Yuck need power help
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Posts: 46,084
If you are frying LEDs the voltage across the LED must be too great (which
causes too much current through the LED). put a resistor in series with the
led. This resistor will help limit the current through the LED. Many LEDs
work fine while drawing 20 mA. By reducing the current draw in your
circuit, this will help out your voltage regulator not to work so hard.
Original Message
From: Cy Brown <bushman@t...>
To: <basicstamps@yahoogroups.com>
Sent: Sunday, February 04, 2001 12:58 AM
Subject: Re: [noparse][[/noparse]basicstamps] Yuck need power help
> Thanks just the answer I was looking for
> However when I turn mine to 4 volts it works fine
> *shrug*
> Ive been playing around with different circuits to get the feel for things
> before I burn up my stamp like I do all of these LEDs [noparse]:)[/noparse]
>
> Thanks for the answers guys!!
> *runs off to fry more leds*
>
>
>
>
Original Message
> From: <samhell@s...>
> To: <basicstamps@yahoogroups.com>
> Sent: Saturday, February 03, 2001 6:50 PM
> Subject: Re: [noparse][[/noparse]basicstamps] Yuck need power help
>
>
> Cy,
> from what I gather, you really just want your stamp to work with A/C
> power......by BOE came with a "SPECTRE" brand wall wart that outputs 9.0 V
> DC at 300 mA.....this device powers my BOE fine and my carrier board
> version, (both BS2s)......I would suggest getting one of these and trying
> it....you should be ok.
>
>
> Dave
>
>
Original Message
> From: goflo@p... <goflo@p...>
> To: basicstamps@yahoogroups.com <basicstamps@yahoogroups.com>
> Date: Saturday, February 03, 2001 12:29 PM
> Subject: Re: [noparse][[/noparse]basicstamps] Yuck need power help
>
>
> >Cy Brown wrote:
> >>
> >> Im having some serious power problems when I first got my Basic
> >> stamp kit I quickly realized that I had such a horrible level of basic
> >> electronics knowledge that I was doomed. So I got a hold of some
> >> basic electronics refresher books that have helped me greatly.
> >> However, I don't understand one thing. Why is it that power is always
> >> rated in Voltage and seldom is the amp level mentioned?
> >
> >Power is measured in watts, = Volts X Amps
> >
> >> That leads to my current problem (pun intended). I hook up a good
> >> old 9v cell to my board of education and everything is fine except for
> >> the fact that they are somewhat expensive. So I run out and buy a
> >> rechargable 9v the Nickel Metal Hydride type but it seems to puch so
> >> much juice that the stamp wont respond! Im guessing this because I
> >> see the power LED grow dim after a sec or two and that usually means
> >> an overheat.
> >
> >NiMH has high self-discharge rate, meaning the battery goes flat
> >rapidly sitting on the shelf - May need to be charged. Check the
> >voltage with load applied, should be at least 8.4V or so fully
> >charged.
> >
> > I also bought a wall transformer that has a variable
> >> voltage setting on it from 5 to 12 volts but again its rated to puch
> >> 1000milliamps. Im guessing thats too much because the stamp wont
> >> respond when its plugged in either. Can anyone clear this up for me?
> >> At 9V how many amps should I be pushing to make the stamp work?
> >
> >With wall-warts you need to be conscious of polarity - Power-out
> >jacks come wired either way - Adjustable warts often have several
> >jacks, and it's up to you to verify which is what, or else... [noparse]:)[/noparse]
> >Not familiar with the BOE - Perhaps the design provides protection
> >against inadvertent power reversal, but it's a good idea to check
> >power polarity BEFORE you connect it to your circuit.
> >If your BOE still works with the 9V alkaline battery then it's
> >probably OK.
> >
> >You do have a meter, right?
> >
> >Jack
> >
> >
> >
> >
> >
>
>
>
>
>
>
>
>
>
causes too much current through the LED). put a resistor in series with the
led. This resistor will help limit the current through the LED. Many LEDs
work fine while drawing 20 mA. By reducing the current draw in your
circuit, this will help out your voltage regulator not to work so hard.
Original Message
From: Cy Brown <bushman@t...>
To: <basicstamps@yahoogroups.com>
Sent: Sunday, February 04, 2001 12:58 AM
Subject: Re: [noparse][[/noparse]basicstamps] Yuck need power help
> Thanks just the answer I was looking for
> However when I turn mine to 4 volts it works fine
> *shrug*
> Ive been playing around with different circuits to get the feel for things
> before I burn up my stamp like I do all of these LEDs [noparse]:)[/noparse]
>
> Thanks for the answers guys!!
> *runs off to fry more leds*
>
>
>
>
Original Message
> From: <samhell@s...>
> To: <basicstamps@yahoogroups.com>
> Sent: Saturday, February 03, 2001 6:50 PM
> Subject: Re: [noparse][[/noparse]basicstamps] Yuck need power help
>
>
> Cy,
> from what I gather, you really just want your stamp to work with A/C
> power......by BOE came with a "SPECTRE" brand wall wart that outputs 9.0 V
> DC at 300 mA.....this device powers my BOE fine and my carrier board
> version, (both BS2s)......I would suggest getting one of these and trying
> it....you should be ok.
>
>
> Dave
>
>
Original Message
> From: goflo@p... <goflo@p...>
> To: basicstamps@yahoogroups.com <basicstamps@yahoogroups.com>
> Date: Saturday, February 03, 2001 12:29 PM
> Subject: Re: [noparse][[/noparse]basicstamps] Yuck need power help
>
>
> >Cy Brown wrote:
> >>
> >> Im having some serious power problems when I first got my Basic
> >> stamp kit I quickly realized that I had such a horrible level of basic
> >> electronics knowledge that I was doomed. So I got a hold of some
> >> basic electronics refresher books that have helped me greatly.
> >> However, I don't understand one thing. Why is it that power is always
> >> rated in Voltage and seldom is the amp level mentioned?
> >
> >Power is measured in watts, = Volts X Amps
> >
> >> That leads to my current problem (pun intended). I hook up a good
> >> old 9v cell to my board of education and everything is fine except for
> >> the fact that they are somewhat expensive. So I run out and buy a
> >> rechargable 9v the Nickel Metal Hydride type but it seems to puch so
> >> much juice that the stamp wont respond! Im guessing this because I
> >> see the power LED grow dim after a sec or two and that usually means
> >> an overheat.
> >
> >NiMH has high self-discharge rate, meaning the battery goes flat
> >rapidly sitting on the shelf - May need to be charged. Check the
> >voltage with load applied, should be at least 8.4V or so fully
> >charged.
> >
> > I also bought a wall transformer that has a variable
> >> voltage setting on it from 5 to 12 volts but again its rated to puch
> >> 1000milliamps. Im guessing thats too much because the stamp wont
> >> respond when its plugged in either. Can anyone clear this up for me?
> >> At 9V how many amps should I be pushing to make the stamp work?
> >
> >With wall-warts you need to be conscious of polarity - Power-out
> >jacks come wired either way - Adjustable warts often have several
> >jacks, and it's up to you to verify which is what, or else... [noparse]:)[/noparse]
> >Not familiar with the BOE - Perhaps the design provides protection
> >against inadvertent power reversal, but it's a good idea to check
> >power polarity BEFORE you connect it to your circuit.
> >If your BOE still works with the 9V alkaline battery then it's
> >probably OK.
> >
> >You do have a meter, right?
> >
> >Jack
> >
> >
> >
> >
> >
>
>
>
>
>
>
>
>
>
Comments
··· That leads to my current problem (pun intended).· I hook up a good old 9v cell to my board of education and everything is fine except for the fact that they are somewhat expensive.· So I run out and buy a rechargable 9v the Nickel Metal Hydride type but it seems to puch so much juice that the stamp wont respond!· Im guessing this because I see the power LED grow dim after a sec or two and that usually means an overheat.· I also bought a wall transformer that has a variable voltage setting on it from 5 to 12 volts but again its rated to puch 1000milliamps.· Im guessing thats too much because the stamp wont respond when its plugged in either.· Can anyone clear this up for me? At 9V how many amps should I be pushing to make the stamp work?
Cy Brown
I would have a very difficult time explaining the difference between volts and amps.· But EVERYBODY felt clueless about it at one time or another, so don't be discouraged.· It is a concept better learned through experience than somebody explaining it to you, and it is a simple concept at that.· Study up on the section of your electronics book that describes Ohms Law, that is probably the most important thing somebody new to electronics can learn.
One more thing, since you are unfamiliar with current, you should probably get a 7805 5V voltage regulator and power the stamp with that instead of using the on board voltage regulator.· The on board regulator has very low output and can be damaged easily.
--Dan
Original Message
From: Cy Brown
To: basicstamps@yahoogroups.com
Sent: Saturday, February 03, 2001 8:46 AM
Subject: [noparse][[/noparse]basicstamps] Yuck need power help
··· Im having some serious power problems when I first got my Basic stamp kit I quickly realized that I had such a horrible level of basic electronics knowledge that I was doomed.· So I got a hold of some basic electronics refresher books that have helped me greatly.· However, I don't understand one thing.· Why is it that power is always rated in Voltage and seldom is the amp level mentioned?·
··· That leads to my current problem (pun intended).· I hook up a good old 9v cell to my board of education and everything is fine except for the fact that they are somewhat expensive.· So I run out and buy a rechargable 9v the Nickel Metal Hydride type but it seems to puch so much juice that the stamp wont respond!· Im guessing this because I see the power LED grow dim after a sec or two and that usually means an overheat.· I also bought a wall transformer that has a variable voltage setting on it from 5 to 12 volts but again its rated to puch 1000milliamps.· Im guessing thats too much because the stamp wont respond when its plugged in either.· Can anyone clear this up for me? At 9V how many amps should I be pushing to make the stamp work?
Cy Brown
think.
How much horsepower does your car's engine produce? Right now? Good chance
is that right now it produces 0HP because it is in the garage.
This is the same thing with a battery or any other power supply. The voltage
is a measure of potential energy and therefore, a 9V battery is more or less
always 9V. However, the current is a measure of actual energy. So a power
supply rated at 9V 1A does not "push" 1A through anything. It is capable of
handling 1A if you draw 1A from it in the same way that your car is capable
of creating a certain HP if you push the gas pedal down far enough.
That being said, here are some things to think about.
* Many AC powered supplies are not regulated. So a 12V 1A supply won't show
close to 12V without a 1A load. Metering it "open" (nothing connected to it)
might show 18V. Try to draw 1.2A from it and the voltage might drop to 10V.
* Voltage is not power. Current is not power. Voltage and current together
are power (that's why P= EI). Consider that when you shuffle your feet over
carpet you can develop voltages around 100,000V -- but very little current.
Voltage is only a potential amount of power (work). Current is the actual
force that does the work (flow of electrons).
* Batteries are often rated in Amp-Hours. 1AH would indicate a battery that
could deliver 1A for 1 hour (someone correct me if I'm wrong on this). Most
batteries really have a mAH (milliAmp hour) rating. What is the rating of
your NiMH battery?
You might find the article at http://www.al-williams.com/wd5gnr/basiccir.htm
interesting.
The analogy that many people use -- and I hate to use it, but it works -- is
a water tank. Voltage is the level of water in the tank (pressure). In fact
in very old books you can find the term electron pressure. But a tank of
water doesn't do work. Punch a hole in the tank and water pours out
(current). The more water that moves, the more work is done. For the same
size hole, more water pours out if there is more water pressure. The hole is
like a resistor. The bigger the hole (less resistance) the more current
flows and the more work is done. Bigger holes draw more current until you
drain all the water (drain the battery).
Hope that helps!
Al Williams
AWC
* Floating point math for the Stamp, PIC, SX, or any microcontroller:
http://www.al-williams.com/awce/pak1.htm
Original Message
From: Cy Brown [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=oBTcF3EJVQ_0xne6Qjm-KLCHlLuf9bjGD1Jze3DRcB9tlPbvAcEXi0vPysp4e1Xuo0YuYJjY0TpMUcIFyQ]bushman@t...[/url
Sent: Saturday, February 03, 2001 10:47 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Yuck need power help
Im having some serious power problems when I first got my Basic stamp
kit I quickly realized that I had such a horrible level of basic electronics
knowledge that I was doomed. So I got a hold of some basic electronics
refresher books that have helped me greatly. However, I don't understand
one thing. Why is it that power is always rated in Voltage and seldom is
the amp level mentioned?
That leads to my current problem (pun intended). I hook up a good old
9v cell to my board of education and everything is fine except for the fact
that they are somewhat expensive. So I run out and buy a rechargable 9v the
Nickel Metal Hydride type but it seems to puch so much juice that the stamp
wont respond! Im guessing this because I see the power LED grow dim after a
sec or two and that usually means an overheat. I also bought a wall
transformer that has a variable voltage setting on it from 5 to 12 volts but
again its rated to puch 1000milliamps. Im guessing thats too much because
the stamp wont respond when its plugged in either. Can anyone clear this up
for me? At 9V how many amps should I be pushing to make the stamp work?
Cy Brown
>
> Im having some serious power problems when I first got my Basic
> stamp kit I quickly realized that I had such a horrible level of basic
> electronics knowledge that I was doomed. So I got a hold of some
> basic electronics refresher books that have helped me greatly.
> However, I don't understand one thing. Why is it that power is always
> rated in Voltage and seldom is the amp level mentioned?
Power is measured in watts, = Volts X Amps
> That leads to my current problem (pun intended). I hook up a good
> old 9v cell to my board of education and everything is fine except for
> the fact that they are somewhat expensive. So I run out and buy a
> rechargable 9v the Nickel Metal Hydride type but it seems to puch so
> much juice that the stamp wont respond! Im guessing this because I
> see the power LED grow dim after a sec or two and that usually means
> an overheat.
NiMH has high self-discharge rate, meaning the battery goes flat
rapidly sitting on the shelf - May need to be charged. Check the
voltage with load applied, should be at least 8.4V or so fully
charged.
I also bought a wall transformer that has a variable
> voltage setting on it from 5 to 12 volts but again its rated to puch
> 1000milliamps. Im guessing thats too much because the stamp wont
> respond when its plugged in either. Can anyone clear this up for me?
> At 9V how many amps should I be pushing to make the stamp work?
With wall-warts you need to be conscious of polarity - Power-out
jacks come wired either way - Adjustable warts often have several
jacks, and it's up to you to verify which is what, or else... [noparse]:)[/noparse]
Not familiar with the BOE - Perhaps the design provides protection
against inadvertent power reversal, but it's a good idea to check
power polarity BEFORE you connect it to your circuit.
If your BOE still works with the 9V alkaline battery then it's
probably OK.
You do have a meter, right?
Jack
from what I gather, you really just want your stamp to work with A/C
power......by BOE came with a "SPECTRE" brand wall wart that outputs 9.0 V
DC at 300 mA.....this device powers my BOE fine and my carrier board
version, (both BS2s)......I would suggest getting one of these and trying
it....you should be ok.
Dave
Original Message
From: goflo@p... <goflo@p...>
To: basicstamps@yahoogroups.com <basicstamps@yahoogroups.com>
Date: Saturday, February 03, 2001 12:29 PM
Subject: Re: [noparse][[/noparse]basicstamps] Yuck need power help
>Cy Brown wrote:
>>
>> Im having some serious power problems when I first got my Basic
>> stamp kit I quickly realized that I had such a horrible level of basic
>> electronics knowledge that I was doomed. So I got a hold of some
>> basic electronics refresher books that have helped me greatly.
>> However, I don't understand one thing. Why is it that power is always
>> rated in Voltage and seldom is the amp level mentioned?
>
>Power is measured in watts, = Volts X Amps
>
>> That leads to my current problem (pun intended). I hook up a good
>> old 9v cell to my board of education and everything is fine except for
>> the fact that they are somewhat expensive. So I run out and buy a
>> rechargable 9v the Nickel Metal Hydride type but it seems to puch so
>> much juice that the stamp wont respond! Im guessing this because I
>> see the power LED grow dim after a sec or two and that usually means
>> an overheat.
>
>NiMH has high self-discharge rate, meaning the battery goes flat
>rapidly sitting on the shelf - May need to be charged. Check the
>voltage with load applied, should be at least 8.4V or so fully
>charged.
>
> I also bought a wall transformer that has a variable
>> voltage setting on it from 5 to 12 volts but again its rated to puch
>> 1000milliamps. Im guessing thats too much because the stamp wont
>> respond when its plugged in either. Can anyone clear this up for me?
>> At 9V how many amps should I be pushing to make the stamp work?
>
>With wall-warts you need to be conscious of polarity - Power-out
>jacks come wired either way - Adjustable warts often have several
>jacks, and it's up to you to verify which is what, or else... [noparse]:)[/noparse]
>Not familiar with the BOE - Perhaps the design provides protection
>against inadvertent power reversal, but it's a good idea to check
>power polarity BEFORE you connect it to your circuit.
>If your BOE still works with the 9V alkaline battery then it's
>probably OK.
>
>You do have a meter, right?
>
>Jack
>
>
>
>
>
However when I turn mine to 4 volts it works fine
*shrug*
Ive been playing around with different circuits to get the feel for things
before I burn up my stamp like I do all of these LEDs [noparse]:)[/noparse]
Thanks for the answers guys!!
*runs off to fry more leds*
Original Message
From: <samhell@s...>
To: <basicstamps@yahoogroups.com>
Sent: Saturday, February 03, 2001 6:50 PM
Subject: Re: [noparse][[/noparse]basicstamps] Yuck need power help
Cy,
from what I gather, you really just want your stamp to work with A/C
power......by BOE came with a "SPECTRE" brand wall wart that outputs 9.0 V
DC at 300 mA.....this device powers my BOE fine and my carrier board
version, (both BS2s)......I would suggest getting one of these and trying
it....you should be ok.
Dave
Original Message
From: goflo@p... <goflo@p...>
To: basicstamps@yahoogroups.com <basicstamps@yahoogroups.com>
Date: Saturday, February 03, 2001 12:29 PM
Subject: Re: [noparse][[/noparse]basicstamps] Yuck need power help
>Cy Brown wrote:
>>
>> Im having some serious power problems when I first got my Basic
>> stamp kit I quickly realized that I had such a horrible level of basic
>> electronics knowledge that I was doomed. So I got a hold of some
>> basic electronics refresher books that have helped me greatly.
>> However, I don't understand one thing. Why is it that power is always
>> rated in Voltage and seldom is the amp level mentioned?
>
>Power is measured in watts, = Volts X Amps
>
>> That leads to my current problem (pun intended). I hook up a good
>> old 9v cell to my board of education and everything is fine except for
>> the fact that they are somewhat expensive. So I run out and buy a
>> rechargable 9v the Nickel Metal Hydride type but it seems to puch so
>> much juice that the stamp wont respond! Im guessing this because I
>> see the power LED grow dim after a sec or two and that usually means
>> an overheat.
>
>NiMH has high self-discharge rate, meaning the battery goes flat
>rapidly sitting on the shelf - May need to be charged. Check the
>voltage with load applied, should be at least 8.4V or so fully
>charged.
>
> I also bought a wall transformer that has a variable
>> voltage setting on it from 5 to 12 volts but again its rated to puch
>> 1000milliamps. Im guessing thats too much because the stamp wont
>> respond when its plugged in either. Can anyone clear this up for me?
>> At 9V how many amps should I be pushing to make the stamp work?
>
>With wall-warts you need to be conscious of polarity - Power-out
>jacks come wired either way - Adjustable warts often have several
>jacks, and it's up to you to verify which is what, or else... [noparse]:)[/noparse]
>Not familiar with the BOE - Perhaps the design provides protection
>against inadvertent power reversal, but it's a good idea to check
>power polarity BEFORE you connect it to your circuit.
>If your BOE still works with the 9V alkaline battery then it's
>probably OK.
>
>You do have a meter, right?
>
>Jack
>
>
>
>
>
To: <basicstamps@yahoogroups.com>
Date: Sat, 3 Feb 2001 23:58:32 -0600
>Thanks just the answer I was looking for
>However when I turn mine to 4 volts it works fine
>*shrug*
That's because the wallwart is unregulated. If you were to pull the rated amps
from it, you'd find that the voltage output would be much nearer to that
marked on the selector switch. You're pulling much less, so the voltage goes
up.
The moral is, start the wallwart with the switch set at a lower voltage than
you think you need, measure it with the load switched on, and only increase it
if the voltage is lower than the circuit needs. Better still, buy a regulated
supply.
--
Regards,
Derryck Croker