Power Supply (newbie) question.
Archiver
Posts: 46,084
The most likely to work in the short term is
to use a separate supply, WITH COMMON DC GROUNDS,
to drive each device.
It's likely the switching transient which is
pulling down VCC enough to reset the BS1. You
can maybe prevent this with a large capacitor
(100 uF) sitting close to the BS1, connected
to its +5 and GND leads. I'm assuming you
have read the 7805 docs, and have proper
capacitors on its input and outputs.
The most robust approach is to have one
supply whose purpose in life is to power
the BS1, and then another supply whose purpose
is to provide power to the motors and
solenoids, switched by the BS1 through
PNP (2n2222) transistors (or a ULN200x darlington
chip).
You definitely want some common ground reference
point for all power supplies used. This is all
low-voltage, TTL control stuff. Disconnected
grounds will give you wildly unpredictable
results.
--- In basicstamps@yahoogroups.com, Robert Rothe <rrothe@m...> wrote:
> I'm working on a BS-1 application to control some motors and
solenoids. I think I have a handle on the control portion of the
project (ie, relays, SSRs, etc). My question is 'how do you power
all this stuff easily?'
>
> The stamp is currently being run off of a wall-wart power supply
through a 7805. The motors draw a lot of current at bot 5 and 12
volts.
>
> I also have one solenoid that requires 24v AC 600ma. (which I'm
assuming I can probably run on 12 v DC).
>
> So, should I:
>
> a) try and find a wall-wart power supply that can deliver over 1
amp at 12V and just run the 12V through the 7085 for the stamp, too?
>
> b) Maybe use an old computer power supply since it can source 5 and
12 volts with higher currents? (I've googled this idea and think I
understand the "no-load" considerations)
>
> c) Use separate sources for each device? (ie, no common ground;
load devices controlled through either relays or SSRs)
>
>
> This problem came to light when I tried to run a 1.3v or 9v motor
though a relay controlled by the BS-1. I was trying to pull all the
power from the 7085 (or before the 7805 for the 9v loads) and the
stamp kept reseting when the motor was connected to the Normally Open
relay contact and the relay actived by the stamp. Oddly, it worked
OK on the Normally Closed contact. Lower current loads worked fine
on both, so I'm assuming I was overloading the 7805 or the power
supply. The DC power supply was a 12v 300ma or so radio shack
special. I don't know the exact amp rating on the small hobby motors.
>
>
> Any help and advice would be greatly appreciated. Cost is a
serious consideration. I'm new at this, so please type slow and
small :-)
>
> Rob
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
to use a separate supply, WITH COMMON DC GROUNDS,
to drive each device.
It's likely the switching transient which is
pulling down VCC enough to reset the BS1. You
can maybe prevent this with a large capacitor
(100 uF) sitting close to the BS1, connected
to its +5 and GND leads. I'm assuming you
have read the 7805 docs, and have proper
capacitors on its input and outputs.
The most robust approach is to have one
supply whose purpose in life is to power
the BS1, and then another supply whose purpose
is to provide power to the motors and
solenoids, switched by the BS1 through
PNP (2n2222) transistors (or a ULN200x darlington
chip).
You definitely want some common ground reference
point for all power supplies used. This is all
low-voltage, TTL control stuff. Disconnected
grounds will give you wildly unpredictable
results.
--- In basicstamps@yahoogroups.com, Robert Rothe <rrothe@m...> wrote:
> I'm working on a BS-1 application to control some motors and
solenoids. I think I have a handle on the control portion of the
project (ie, relays, SSRs, etc). My question is 'how do you power
all this stuff easily?'
>
> The stamp is currently being run off of a wall-wart power supply
through a 7805. The motors draw a lot of current at bot 5 and 12
volts.
>
> I also have one solenoid that requires 24v AC 600ma. (which I'm
assuming I can probably run on 12 v DC).
>
> So, should I:
>
> a) try and find a wall-wart power supply that can deliver over 1
amp at 12V and just run the 12V through the 7085 for the stamp, too?
>
> b) Maybe use an old computer power supply since it can source 5 and
12 volts with higher currents? (I've googled this idea and think I
understand the "no-load" considerations)
>
> c) Use separate sources for each device? (ie, no common ground;
load devices controlled through either relays or SSRs)
>
>
> This problem came to light when I tried to run a 1.3v or 9v motor
though a relay controlled by the BS-1. I was trying to pull all the
power from the 7085 (or before the 7805 for the 9v loads) and the
stamp kept reseting when the motor was connected to the Normally Open
relay contact and the relay actived by the stamp. Oddly, it worked
OK on the Normally Closed contact. Lower current loads worked fine
on both, so I'm assuming I was overloading the 7805 or the power
supply. The DC power supply was a 12v 300ma or so radio shack
special. I don't know the exact amp rating on the small hobby motors.
>
>
> Any help and advice would be greatly appreciated. Cost is a
serious consideration. I'm new at this, so please type slow and
small :-)
>
> Rob
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
Comments
allan.lane@h... writes:
> The most robust approach is to have one
> supply whose purpose in life is to power
> the BS1, and then another supply whose purpose
> is to provide power to the motors and
> solenoids, switched by the BS1 through
> PNP (2n2222) transistors (or a ULN200x darlington
> chip).
NPN (2n2222) - I am sure this was a simple mistake on your part, but for the
"beginners" a 2n2222 is an NPN device
>
> You definitely want some common ground reference
> point for all power supplies used. This is all
> low-voltage, TTL control stuff. Disconnected
> grounds will give you wildly unpredictable
> results.
[noparse][[/noparse]Non-text portions of this message have been removed]
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> In a message dated 7/10/2003 12:45:15 PM Pacific Daylight Time,
> allan.lane@h... writes:
>
> > The most robust approach is to have one
> > supply whose purpose in life is to power
> > the BS1, and then another supply whose purpose
> > is to provide power to the motors and
> > solenoids, switched by the BS1 through
> > PNP (2n2222) transistors (or a ULN200x darlington
> > chip).
>
> NPN (2n2222) - I am sure this was a simple mistake on your part,
but for the
> "beginners" a 2n2222 is an NPN device
>
> >
> > You definitely want some common ground reference
> > point for all power supplies used. This is all
> > low-voltage, TTL control stuff. Disconnected
> > grounds will give you wildly unpredictable
> > results.
>
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
wrote:
> Doh! Sorry about that.
>
> --- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> > In a message dated 7/10/2003 12:45:15 PM Pacific Daylight Time,
> > allan.lane@h... writes:
> >
> > > The most robust approach is to have one
> > > supply whose purpose in life is to power
> > > the BS1, and then another supply whose purpose
> > > is to provide power to the motors and
> > > solenoids, switched by the BS1 through
> > > PNP (2n2222) transistors (or a ULN200x darlington
> > > chip).
> >
> > NPN (2n2222) - I am sure this was a simple mistake on your part,
> but for the
> > "beginners" a 2n2222 is an NPN device
> >
> > >
> > > You definitely want some common ground reference
> > > point for all power supplies used. This is all
> > > low-voltage, TTL control stuff. Disconnected
> > > grounds will give you wildly unpredictable
> > > results.
> >
> >
> >
> > [noparse][[/noparse]Non-text portions of this message have been removed]
wrote:
> Doh! Sorry about that.
>
> --- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> > In a message dated 7/10/2003 12:45:15 PM Pacific Daylight Time,
> > allan.lane@h... writes:
> >
> > > The most robust approach is to have one
> > > supply whose purpose in life is to power
> > > the BS1, and then another supply whose purpose
> > > is to provide power to the motors and
> > > solenoids, switched by the BS1 through
> > > PNP (2n2222) transistors (or a ULN200x darlington
> > > chip).
> >
> > NPN (2n2222) - I am sure this was a simple mistake on your part,
> but for the
> > "beginners" a 2n2222 is an NPN device
> >
> > >
> > > You definitely want some common ground reference
> > > point for all power supplies used. This is all
> > > low-voltage, TTL control stuff. Disconnected
> > > grounds will give you wildly unpredictable
> > > results.
> >
> >
> >
> > [noparse][[/noparse]Non-text portions of this message have been removed]
I have a handle on the control portion of the project (ie, relays, SSRs, etc).
My question is 'how do you power all this stuff easily?'
The stamp is currently being run off of a wall-wart power supply through a 7805.
The motors draw a lot of current at bot 5 and 12 volts.
I also have one solenoid that requires 24v AC 600ma. (which I'm assuming I can
probably run on 12 v DC).
So, should I:
a) try and find a wall-wart power supply that can deliver over 1 amp at 12V and
just run the 12V through the 7085 for the stamp, too?
b) Maybe use an old computer power supply since it can source 5 and 12 volts
with higher currents? (I've googled this idea and think I understand the
"no-load" considerations)
c) Use separate sources for each device? (ie, no common ground; load devices
controlled through either relays or SSRs)
This problem came to light when I tried to run a 1.3v or 9v motor though a relay
controlled by the BS-1. I was trying to pull all the power from the 7085 (or
before the 7805 for the 9v loads) and the stamp kept reseting when the motor was
connected to the Normally Open relay contact and the relay actived by the stamp.
Oddly, it worked OK on the Normally Closed contact. Lower current loads worked
fine on both, so I'm assuming I was overloading the 7805 or the power supply.
The DC power supply was a 12v 300ma or so radio shack special. I don't know the
exact amp rating on the small hobby motors.
Any help and advice would be greatly appreciated. Cost is a serious
consideration. I'm new at this, so please type slow and small :-)
Rob
[noparse][[/noparse]Non-text portions of this message have been removed]
for a common ground among power supplies that are isolated via a mechanical
or solid state relay. Just to be clear, all the TTL stuff will be on a
single supply.
(sorry for the blank posts)
Rob
Original Message
From: "rrothe64" <rrothe@m...>
To: <basicstamps@yahoogroups.com>
Sent: Thursday, July 10, 2003 2:32 PM
Subject: [noparse][[/noparse]basicstamps] Re: Power Supply (newbie) question.
> --- In basicstamps@yahoogroups.com, "Allan Lane" <allan.lane@h...>
> wrote:
> > Doh! Sorry about that.
> >
> > --- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> > > In a message dated 7/10/2003 12:45:15 PM Pacific Daylight Time,
> > > allan.lane@h... writes:
> > >
> > > > The most robust approach is to have one
> > > > supply whose purpose in life is to power
> > > > the BS1, and then another supply whose purpose
> > > > is to provide power to the motors and
> > > > solenoids, switched by the BS1 through
> > > > PNP (2n2222) transistors (or a ULN200x darlington
> > > > chip).
> > >
> > > NPN (2n2222) - I am sure this was a simple mistake on your part,
> > but for the
> > > "beginners" a 2n2222 is an NPN device
> > >
> > > >
> > > > You definitely want some common ground reference
> > > > point for all power supplies used. This is all
> > > > low-voltage, TTL control stuff. Disconnected
> > > > grounds will give you wildly unpredictable
> > > > results.
> > >
> > >
> > >
> > > [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
> To UNSUBSCRIBE, just send mail to:
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Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
You mentioned a 24vac 600mA solenoid but didn't give any information about
the relay thats resetting your stamp. What are its requirements? What are
you switching it with (transistor, photorelay, ULN2x03?
The stamp pins can only source a small amount of power (an led for example).
If you're going directly to a relay pin then resetting the stamp is not only
inevitable, its a godsend - t should burn the poor thing out!
If not, what's between the stamp and the relay?
Also, whats the stats on the motor? I have here a ST35 2v unipolar stepper
motor that requires 60mA per winding. Right beside it is an AEG SO21 5v
bipolar stepper that requires 625mA per winding. Even though the ST35 is
over twice the voltage, my 300mA 12v wall wart drives it, my MCU. 4 leds and
a ULN2803 with power to burn. The 5V motor would burn it out in no time.
In other words, details man, details [noparse]:)[/noparse]
Original Message
From: "Robert Rothe" <rrothe@m...>
To: <basicstamps@yahoogroups.com>
Sent: Thursday, July 10, 2003 3:27 PM
Subject: [noparse][[/noparse]basicstamps] Power Supply (newbie) question.
> I'm working on a BS-1 application to control some motors and solenoids. I
think I have a handle on the control portion of the project (ie, relays,
SSRs, etc). My question is 'how do you power all this stuff easily?'
>
> The stamp is currently being run off of a wall-wart power supply through a
7805. The motors draw a lot of current at bot 5 and 12 volts.
>
> I also have one solenoid that requires 24v AC 600ma. (which I'm assuming I
can probably run on 12 v DC).
>
> So, should I:
>
> a) try and find a wall-wart power supply that can deliver over 1 amp at
12V and just run the 12V through the 7085 for the stamp, too?
>
> b) Maybe use an old computer power supply since it can source 5 and 12
volts with higher currents? (I've googled this idea and think I understand
the "no-load" considerations)
>
> c) Use separate sources for each device? (ie, no common ground; load
devices controlled through either relays or SSRs)
>
>
> This problem came to light when I tried to run a 1.3v or 9v motor though a
relay controlled by the BS-1. I was trying to pull all the power from the
7085 (or before the 7805 for the 9v loads) and the stamp kept reseting when
the motor was connected to the Normally Open relay contact and the relay
actived by the stamp. Oddly, it worked OK on the Normally Closed contact.
Lower current loads worked fine on both, so I'm assuming I was overloading
the 7805 or the power supply. The DC power supply was a 12v 300ma or so
radio shack special. I don't know the exact amp rating on the small hobby
motors.
>
>
> Any help and advice would be greatly appreciated. Cost is a serious
consideration. I'm new at this, so please type slow and small :-)
>
> Rob
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
etc. "ground" on a wall wart isn't ground - its the AC Neutral line. AC
neutral isn't ground either, its midpoint between two phases of an AC wave.
While normally pretty close to zero volt potential to "earth" ground, its
almost never exactly zero.
There should be a movement to eradicate the word "ground" from electronics.
We should all have to call it "neutral" or be flogged!
Well ok, maybe not flogged - but definately have the M&M sorter steal all
the reds from any packs we buy.
Original Message
From: "Robert Rothe" <rrothe@m...>
To: <basicstamps@yahoogroups.com>
Sent: Thursday, July 10, 2003 5:37 PM
Subject: Re: [noparse][[/noparse]basicstamps] Re: Power Supply (newbie) question.
> I knew what you meant, thanks. I'm still a little confused about the need
> for a common ground among power supplies that are isolated via a
mechanical
> or solid state relay. Just to be clear, all the TTL stuff will be on a
> single supply.
>
> (sorry for the blank posts)
>
> Rob
>
> I have here a ST35 2v unipolar stepper
>
Original Message
From: pm [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=Tf8_qS9AR335X0UBykeMyGOTk4o54ftceuArv_QWX_36jjj8wzyAQCvatlnd04xB7wKhoWin]pmeloy@s...[/url
Sent: Thursday, July 10, 2003 7:12 PM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] Power Supply (newbie) question.
I'm not clear on some information here
You mentioned a 24vac 600mA solenoid but didn't give any information
about the relay thats resetting your stamp. What are its requirements?
What are you switching it with (transistor, photorelay, ULN2x03?
The stamp pins can only source a small amount of power (an led for
example). If you're going directly to a relay pin then resetting the
stamp is not only inevitable, its a godsend - t should burn the poor
thing out!
If not, what's between the stamp and the relay?
Also, whats the stats on the motor? I have here a ST35 2v unipolar
stepper motor that requires 60mA per winding. Right beside it is an AEG
SO21 5v bipolar stepper that requires 625mA per winding. Even though the
ST35 is over twice the voltage, my 300mA 12v wall wart drives it, my
MCU. 4 leds and a ULN2803 with power to burn. The 5V motor would burn it
out in no time.
In other words, details man, details [noparse]:)[/noparse]
Original Message
From: "Robert Rothe" <rrothe@m...>
To: <basicstamps@yahoogroups.com>
Sent: Thursday, July 10, 2003 3:27 PM
Subject: [noparse][[/noparse]basicstamps] Power Supply (newbie) question.
> I'm working on a BS-1 application to control some motors and
> solenoids. I
think I have a handle on the control portion of the project (ie, relays,
SSRs, etc). My question is 'how do you power all this stuff easily?'
>
> The stamp is currently being run off of a wall-wart power supply
> through a
7805. The motors draw a lot of current at bot 5 and 12 volts.
>
> I also have one solenoid that requires 24v AC 600ma. (which I'm
> assuming I
can probably run on 12 v DC).
>
> So, should I:
>
> a) try and find a wall-wart power supply that can deliver over 1 amp
> at
12V and just run the 12V through the 7085 for the stamp, too?
>
> b) Maybe use an old computer power supply since it can source 5 and 12
volts with higher currents? (I've googled this idea and think I
understand the "no-load" considerations)
>
> c) Use separate sources for each device? (ie, no common ground; load
devices controlled through either relays or SSRs)
>
>
> This problem came to light when I tried to run a 1.3v or 9v motor
> though a
relay controlled by the BS-1. I was trying to pull all the power from
the 7085 (or before the 7805 for the 9v loads) and the stamp kept
reseting when the motor was connected to the Normally Open relay contact
and the relay actived by the stamp. Oddly, it worked OK on the Normally
Closed contact. Lower current loads worked fine on both, so I'm assuming
I was overloading the 7805 or the power supply. The DC power supply was
a 12v 300ma or so radio shack special. I don't know the exact amp
rating on the small hobby motors.
>
>
> Any help and advice would be greatly appreciated. Cost is a serious
consideration. I'm new at this, so please type slow and small :-)
>
> Rob
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject
> and
Body of the message will be ignored.
>
>
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> http://docs.yahoo.com/info/terms/
>
>
To UNSUBSCRIBE, just send mail to:
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with a protecting diode as described in a few of the stamp app
notes. In my tests, the relay is a radio shack SPDT 5V coil which
can drive up to an amp at 120V. (base of transister goes to a stamp
pin with an inline resistor; collector connected to the diode and
the relay; other end of the relay/diode connected to the 7805
regulated output, emitter to ground)
The stamp is powered through the same wall-wart via a 7805 (with caps
in place).
Evenutally, I'll really be driving 12V geared DC motors (ie,
windsheild wiper motors) and air/water solenoid valves. Some of the
solenoids are 120V AC, so basically these are driven directly from a
house line through a mechanical or solid state relay. The DC
solenoids, however, will probably overwhelm most consumer wall-warts.
So, I'd like to continue powering the stamp circuits and the coil
side of the relays with a single, say, 12V supply. What would you
all recommend to drive the DC loads?
--- In basicstamps@yahoogroups.com, pm <pmeloy@s...> wrote:
> I'm not clear on some information here
>
> You mentioned a 24vac 600mA solenoid but didn't give any
information about
> the relay thats resetting your stamp. What are its requirements?
What are
> you switching it with (transistor, photorelay, ULN2x03?
>
> The stamp pins can only source a small amount of power (an led for
example).
> If you're going directly to a relay pin then resetting the stamp is
not only
> inevitable, its a godsend - t should burn the poor thing out!
>
> If not, what's between the stamp and the relay?
>
> Also, whats the stats on the motor? I have here a ST35 2v unipolar
stepper
> motor that requires 60mA per winding. Right beside it is an AEG
SO21 5v
> bipolar stepper that requires 625mA per winding. Even though the
ST35 is
> over twice the voltage, my 300mA 12v wall wart drives it, my MCU. 4
leds and
> a ULN2803 with power to burn. The 5V motor would burn it out in no
time.
>
> In other words, details man, details [noparse]:)[/noparse]
>
>
>
Original Message
> From: "Robert Rothe" <rrothe@m...>
> To: <basicstamps@yahoogroups.com>
> Sent: Thursday, July 10, 2003 3:27 PM
> Subject: [noparse][[/noparse]basicstamps] Power Supply (newbie) question.
>
>
> > I'm working on a BS-1 application to control some motors and
solenoids. I
> think I have a handle on the control portion of the project (ie,
relays,
> SSRs, etc). My question is 'how do you power all this stuff
easily?'
> >
> > The stamp is currently being run off of a wall-wart power supply
through a
> 7805. The motors draw a lot of current at bot 5 and 12 volts.
> >
> > I also have one solenoid that requires 24v AC 600ma. (which I'm
assuming I
> can probably run on 12 v DC).
> >
> > So, should I:
> >
> > a) try and find a wall-wart power supply that can deliver over 1
amp at
> 12V and just run the 12V through the 7085 for the stamp, too?
> >
> > b) Maybe use an old computer power supply since it can source 5
and 12
> volts with higher currents? (I've googled this idea and think I
understand
> the "no-load" considerations)
> >
> > c) Use separate sources for each device? (ie, no common ground;
load
> devices controlled through either relays or SSRs)
> >
> >
> > This problem came to light when I tried to run a 1.3v or 9v motor
though a
> relay controlled by the BS-1. I was trying to pull all the power
from the
> 7085 (or before the 7805 for the 9v loads) and the stamp kept
reseting when
> the motor was connected to the Normally Open relay contact and the
relay
> actived by the stamp. Oddly, it worked OK on the Normally Closed
contact.
> Lower current loads worked fine on both, so I'm assuming I was
overloading
> the 7805 or the power supply. The DC power supply was a 12v 300ma
or so
> radio shack special. I don't know the exact amp rating on the
small hobby
> motors.
> >
> >
> > Any help and advice would be greatly appreciated. Cost is a
serious
> consideration. I'm new at this, so please type slow and small :-)
> >
> > Rob
> >
> >
> > [noparse][[/noparse]Non-text portions of this message have been removed]
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the
Subject and
> Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
One piece of information you keep neglecting to include, what is the
coil-side current requirement of these relays? There will be two current
ratings for a relay, one for the contacts (the motor side) and one for the
coil.
As an example, I have some JE1-DC12V relays here. The contacts are rated for
120VAC @ 5Amps. The coil is 12v and requires 33mA to to hold open. I'm
pretty rusty on DC coil characteristics, but I also believe that the initial
current to switch the contacts is a fair bit higher than that required to
keep them switched. Can't find that mentioned on my datasheet though.
Anyway, no reason why you can't power all the DC stuff from a single wall
wart. Just add up all your power requirements (include ALL the coils,
whether or not you'll be switching them all at the same time) and choose a
wall wart that has at least 25% more supply than you need. I've seen 12VDC
2A bricks kicking around in the local electronics shops. If your current
requirements are higher than you can find, nothing wrong with seperating the
logic power from motor power.
Original Message
From: "rrothe64" <rrothe@m...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, July 11, 2003 11:02 AM
Subject: [noparse][[/noparse]basicstamps] Re: Power Supply (newbie) question.
> Each mechanical relay is driven by the stamp through a transistor
> with a protecting diode as described in a few of the stamp app
> notes. In my tests, the relay is a radio shack SPDT 5V coil which
> can drive up to an amp at 120V. (base of transister goes to a stamp
> pin with an inline resistor; collector connected to the diode and
> the relay; other end of the relay/diode connected to the 7805
> regulated output, emitter to ground)
>
> The stamp is powered through the same wall-wart via a 7805 (with caps
> in place).
>
> Evenutally, I'll really be driving 12V geared DC motors (ie,
> windsheild wiper motors) and air/water solenoid valves. Some of the
> solenoids are 120V AC, so basically these are driven directly from a
> house line through a mechanical or solid state relay. The DC
> solenoids, however, will probably overwhelm most consumer wall-warts.
>
> So, I'd like to continue powering the stamp circuits and the coil
> side of the relays with a single, say, 12V supply. What would you
> all recommend to drive the DC loads?
>
>
As for the coil currents, I can't find the data sheet on the 5v relay, but a
12v model I have (and plan to use) says the "nominal" coil current is 30ma
(with 400 ohm +/- 10% resistance). The drive side of the relay is rated at
10A at 120VAC/24VDC. The relay's leads are a bit skimpy (PC style), but
I'll work through that.
I'll definately look around for a 12V 2amp supply. An old PC power supply
surely fits this bill, too. But it is good to know I can separate them if
needed.
Thanks again for the info!
Rob
PS. Know of any place to scavenge some solid state relays? Are they used
in any consumer quality items? They're pretty pricey new...
Original Message
From: "pm" <pmeloy@s...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, July 11, 2003 12:41 PM
Subject: Re: [noparse][[/noparse]basicstamps] Re: Power Supply (newbie) question.
> Ah ok, you've got the important stuff down pat.
>
> One piece of information you keep neglecting to include, what is the
> coil-side current requirement of these relays? There will be two current
> ratings for a relay, one for the contacts (the motor side) and one for the
> coil.
>
> As an example, I have some JE1-DC12V relays here. The contacts are rated
for
> 120VAC @ 5Amps. The coil is 12v and requires 33mA to to hold open. I'm
> pretty rusty on DC coil characteristics, but I also believe that the
initial
> current to switch the contacts is a fair bit higher than that required to
> keep them switched. Can't find that mentioned on my datasheet though.
>
> Anyway, no reason why you can't power all the DC stuff from a single wall
> wart. Just add up all your power requirements (include ALL the coils,
> whether or not you'll be switching them all at the same time) and choose a
> wall wart that has at least 25% more supply than you need. I've seen 12VDC
> 2A bricks kicking around in the local electronics shops. If your current
> requirements are higher than you can find, nothing wrong with seperating
the
> logic power from motor power.
>
>
>
Original Message
> From: "rrothe64" <rrothe@m...>
> To: <basicstamps@yahoogroups.com>
> Sent: Friday, July 11, 2003 11:02 AM
> Subject: [noparse][[/noparse]basicstamps] Re: Power Supply (newbie) question.
>
>
> > Each mechanical relay is driven by the stamp through a transistor
> > with a protecting diode as described in a few of the stamp app
> > notes. In my tests, the relay is a radio shack SPDT 5V coil which
> > can drive up to an amp at 120V. (base of transister goes to a stamp
> > pin with an inline resistor; collector connected to the diode and
> > the relay; other end of the relay/diode connected to the 7805
> > regulated output, emitter to ground)
> >
> > The stamp is powered through the same wall-wart via a 7805 (with caps
> > in place).
> >
> > Evenutally, I'll really be driving 12V geared DC motors (ie,
> > windsheild wiper motors) and air/water solenoid valves. Some of the
> > solenoids are 120V AC, so basically these are driven directly from a
> > house line through a mechanical or solid state relay. The DC
> > solenoids, however, will probably overwhelm most consumer wall-warts.
> >
> > So, I'd like to continue powering the stamp circuits and the coil
> > side of the relays with a single, say, 12V supply. What would you
> > all recommend to drive the DC loads?
> >
> >
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
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>
>
datasheets. just type the model number and "datasheet". dashes are usually a
killer though, so if its DC5V-SOMETHING , try it with the dash, with a space
instead of a dash, then with no space or dash.
Seaching for the manufacturer helps quite often too [noparse]:)[/noparse]
Original Message
From: "Robert Rothe" <rrothe@m...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, July 11, 2003 6:50 PM
Subject: Re: [noparse][[/noparse]basicstamps] Re: Power Supply (newbie) question.
> This is great info, thanks.
>
> As for the coil currents, I can't find the data sheet on the 5v relay, but
a
> 12v model I have (and plan to use) says the "nominal" coil current is 30ma
> (with 400 ohm +/- 10% resistance). The drive side of the relay is rated
at
> 10A at 120VAC/24VDC. The relay's leads are a bit skimpy (PC style), but
> I'll work through that.
>
> I'll definately look around for a 12V 2amp supply. An old PC power supply
> surely fits this bill, too. But it is good to know I can separate them if
> needed.
>
> Thanks again for the info!
>
> Rob
>
> PS. Know of any place to scavenge some solid state relays? Are they used
> in any consumer quality items? They're pretty pricey new...
>
>
>
>
>
>
>
Original Message
> From: "pm" <pmeloy@s...>
> To: <basicstamps@yahoogroups.com>
> Sent: Friday, July 11, 2003 12:41 PM
> Subject: Re: [noparse][[/noparse]basicstamps] Re: Power Supply (newbie) question.
>
>
> > Ah ok, you've got the important stuff down pat.
> >
> > One piece of information you keep neglecting to include, what is the
> > coil-side current requirement of these relays? There will be two current
> > ratings for a relay, one for the contacts (the motor side) and one for
the
> > coil.
> >
> > As an example, I have some JE1-DC12V relays here. The contacts are rated
> for
> > 120VAC @ 5Amps. The coil is 12v and requires 33mA to to hold open. I'm
> > pretty rusty on DC coil characteristics, but I also believe that the
> initial
> > current to switch the contacts is a fair bit higher than that required
to
> > keep them switched. Can't find that mentioned on my datasheet though.
> >
> > Anyway, no reason why you can't power all the DC stuff from a single
wall
> > wart. Just add up all your power requirements (include ALL the coils,
> > whether or not you'll be switching them all at the same time) and choose
a
> > wall wart that has at least 25% more supply than you need. I've seen
12VDC
> > 2A bricks kicking around in the local electronics shops. If your current
> > requirements are higher than you can find, nothing wrong with seperating
> the
> > logic power from motor power.
> >
> >
> >
Original Message
> > From: "rrothe64" <rrothe@m...>
> > To: <basicstamps@yahoogroups.com>
> > Sent: Friday, July 11, 2003 11:02 AM
> > Subject: [noparse][[/noparse]basicstamps] Re: Power Supply (newbie) question.
> >
> >
> > > Each mechanical relay is driven by the stamp through a transistor
> > > with a protecting diode as described in a few of the stamp app
> > > notes. In my tests, the relay is a radio shack SPDT 5V coil which
> > > can drive up to an amp at 120V. (base of transister goes to a stamp
> > > pin with an inline resistor; collector connected to the diode and
> > > the relay; other end of the relay/diode connected to the 7805
> > > regulated output, emitter to ground)
> > >
> > > The stamp is powered through the same wall-wart via a 7805 (with caps
> > > in place).
> > >
> > > Evenutally, I'll really be driving 12V geared DC motors (ie,
> > > windsheild wiper motors) and air/water solenoid valves. Some of the
> > > solenoids are 120V AC, so basically these are driven directly from a
> > > house line through a mechanical or solid state relay. The DC
> > > solenoids, however, will probably overwhelm most consumer wall-warts.
> > >
> > > So, I'd like to continue powering the stamp circuits and the coil
> > > side of the relays with a single, say, 12V supply. What would you
> > > all recommend to drive the DC loads?
> > >
> > >
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the Subject
and
> Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>