relay closes but wont reopen
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Posts: 46,084
Hi All,
While relays are fresh in everyones mind, I have been trying to solve my
problem with a relay stamp circuit.....I am using a BS2 in a super carrier
board, a NP2222A transistor from Rshack with a N4001 diode across the
coils....the relay is a 5VDC reed relay Rshack p# 275-232.........everything
works fine untill I try to turn the relay off and turn out the light (60
watt bulb)....the relay stays closed (lit) untill I disassemble the relay
and it somehow magically "breaks loose" and I am able to do it over again.
Nothing seems to be damaged, I have checked with a meter and the output
pins on the stamp are behaving normally ( giving 0V or +5V at the expected
times ) so I guess Im asking " has anyone seen a relay stick like this,
and how do I stop it?"
I appreciate any suggestions.....but what I lay awake at night hoping for
is for someone to run down a list of parts and instructions for doing relays
correctly....I have 5-7 different relays and have tried them all, this is
as far as I've gotten.
My goal is to switch 400W AC reliably and safely with a stamp
Dave
While relays are fresh in everyones mind, I have been trying to solve my
problem with a relay stamp circuit.....I am using a BS2 in a super carrier
board, a NP2222A transistor from Rshack with a N4001 diode across the
coils....the relay is a 5VDC reed relay Rshack p# 275-232.........everything
works fine untill I try to turn the relay off and turn out the light (60
watt bulb)....the relay stays closed (lit) untill I disassemble the relay
and it somehow magically "breaks loose" and I am able to do it over again.
Nothing seems to be damaged, I have checked with a meter and the output
pins on the stamp are behaving normally ( giving 0V or +5V at the expected
times ) so I guess Im asking " has anyone seen a relay stick like this,
and how do I stop it?"
I appreciate any suggestions.....but what I lay awake at night hoping for
is for someone to run down a list of parts and instructions for doing relays
correctly....I have 5-7 different relays and have tried them all, this is
as far as I've gotten.
My goal is to switch 400W AC reliably and safely with a stamp
Dave
Comments
the relay is rated for 1 amp, I'm willing to bet this is a generous rating.
Might try something like their 900-2334 -- unfortunately, not available in
stores. It has a 5 amp rating on the contacts.
Original Message
> While relays are fresh in everyones mind, I have been trying to solve my
> problem with a relay stamp circuit.....I am using a BS2 in a super
carrier
> board, a NP2222A transistor from Rshack with a N4001 diode across the
> coils....the relay is a 5VDC reed relay Rshack p#
275-232.........everything
> works fine untill I try to turn the relay off and turn out the light (60
> watt bulb)....the relay stays closed (lit) untill I disassemble the relay
> and it somehow magically "breaks loose" and I am able to do it over
again.
> Nothing seems to be damaged, I have checked with a meter and the output
> pins on the stamp are behaving normally ( giving 0V or +5V at the
expected
> times ) so I guess Im asking " has anyone seen a relay stick like this,
> and how do I stop it?"
Believe you have arcing problems which are welding the contacts shut
(closed). Check out products by Opto 22 and the like which are used in the
industrial marketplace. Burt
>problem with a relay stamp circuit.....I am using a BS2 in a super carrier
>board, a NP2222A transistor from Rshack with a N4001 diode across the
>coils....the relay is a 5VDC reed relay Rshack p#
>275-232.........everything
>works fine untill I try to turn the relay off and turn out the light (60
>watt bulb)....the relay stays closed (lit) untill I disassemble the relay
>and it somehow magically "breaks loose" and I am able to do it over again.
>Nothing seems to be damaged, I have checked with a meter and the output
>pins on the stamp are behaving normally ( giving 0V or +5V at the expected
>times ) so I guess Im asking " has anyone seen a relay stick like this,
>and how do I stop it?"
I've seen relay contacts weld shut when they try to interrupt more current
than they are rated for. DC interruption is harder than with AC current. You
mentioned a 60W light bulb, which I presume is 120 Vac. My suggestion would
be to try a relay rated specifically for 120/240 Vac operation on the
contacts. A 12 Vdc coil is common in this configuration. I doubt the reed
relay is adequate for this task.
Rob
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> >While relays are fresh in everyones mind, I have been trying to solve my
> >problem with a relay stamp circuit.....I am using a BS2 in a super carrier
> >board, a NP2222A transistor from Rshack with a N4001 diode across the
> >coils....the relay is a 5VDC reed relay Rshack p#
> >275-232.........everything
> >works fine untill I try to turn the relay off and turn out the light (60
> >watt bulb)....the relay stays closed (lit) untill I disassemble the relay
> >and it somehow magically "breaks loose" and I am able to do it over again.
> >Nothing seems to be damaged, I have checked with a meter and the output
> >pins on the stamp are behaving normally ( giving 0V or +5V at the expected
> >times ) so I guess Im asking " has anyone seen a relay stick like this,
> >and how do I stop it?"
>
>I've seen relay contacts weld shut when they try to interrupt more current
>than they are rated for. DC interruption is harder than with AC current. You
>mentioned a 60W light bulb, which I presume is 120 Vac. My suggestion would
>be to try a relay rated specifically for 120/240 Vac operation on the
>contacts. A 12 Vdc coil is common in this configuration. I doubt the reed
>relay is adequate for this task.
>
>Rob
Are you sure your transistor is ok, and didn't (or doesn't) get zapped under
the load of the relay? Try removing the transistor and place a switch in its
place to energize the relay manually. If the relay shows similar signs and
arching is thought to blame, try placing a .01uF to .1uF Disc capacitor across
the relay terminals corresponding with the "sticky contacts".
Beau Schwabe IC Mask Designer
National Semiconductor Network Products Division
500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
together again (see A) or that you simply disconnect the relay from the
circuit (see
A) You might be "welding" the contacts. The data sheet
http://www.radioshack.com/SupportGate.asp?SupportPage=%2Fsupport%5Fsupplies%
2Fdoc35%2F35144%2Ehtm says that the contacts are rated at 1 watt, you say
that your using a 60 watt bulb. If you want to switch 400 watts AC, you
will need a relay with contacts rated at least for that.
that any coil voltage above 1/2 volt will keep the coil energized once the
initial contact closure has taken place.
If you have a specific relay question, don't hesitate to contact me, on- or
off-list.
Regards,
Daniel McGlothin
Original Message
From: samhell@s... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=ILAXWoNrBNZOXfeIFzUWCzjrAAGXlLxLsz0ZYKFfnkVNyXqh7znJx48_tZdNFB4zjJNqNnyxFH2sTi19]samhell@s...[/url
Sent: Thursday, March 01, 2001 12:38 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] relay closes but wont reopen
Hi All,
While relays are fresh in everyones mind, I have been trying to solve my
problem with a relay stamp circuit.....I am using a BS2 in a super carrier
board, a NP2222A transistor from Rshack with a N4001 diode across the
coils....the relay is a 5VDC reed relay Rshack p# 275-232.........everything
works fine untill I try to turn the relay off and turn out the light (60
watt bulb)....the relay stays closed (lit) untill I disassemble the relay
and it somehow magically "breaks loose" and I am able to do it over again.
Nothing seems to be damaged, I have checked with a meter and the output
pins on the stamp are behaving normally ( giving 0V or +5V at the expected
times ) so I guess Im asking " has anyone seen a relay stick like this,
and how do I stop it?"
I appreciate any suggestions.....but what I lay awake at night hoping for
is for someone to run down a list of parts and instructions for doing relays
correctly....I have 5-7 different relays and have tried them all, this is
as far as I've gotten.
My goal is to switch 400W AC reliably and safely with a stamp
Dave
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Just in case this hasn't been mentioned in this thread, I think the best
solution here would be to use a Solid State Relay (SSR). The "hockey-puck"
ones can typically switch up to 230 VAC at up to 10 amps or so. Cost is
$5-$15 depending on buying used/new. The control voltage is typically
anywhere from 3 to 30 VDC at a few milliamps.
Steve
Steve Roberts: sroberts@s...
I don't get to look at this list often, but happened to see your
question tonight. Your relay does sound a bit light - No pun
intended. Incandescent lamps will draw an inrush current about 6
times normal current. Light switches used to be "T-rated" (for
tungsten filament lamps) for this reason. You should select the
current capacity accordingly.
One possibility I did not see mentioned is that residual
magnetism
might be holding your relay closed. Once you pull it open by hand it
will be OK until it is again energized. An easy fix is to glue a
thin
piece of paper onto the magnetic armature or pole, to prevent
metal-to-metal contact of the armature. Note that I don't mean the
contacts, but the iron parts. This will allow the relay to drop out
easily once the coil is deenergized.
Best wishes,
Steve Bartlett
--- In basicstamps@au.egroups.com, samhell@s... wrote:
> Hi All,
>
> While relays are fresh in everyones mind, I have been trying to
solve my
> problem with a relay stamp circuit.....I am using a BS2 in a super
carrier
> board, a NP2222A transistor from Rshack with a N4001 diode across
the
> coils....the relay is a 5VDC reed relay Rshack p#
275-232.........everything
> works fine untill I try to turn the relay off and turn out the
light (60
> watt bulb)....the relay stays closed (lit) untill I disassemble the
relay
> and it somehow magically "breaks loose" and I am able to do it
over
again.
> Nothing seems to be damaged, I have checked with a meter and the
output
> pins on the stamp are behaving normally ( giving 0V or +5V at the
expected
> times ) so I guess Im asking " has anyone seen a relay stick like
this,
> and how do I stop it?"
>
> I appreciate any suggestions.....but what I lay awake at night
hoping for
> is for someone to run down a list of parts and instructions for
doing relays
> correctly....I have 5-7 different relays and have tried them all,
this is
> as far as I've gotten.
>
> My goal is to switch 400W AC reliably and safely with a stamp
>
>
>
> Dave
I think, as many suggested, you may have been experiencing sticking
contacts. This would most likely be a result of the contacts arcing and
"welding" themselves closed. Reed relays don't take much force stay closed.
I don't think that a 400W resistive load should be handled with a reed
relay, though. Try solid state relay (page 541 of the current Digikey
catalog) that is rated for your load.
Mike
>My goal is to switch 400W AC reliably and safely with a stamp
_______________________________________
Mike Walsh (mwalshelec@a...)
MWE
1322 W. Windsor Dr.
San Dimas, CA 91773
909-592-5881