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PostPosted: 15.12.2007 20:10 
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Regular Modder
Regular Modder

Joined: 26.05.2007 10:06
Posts: 128
Location: Texas
This is a VERY IN DEPTH Problem I am having trying to UNDERSTAND the reasonings behind why this will or will not work. If you do not have time to explain this I DO 100% understand, however, if you DO have the time, could you PLEASE explain it in as much DETAIL as you can.

I know that there are many people here who "GET" most of what everyone else is talking about, and they help them. I TOO would like to learn so I can do this as well.



I have posted something similar to part of this before but I am trying to make sure that I UNDERSTAND what was said.

The basics -

- I have about 15 motors that use a 1.5v battery each
- I have several transformers with ratings from 4.0v to 12v.

When I test the transformers (with no load) some have an ACTUAL rating of 18v (I do not REALLY understand this because written on the transformer it CLEARLY states 12v (700mA)

I have been told in other posts that EVEN THOUGH it has written on it 12v it can be MUCH HIGHER (18v in this case) till a load is put on it, and then it will drop down to the rating (12v in this case) that is written on it.

*** IS that true.
-




*** Do I need to worry about frying a "whatever" that is rated at 12v
-






Now for a part two. The MilaAmps. For the motors mentioned at the beginning of this post. There is NOTHING written on the motors. I pulled them out of small Christmas Tree spinners.

*** How do I determine the mA (or does it even matter)
-




*** How do I determine what the mA "draw"(???) is on an item
-




*** Does it matter what the mA is on anything other than an LED, if so WHY?
-




*** If I soldered a positive and a negative wire to the + and - sides of the motors could I use a 12 Vdc (700mA) transformer to run 8 of these motors WIRED IN SERIES. (My thinking is 8 motors at 1.5 each is 1.5 x 8 = 12V so all the current would be utilized)


Now for the same situation as above, a 12Vdc transformer (700mA), 8 motors at 1.5 each, if I were to try to connect them IN PARALLEL with a RESISTOR to drop the current down to about 1.5vdc -

*** would this work
-



*** What is the reason I could not connect 500 motors using this setup.
-





*** Where does the mA come into play (what do they matter)
-





*** IF the mA does matter, and I NEED to know how much each motor takes, can I add up to total of the mA and use that to determine how many motors I can connect up to this power supply.
-






As I said above this is a VERY IN DEPTH Problem I am having trying to UNDERSTAND the reasonings behind why it will and will not work.


Thank You all (even if you just read this)


Dan

BTW - If you are able to reply to this within the message itself, I did leave space under each one for an answer, with the hope that I did not write this in a to confusing manner.


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PostPosted: 15.12.2007 20:58 
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Ultra Modder
Ultra Modder
User avatar

Joined: 09.06.2002 14:10
Posts: 2924
Location: Helsinki, Finland
DanTheMan wrote:
This is a VERY IN DEPTH Problem I am having trying to UNDERSTAND the reasonings behind why this will or will not work. If you do not have time to explain this I DO 100% understand, however, if you DO have the time, could you PLEASE explain it in as much DETAIL as you can.

I know that there are many people here who "GET" most of what everyone else is talking about, and they help them. I TOO would like to learn so I can do this as well.



I have posted something similar to part of this before but I am trying to make sure that I UNDERSTAND what was said.

The basics -

- I have about 15 motors that use a 1.5v battery each
- I have several transformers with ratings from 4.0v to 12v.

When I test the transformers (with no load) some have an ACTUAL rating of 18v (I do not REALLY understand this because written on the transformer it CLEARLY states 12v (700mA)

I have been told in other posts that EVEN THOUGH it has written on it 12v it can be MUCH HIGHER (18v in this case) till a load is put on it, and then it will drop down to the rating (12v in this case) that is written on it.

*** IS that true.
-

Yes that's true.


DanTheMan wrote:
*** Do I need to worry about frying a "whatever" that is rated at 12v
-


Yes and no. Generally - yes.


DanTheMan wrote:

Now for a part two. The MilaAmps. For the motors mentioned at the beginning of this post. There is NOTHING written on the motors. I pulled them out of small Christmas Tree spinners.

*** How do I determine the mA (or does it even matter)
-

Put a multimeter on series with one of your motors when powered. Multimeter has to be on current measuring mode of course. Now you can read the idle rating for that motor. Then if you give some mechanical resistanse for the motor you get current for loaded motor and if you stop the motor you get the maximum current.

DanTheMan wrote:
*** How do I determine what the mA "draw"(???) is on an item
-


*** Does it matter what the mA is on anything other than an LED, if so WHY?
-

Generally no. Because leds are diodes and diodes have constant voltage over anode and cathode (if you measure voltage over the led and change the output voltage of the voltage source it doesn't make any change to voltage over the led. Usually components have "constant" resistance over them which defines voltage and current.


DanTheMan wrote:

*** If I soldered a positive and a negative wire to the + and - sides of the motors could I use a 12 Vdc (700mA) transformer to run 8 of these motors WIRED IN SERIES. (My thinking is 8 motors at 1.5 each is 1.5 x 8 = 12V so all the current would be utilized)

I don't recomend it. Because resistace of the motors is not excatly same. Especially on loaded motors.

DanTheMan wrote:
Now for the same situation as above, a 12Vdc transformer (700mA), 8 motors at 1.5 each, if I were to try to connect them IN PARALLEL with a RESISTOR to drop the current down to about 1.5vdc -

*** would this work
-

Yes and no. Not like you think. Because the circuit divides voltage over the resistor and your motors. If you load one or more of those motors it will change the parallel resistance of the motors. So you get different divide ratio and different voltage over the motors.

DanTheMan wrote:
*** What is the reason I could not connect 500 motors using this setup.
-

Same as above.


DanTheMan wrote:
*** Where does the mA come into play (what do they matter)
-

Current rating doesn't matter ...if you have cables with infinite wire diameter and voltage source with zero series resistance :) You got it? Current (and voltage) ratings just helps you to choose right wires and power supply.


DanTheMan wrote:

*** IF the mA does matter, and I NEED to know how much each motor takes, can I add up to total of the mA and use that to determine how many motors I can connect up to this power supply.
-

Exactly.



DanTheMan wrote:

As I said above this is a VERY IN DEPTH Problem I am having trying to UNDERSTAND the reasonings behind why it will and will not work.


Thank You all (even if you just read this)


Dan

BTW - If you are able to reply to this within the message itself, I did leave space under each one for an answer, with the hope that I did not write this in a to confusing manner.


I recomend you to buy some book about basics of electricity. http://www.smarthomeusa.com/Shop/Books/Item/BBEY/
and maybe something about circuit analysis
http://www.amazon.com/Schaums-Outline-B ... 0070478244

_________________
Lensflare
http://lensflare.fi/
http://www.flickr.com/photos/ollivanhoja/
http://hbp.deviantart.com/


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PostPosted: 15.12.2007 20:59 
Offline
Super Modder
Super Modder

Joined: 15.07.2005 20:33
Posts: 1314
Location: Tampere, Finland.
WHOOOOOPS Olli already answered while I was writing this. Damnit.

DanTheMan wrote:

The basics -

- I have about 15 motors that use a 1.5v battery each
- I have several transformers with ratings from 4.0v to 12v.

When I test the transformers (with no load) some have an ACTUAL rating of 18v (I do not REALLY understand this because written on the transformer it CLEARLY states 12v (700mA)

I have been told in other posts that EVEN THOUGH it has written on it 12v it can be MUCH HIGHER (18v in this case) till a load is put on it, and then it will drop down to the rating (12v in this case) that is written on it.

*** IS that true.

- If the power supply isn't regulated, the output voltage is over the specified. That kind of power supplies only contain a transformer and a diode bridge and a capacitor that turn the AC into DC.



DanTheMan wrote:
*** Do I need to worry about frying a "whatever" that is rated at 12v

- It depends on the thing you want to power. For example normal light bulbs and motors aren't too shy about the voltage, but most digital electronics get fried by too high voltage. It would always be better to use regulated power supplies, because they output exactly the voltage that's said on the cover.





DanTheMan wrote:
Now for a part two. The MilaAmps. For the motors mentioned at the beginning of this post. There is NOTHING written on the motors. I pulled them out of small Christmas Tree spinners.

*** How do I determine the mA (or does it even matter)

- You can determine the mA simply by measuring it with a multimeter.

Code:
+ --------(Amp meter)-----
                          |
                      (motor)
                          |
- -------------------------


For this it would be good to either use a regulated PSU or to have another multimeter measuring the voltage over the motor. You can also measure the resistance of the motor and then calculate the current from U = R/I (I = U/R). The resistance of motors changes according to the load, so the value isn't too significant anyways.



DanTheMan wrote:
*** How do I determine what the mA "draw"(???) is on an item

-I didn't get this one



DanTheMan wrote:
*** Does it matter what the mA is on anything other than an LED, if so WHY?

- It "matters", but doesn't make too much of a difference. LEDs are basically diodes, and have theoretically zero resistance. Because of this they take more current than it's good for them and eventually burn without the resistor. Motors have resistance of their own, and if their maximum operating voltage isn't exceeded (or they get stalled when the resistance drops) they don't burn.



DanTheMan wrote:
*** If I soldered a positive and a negative wire to the + and - sides of the motors could I use a 12 Vdc (700mA) transformer to run 8 of these motors WIRED IN SERIES. (My thinking is 8 motors at 1.5 each is 1.5 x 8 = 12V so all the current would be utilized)

- Yes.

DanTheMan wrote:
Now for the same situation as above, a 12Vdc transformer (700mA), 8 motors at 1.5 each, if I were to try to connect them IN PARALLEL with a RESISTOR to drop the current down to about 1.5vdc -

*** would this work

- You can't drop the voltage simply by resistor, because the resistance of the motors changes according to the load. When the resistance of the load changes, the voltage gets divided differently between the resistor and the motor. Resistors don't work as voltage droppers for anything with varying resistance.


DanTheMan wrote:
*** What is the reason I could not connect 500 motors using this setup.

- Read above.




DanTheMan wrote:
*** Where does the mA come into play (what do they matter)
Quote:
- If the motors are connected in series (8 * 1,5 V) then they take as much current from the power supply as a single motor does. If you measured it earlier, you know the amount by now. And the current doesn't matter as long as it's under 700 mA and the transformer doesn't get over-loaded.

If the current is low (10 mA or so) then the transformer may still put out more than 12 volts. It's hard to say how this works with your transformers, but this phenomena should be there at some level




DanTheMan wrote:
*** IF the mA does matter, and I NEED to know how much each motor takes, can I add up to total of the mA and use that to determine how many motors I can connect up to this power supply.

- Yes. But you just have to keep in mind that the current changes according to the load. Motors are a bad example for current/voltage/resistance things because of that factor :/



I hope this helped. If you don't already have a multimeter, I STRONGLY suggest you to get atleast one. It helps so much always when you work with electric stuff.

_________________
A mountain of hardware and gazillion 3dmarks.


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PostPosted: 16.12.2007 10:34 
Offline
Regular Modder
Regular Modder

Joined: 26.05.2007 10:06
Posts: 128
Location: Texas
FIRST and FOREMOST THANK YOU for trying to help me understand. I HONESTLY do appreciate You for giving of yourself to better others. You and Jipa (and several others as well) REALLY do make an effort to help.


Olli wrote:
DanTheMan wrote:
This is a VERY IN DEPTH Problem I am having trying to UNDERSTAND the reasonings behind why this will or will not work. If you do not have time to explain this I DO 100% understand, however, if you DO have the time, could you PLEASE explain it in as much DETAIL as you can.

I know that there are many people here who "GET" most of what everyone else is talking about, and they help them. I TOO would like to learn so I can do this as well.



I have posted something similar to part of this before but I am trying to make sure that I UNDERSTAND what was said.

The basics -

- I have about 15 motors that use a 1.5v battery each
- I have several transformers with ratings from 4.0v to 12v.

When I test the transformers (with no load) some have an ACTUAL rating of 18v (I do not REALLY understand this because written on the transformer it CLEARLY states 12v (700mA)

I have been told in other posts that EVEN THOUGH it has written on it 12v it can be MUCH HIGHER (18v in this case) till a load is put on it, and then it will drop down to the rating (12v in this case) that is written on it.

*** IS that true.
-

Yes that's true.


DanTheMan wrote:
*** Do I need to worry about frying a "whatever" that is rated at 12v
-


Yes and no. Generally - yes.


DanTheMan wrote:

Now for a part two. The MilaAmps. For the motors mentioned at the beginning of this post. There is NOTHING written on the motors. I pulled them out of small Christmas Tree spinners.

*** How do I determine the mA (or does it even matter)
-

Put a multimeter on series with one of your motors when powered. Multimeter has to be on current measuring mode of course. Now you can read the idle rating for that motor. Then if you give some mechanical resistanse for the motor you get current for loaded motor and if you stop the motor you get the maximum current.


When you say "on series" can you tell me EXACTLY what you mean. I understand that it is with just ONE motor in this case as I read it above, but I am just wanting to MAKE SURE, I know 100% what you mean.





DanTheMan wrote:
*** How do I determine what the mA "draw"(???) is on an item
-


*** Does it matter what the mA is on anything other than an LED, if so WHY?
-

Generally no. Because leds are diodes and diodes have constant voltage over anode and cathode (if you measure voltage over the led and change the output voltage of the voltage source it doesn't make any change to voltage over the led. Usually components have "constant" resistance over them which defines voltage and current.


DanTheMan wrote:

*** If I soldered a positive and a negative wire to the + and - sides of the motors could I use a 12 Vdc (700mA) transformer to run 8 of these motors WIRED IN SERIES. (My thinking is 8 motors at 1.5 each is 1.5 x 8 = 12V so all the current would be utilized)

I don't recomend it. Because resistace of the motors is not excatly same. Especially on loaded motors.

So what you are saying is that even though the motors are made by the same people, at the same company and same time and so on, that there may be a slight (or even a significant) difference on what each motor may pull / draw from the power source and that in turn will effect how fast / slow the motor will turn.



DanTheMan wrote:
Now for the same situation as above, a 12Vdc transformer (700mA), 8 motors at 1.5 each, if I were to try to connect them IN PARALLEL with a RESISTOR to drop the current down to about 1.5vdc -

*** would this work
-

Yes and no. Not like you think. Because the circuit divides voltage over the resistor and your motors. If you load one or more of those motors it will change the parallel resistance of the motors. So you get different divide ratio and different voltage over the motors.


OK, I think I MIGHT really kinda (Grin) get this. So lets say IF ALL MOTORS are DIFFERENT, and I put a 1.5 volt power supply on each one, one at a time to test them, and find out that I get a very slow
1 revolutions a minute on some
2 revolutions a minuet on others,
and even still 3 revolutions a minuet on others,

I can connect them to a 12vdc power source that has a FINIAL OUTPUT of 1.3 - 1.5vdc and they all will turn at a different rate. Some slower some a bit faster (relatively speaking) and some almost don't turn at all. Is that what you are saying "kinda"

And I was shooting for a lower output that what the motors are rated for because IF (OK WHEN, Grin) I make a mistake, I really don't want to fry them.


DanTheMan wrote:
*** What is the reason I could not connect 500 motors using this setup.
-

Same as above.


DanTheMan wrote:
*** Where does the mA come into play (what do they matter)
-

Current rating doesn't matter ...if you have cables with infinite wire diameter and voltage source with zero series resistance :) You got it? Current (and voltage) ratings just helps you to choose right wires and power supply.


And here what you are kinda saying is the Current (and voltage) are " guidelines " to make sure I dont use a piece of wire as thin as a pencil lead to run to FROM my local power company to the "mains" in my home . Is that kinda what it is.


DanTheMan wrote:

*** IF the mA does matter, and I NEED to know how much each motor takes, can I add up to total of the mA and use that to determine how many motors I can connect up to this power supply.
-

Exactly.



DanTheMan wrote:

As I said above this is a VERY IN DEPTH Problem I am having trying to UNDERSTAND the reasonings behind why it will and will not work.


Thank You all (even if you just read this)


Dan

BTW - If you are able to reply to this within the message itself, I did leave space under each one for an answer, with the hope that I did not write this in a to confusing manner.


I recomend you to buy some book about basics of electricity. http://www.smarthomeusa.com/Shop/Books/Item/BBEY/
and maybe something about circuit analysis
http://www.amazon.com/Schaums-Outline-B ... 0070478244


Thanks for even providing the links to the books. I have told my Wife ALREADY that I have a few "requests" for Christmas if She can see her way to do it, but we both know (or ALL OF US know) that I will have to beg for them sooner or later. Grin...

I do have a couple of books that I got from Radio Shack, and while I'm told they are very good, I just can not grasp the information in them like I can by asking HERE, and people responding with examples I understand. I know it makes me sound VERY DENSE, but actually talking to people who are DOING what I am trying to do, is so much better for my understanding. I like it when people like you give examples like you did here, and then followed through with the REASONING behind it.

Thank You Again,


Dan



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PostPosted: 16.12.2007 13:26 
Offline
Regular Modder
Regular Modder

Joined: 26.05.2007 10:06
Posts: 128
Location: Texas
Jipa wrote:
WHOOOOOPS Olli already answered while I was writing this. Damnit.

That is more than fine by me, I would LOVE TO GET 50 answers just to see how the little things in what people know differ. Ya never know, someone else could also learn something new or a different way of doing the same thing.

And along the same lines as I told Olli, THANK YOU for sharing what you know. It is a good thing what you do.


DanTheMan wrote:

The basics -

- I have about 15 motors that use a 1.5v battery each
- I have several transformers with ratings from 4.0v to 12v.

When I test the transformers (with no load) some have an ACTUAL rating of 18v (I do not REALLY understand this because written on the transformer it CLEARLY states 12v (700mA)

I have been told in other posts that EVEN THOUGH it has written on it 12v it can be MUCH HIGHER (18v in this case) till a load is put on it, and then it will drop down to the rating (12v in this case) that is written on it.

*** IS that true.

- If the power supply isn't regulated, the output voltage is over the specified. That kind of power supplies only contain a transformer and a diode bridge and a capacitor that turn the AC into DC.

Other than using a multimeter is there a way to find out just by looking at a transformer (power supply) if it is regulated or not.

And if a power supply IS regulated, does that mean with the list you wrote above, it ALSO contains a regulator. (Just guessing, I have no idea if there even is such a thing as a regulator for things of this nature.)




DanTheMan wrote:
*** Do I need to worry about frying a "whatever" that is rated at 12v

- It depends on the thing you want to power. For example normal light bulbs and motors aren't too shy about the voltage, but most digital electronics get fried by too high voltage. It would always be better to use regulated power supplies, because they output exactly the voltage that's said on the cover.

When you say that normal light bulbs and motors aren't too shy about the voltage, do you mean they can / WILL take more voltage than they need but still have a smaller chance of destroying themselves than lets say an LED.

I guess what I am trying to say is that how I read the above is that a regular light bulb or motor can "handle" (or take) more voltage than it is rated for and be less likely to blow or burn out.





DanTheMan wrote:
Now for a part two. The MilaAmps. For the motors mentioned at the beginning of this post. There is NOTHING written on the motors. I pulled them out of small Christmas Tree spinners.

*** How do I determine the mA (or does it even matter)

- You can determine the mA simply by measuring it with a multimeter.

Code:
+ --------(Amp meter)-----
                          |
                      (motor)
                          |
- -------------------------



From the example above, what I "get" of it if anything (I'm not to smart with stuff like that) is I use the positive probe of a multimeter and place it........... OK wait, I went back and looked at the original post from you and I am now thinking that an amp meter IS NOT a multimeter.

Is this correct, or can you use a Multi Meter AS an AMP meter? And if it is correct and you can use a multi meter as an amp meter WHAT do i look for on the MM in order to set it to an AMP meter.

I will post some links for some images so you can see the MM I use. I have two of them along with some other stuff that I STARTED to buy the VERY FIRST TIME I found the Resistor Calculator here on Your website. Now I KNOW I do nto have the toys that many people here do, but I save and try to buy an item or two as needed / wanted once or twice a month. (components or tools)


For this it would be good to either use a regulated PSU or to have another multimeter measuring the voltage over the motor. You can also measure the resistance of the motor and then calculate the current from U = R/I (I = U/R). The resistance of motors changes according to the load, so the value isn't too significant anyways.


With the load of these motors I am using, they are so small and are / were used for Ornaments on trees. These ornaments normally weighed LESS THAN an ounce or TWO at most, and they were hung upside down like a Disco Ball. They spin SUPER SLOW, where like in my post, they MIGHT MAKE 1 or 2 Revolutions per minuet. So I THINK (lookout, Grin) that the only "force" is a force of gravity pulling down on then, and the load as you said above isn't to significant. BUT, I still wanted to know for future use.


DanTheMan wrote:
*** How do I determine what the mA "draw"(???) is on an item

-I didn't get this one



DanTheMan wrote:
*** Does it matter what the mA is on anything other than an LED, if so WHY?

- It "matters", but doesn't make too much of a difference. LEDs are basically diodes, and have theoretically zero resistance. Because of this they take more current than it's good for them and eventually burn without the resistor. Motors have resistance of their own, and if their maximum operating voltage isn't exceeded (or they get stalled when the resistance drops) they don't burn.

OK, THAT answered a couple of questions. With what you said AND HOW YOU SAID IT "Because of this they take more current than it's good for them and eventually burn without the resistor" it makes sense to me.



DanTheMan wrote:
*** If I soldered a positive and a negative wire to the + and - sides of the motors could I use a 12 Vdc (700mA) transformer to run 8 of these motors WIRED IN SERIES. (My thinking is 8 motors at 1.5 each is 1.5 x 8 = 12V so all the current would be utilized)

- Yes.


With your answer of YES, if I were to take one of the motors OUT of the Series above, that would mean (basically) that the other 7 motors would be dividing up the 1.5v that the now missing motor would have used. And would NOW be turning a bit faster than they were when there were 8 motors.

If so, YOU SO KICKS ASS. (Me Understanding ROCKS) If not it's kinda OK too, because I am use-ta not being right. Grin


DanTheMan wrote:
Now for the same situation as above, a 12Vdc transformer (700mA), 8 motors at 1.5 each, if I were to try to connect them IN PARALLEL with a RESISTOR to drop the current down to about 1.5vdc -

*** would this work

- You can't drop the voltage simply by resistor, because the resistance of the motors changes according to the load. When the resistance of the load changes, the voltage gets divided differently between the resistor and the motor. Resistors don't work as voltage droppers for anything with varying resistance.

I think I NOW understand what the resistance part is. Its like if a motor in a winch had to PULL an 18 wheeler Truck out of a ditch compared to the same winch having to PULL a two man row boat across a small pond.

The resistance of the truck would be SOOOOOO much more....

Right ??? (PLEASE SAY YES, Even if it's no...) Grin....






DanTheMan wrote:
*** What is the reason I could not connect 500 motors using this setup.

- Read above.




DanTheMan wrote:
*** Where does the mA come into play (what do they matter)
Quote:
- If the motors are connected in series (8 * 1,5 V) then they take as much current from the power supply as a single motor does. If you measured it earlier, you know the amount by now. And the current doesn't matter as long as it's under 700 mA and the transformer doesn't get over-loaded.

If the current is low (10 mA or so) then the transformer may still put out more than 12 volts. It's hard to say how this works with your transformers, but this phenomena should be there at some level

Ok, I am gonna play with this a bit...


DanTheMan wrote:
*** IF the mA does matter, and I NEED to know how much each motor takes, can I add up to total of the mA and use that to determine how many motors I can connect up to this power supply.

- Yes. But you just have to keep in mind that the current changes according to the load. Motors are a bad example for current/voltage/resistance things because of that factor :/

Jipa, I DO think I have got a better grasp on this now. With what You and Olli have said, I think I might actually KNOW SOMETHING...


I hope this helped. If you don't already have a multimeter, I STRONGLY suggest you to get atleast one. It helps so much always when you work with electric stuff.



This is one of the tackle boxes that I have been using to put stuff when I have been able to get it. I have two Multimeters, (Made by Sperry)

http://www.awsperry.com/sperry/catalog?item=dm-210a
http://www.awsperry.com/sperry/catalog?item=dm-300 (The 350a)

but from what I have read with the user guides about the only difference is that one has a continuity checker and the other one does not. They were on sale and I did not know enough about them to really know what I was getting. The other one on top is just a battery checker from a while ago. The box at the bottom of the image has small things I have been playing with (again after reading about stuff here) The motor in the film container IS NOT the motors that I am talking about above.

Image


In this other tackle box is just a few other things that I have "needed". Instead of a heat gun I found an Embossing tool at a hobby shop for $7.99 so of course I thought is was a good deal. (I DID look for ANYTHING other than pink, but no luck. Grin)
And the Helping Hands I kinda enhanced because I am somewhat all thumbs, and the more help the better.

Image

I took out some of the containers that actually has stuff in them, an here they are. Top one on the left is LED's. 3mm and 5mm (I really can't afford the bigger ones but all in all I am still learning, so for now that is OK. Resistors are in the one on the right. It is a 500 pack from Radio Shack that I have been playing with to understand more. And of course the bottom one is the soldering stuff. I have not gotten (or made) a soldering station like You and a few others have as of yet. Just give me time and I will get to it.

Image


Anyway, I will be back (OF COURSE) and I will eventually post the Xbox 360 cooler I made (BECAUSE OF THIS SITE).

I don't really want to post it now, because there are some TOUGH CRITICS, and I want to do better before i get beat down. Grin...


Dan


BTW - I did preview this post and on my screen (1024x768) the text is all the way across the screen. So much so that I have to scroll to read everything. I am not sure what I done or how to fix it, but if you can, Please do so or tell me how and I will.


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PostPosted: 16.12.2007 15:32 
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I don't want to quote your messaga again, as it would get way too long, but here's some more answers:

I sent you a PM that shows how to use multimeter to measure the voltage and the current. And when I said amp meter, I ment multi meter on the current range (you need to connect it accordingly).

- Usually power supplies aren't regulated when it doesn't say anything on them. So you're better off always measuring the voltage they give out before starting to use them for anything.

- Yes, regulated power supplies contain a regulator besides the other components. (regulation can also be made using zener diodes and some other methods, but that's another topic)

- When one of the eight motors connected to 12 volts is removed, the rest get a bit higher voltage and run a bit faster.

- And I ment exactly that with light bulbs and motors. They shine brighter/run faster at higher voltage, but don't get instantly destroyed. Long-time overvoltage causes the lifespan to shorten, but unlike leds and such, they don't instantly burn. They also work at voltages under the specified, when the lifespan gets longer, but the lamp doesn't shine as brightly.

- On the winch-example; the winch doesn't have to do as much work with the rowboat, so it doesn't require as much power either.

About the multimeters; The 350A seems very similar to those that I use. The 210A is more simplified and it seems like you can't measure currents with it. It's good that you have two of those! Now you can repeat the test shown on the video by using the 210A to measure voltage (connect parallel with the motor) and the 350A to measure the current (connect in series, remember to use the right holes for the cables)

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PostPosted: 17.12.2007 00:26 
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DanTheMan wrote:

Now for a part two. The MilaAmps. For the motors mentioned at the beginning of this post. There is NOTHING written on the motors. I pulled them out of small Christmas Tree spinners.

*** How do I determine the mA (or does it even matter)
-

Put a multimeter on series with one of your motors when powered. Multimeter has to be on current measuring mode of course. Now you can read the idle rating for that motor. Then if you give some mechanical resistanse for the motor you get current for loaded motor and if you stop the motor you get the maximum current.

DanTheMan wrote:

When you say "on series" can you tell me EXACTLY what you mean. I understand that it is with just ONE motor in this case as I read it above, but I am just wanting to MAKE SURE, I know 100% what you mean.


+ ---(M)---(amp meter)--- -

+ ---[controlled PSU]----- -

DanTheMan wrote:

*** If I soldered a positive and a negative wire to the + and - sides of the motors could I use a 12 Vdc (700mA) transformer to run 8 of these motors WIRED IN SERIES. (My thinking is 8 motors at 1.5 each is 1.5 x 8 = 12V so all the current would be utilized)

I don't recomend it. Because resistace of the motors is not excatly same. Especially on loaded motors.


DanTheMan wrote:
So what you are saying is that even though the motors are made by the same people, at the same company and same time and so on, that there may be a slight (or even a significant) difference on what each motor may pull / draw from the power source and that in turn will effect how fast / slow the motor will turn.

Both. There is mechanical differences on motors and there is also difference on mechanical load. For example if you press the shaft with your fingers. It will decrease resistance of the motor and it takes more current then.


DanTheMan wrote:

DanTheMan wrote:

DanTheMan wrote:
Now for the same situation as above, a 12Vdc transformer (700mA), 8 motors at 1.5 each, if I were to try to connect them IN PARALLEL with a RESISTOR to drop the current down to about 1.5vdc -

*** would this work
-

Yes and no. Not like you think. Because the circuit divides voltage over the resistor and your motors. If you load one or more of those motors it will change the parallel resistance of the motors. So you get different divide ratio and different voltage over the motors.


DanTheMan wrote:
OK, I think I MIGHT really kinda (Grin) get this. So lets say IF ALL MOTORS are DIFFERENT, and I put a 1.5 volt power supply on each one, one at a time to test them, and find out that I get a very slow
1 revolutions a minute on some
2 revolutions a minuet on others,
and even still 3 revolutions a minuet on others,

I can connect them to a 12vdc power source that has a FINIAL OUTPUT of 1.3 - 1.5vdc and they all will turn at a different rate. Some slower some a bit faster (relatively speaking) and some almost don't turn at all. Is that what you are saying "kinda"

And I was shooting for a lower output that what the motors are rated for because IF (OK WHEN, Grin) I make a mistake, I really don't want to fry them.


They should revolve at the same speed, but in practice there will be some difference. You could adjust all motors for the same rpm rate by controlling voltage of each motor separately.

DanTheMan wrote:
*** Where does the mA come into play (what do they matter)
-

Current rating doesn't matter ...if you have cables with infinite wire diameter and voltage source with zero series resistance :) You got it? Current (and voltage) ratings just helps you to choose right wires and power supply.


DanTheMan wrote:

And here what you are kinda saying is the Current (and voltage) are " guidelines " to make sure I dont use a piece of wire as thin as a pencil lead to run to FROM my local power company to the "mains" in my home . Is that kinda what it is.


Yes. Voltage tells the diameter of the dielectric material around the conductor and current tells the diameter of the conductor.

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PostPosted: 20.09.2009 12:02 
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Regular Modder
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Joined: 26.05.2007 10:06
Posts: 128
Location: Texas
W O W ... So here it is almost two years gone by sense I posted this, and now that I am back online from home I was searching for things to do with motors and this post came up. Have you ever had one of those " NOW I GET IT " type moments...

Well this did it for me. I have not been able to be online lately and I MISS METKU SOMETHING FIERCE !

When you go through tough times and have to cut out your Net Access, MAN it can REALLY STINK to say the least... Now I have my priorities in line... Next time (hopefully there wont be one) But if there is, next time, I will KEEP my net access, and only eat once a day... Grin...


Hope everyone is well...


Dan


- now to figure out what to do with a few printer motors.


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PostPosted: 20.09.2009 13:59 
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Site Admin
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Joined: 24.01.2002 10:09
Posts: 4683
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Hehe, welcome back. :) We do not get that many forum posts these days so it is great to see you back. We could use couple of more active posters like you. :)


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PostPosted: 26.12.2009 00:36 
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Regular Modder
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Joined: 26.05.2007 10:06
Posts: 128
Location: Texas
OK, That makes me upset. I am not going to have to go back and find the images of what this post was about. I don't want to confuse anyone anymore than I already do !


Grin...


Dan


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