuit
from a high-voltage circuit. We used them to drive 110 VAC relays with
logic-level signals.
You'll still probably have to use a transistor to drive the relay -- most
opto-isolators are very low current.
Original Message
> As many of you said, my diodes do have part numbers on them, and I did
save the
> tag in the bottom of my parts bin. They are indeed the 1N914's.
> Thanks to everyone for their inputs and teaching. Your responses have
> provided me with numerous little learning tasks to cement these studies.
>
> I also searched on the optoisolators and started learning about them. Of
> course I immediately have questions. Hoping that I haven't already worn
out my
> welcome, I will ask it.
>
> Does the optoisolator have an internal LED and Phototransisoter inside the
> chip?
> The switching is done with only light? Since no electricity is passed
between
> the circuits, they are isolated? If so, very cool.
The switching is done only with light. Inside the optoisolator
(photocoupler) is a LED and either a photodiode or phototransistor.
Opto's come in a ton of flavors...
Some are used as triac drivers. What this means is that your stamp
could switch an AC load (like your coffee maker or lights) with just
a small handful of parts, and without using a relay. Sometimes the
relay is a good choice, but is is a mechanical device, it is slow,
noisy, and being a mechanical device has a much shorter life than a
solid state switch (like a triac)
Opto's do many, many other things.
if these things interest you I would recommend you get a trial copy
of Nuts and Volts magazine (www.nutsvolts.com) and consider
subscribing.
I am a new "stamper", I got my BS2 three weeks ago. I have found NV
to be very stamp-friendly. A good source for electronics info, and
for stamp hints. I am 44 years old and my electronics education
stopped about 20 years ago, until three weeks ago, when I got my BS2.
It is never to late to learn. Good Luck
Regards
Rich
http://geocities.com/rbc1956
--- In basicstamps@y..., david cousins <cuz_hsv@y...> wrote:
> As many of you said, my diodes do have part numbers on them, and I
did save the
> tag in the bottom of my parts bin. They are indeed the 1N914's.
> Thanks to everyone for their inputs and teaching. Your responses
have
> provided me with numerous little learning tasks to cement these
studies.
>
> I also searched on the optoisolators and started learning about
them. Of
> course I immediately have questions. Hoping that I haven't already
worn out my
> welcome, I will ask it.
>
> Does the optoisolator have an internal LED and Phototransisoter
inside the
> chip?
> The switching is done with only light? Since no electricity is
passed between
> the circuits, they are isolated? If so, very cool.
> Thanks again.
> Dave
>
> --- Rodent <daweasel@s...> wrote:
> > *Usually* the glass ones are 1N914's -- a low-current general-
purpose diode.
> > Should work fine for a *small* relay like a reed relay or one of
the DIP
> > relays. Yes, the banded end goes toward +5 VDC.
> >
> >
Original Message
> >
> > > I bought the same pack of diodes I think, small 2mm glass
encapsulated
> > > kind? I've used them with 5vdc relays in 2 different projects,
one is
> > > nearing 2 years run time without a problem. I've always put
the black
> > band
> > > toward the +5v (if I remember correctly)
> >
> > > > Are you saying that I shouldn't use these generic diodes?
That I need a
> > > > special diode for the reed relay protection? I don't think I
phrased my
> > > > previous question correctly.
> >
> >
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Auctions - buy the things you want at great prices
> http://auctions.yahoo.com/
They really do protect a lot of sensitive electronics from high current
lines going to a motor. They also cut out any knid of noise that
motors will generate. Plus optical anything gives it a very high tech
ambience.
-Ryan
numbers that work well with stamps? I'm looking for smaller footprint
types, I've seen them in an 6 or 8 pin dip before. I'd be interested in
ones that could do 12vdc at around 1A, and ones that do 120vac at 1A.
Also simplicity of design is good too. If I don't need a farm of external
components, I'd love to start using them. Just never had any good leads on
ones that would match up well with stamps.
Robert Staph, W3RCS
The Center for Advanced Technologies
Computer Networking Consultant (CNC-DPT)
Original Message
From: <theryan@t...>
To: <basicstamps@yahoogroups.com>
Sent: Tuesday, April 17, 2001 4:11 PM
Subject: [noparse][[/noparse]basicstamps] Re: 5VDC Reed Relay
> Personally I like optos, I've used them alot in robot applications.
> They really do protect a lot of sensitive electronics from high current
> lines going to a motor. They also cut out any knid of noise that
> motors will generate. Plus optical anything gives it a very high tech
> ambience.
> -Ryan
>
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>