Beginner needs help

Discussion in 'General Electronics Discussion' started by cat50, Aug 11, 2009.

1. cat50

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0
Aug 11, 2009
Hello all I am new here and new to electronics. I have done basic and I mean very basic wiring. Battery to a mini lamp and toggle switch. I make dioramas and miniatures and want to start using led lighting. I have an ornament from Hallmark that you plug into one of the mini light sockets of a Christmas light string (3.5v). The ornament has movement and light.
I have cut and wired it to run on a battery without the light. I want to add an led. How do I go about calculating for the resistor. My common sense tells me I would have to figure in the amount of voltage the mechanical part is using. Am I right on this? I want to use a 9 volt battery. Thanks in advance for any advice you can give a newbie.

2. jasonben

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Jul 15, 2009
I don't know. However, I hooked up a motor to battery and noticed the readings change as I applied more pressure to the moving part. I don't remember what I was measuring - volts or amps. I imagine that moving parts might have complicated effects because they might resemble generators in structure and function.

If you make the circuit closed without a battery, you might even be able to manually move the moving part enough to generate a current to light the led.

Most of the bulbs that I have come across are not polar. I'm not sure if I am using the word polar correctly. However, I think that LEDs are polar. You might want to look up anode and cathode - if you don't already know what they are. If you research schematics for a resistors and an LEDs, you might notice that LED schematics are less symmetrical - and this has something to do with polarity - that the sides of the LED can be hooked up interchangeably.

If you aren't getting answers as quickly as you would like, in addition to any useful experiments that may or may not be too complicated to perform at this time, you might research what information is provided about motors when they are sold. All of this information may be written on parts in the ornament or motors that you may come across. This may be the most important information for practical use of the components.

Things that you may learn include Ohm's law, how to add resistances of LEDs in series and parallel, and Kirchhoff's Laws. I remember reading that there are advantages and disadvantages to both connecting LEDs in series and parallel - though I don't remember what they are.

It may be important to consider whether to hook the circuit up in series or parallel. There are some simple explanations of what series and parallel circuits are on the web. You may eventually find this one useful: http://www.hebeiltd.com.cn/?p=zz.led.resistor.calculator.

You may also decide that it is appropriate to research threads or start new threads for any of the things mentioned.

Last edited: Aug 12, 2009
3. cat50

2
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Aug 11, 2009
Thank you for the reply. I do understand Ohm's law and will read up on Kirchhoff's Laws. The motor was already in the ornament and I have no specs on it. What I did was cut the electrical wires and rewired it to use with a 9v battery. What I would like to do now is add an led to light up the diorama. I know what resistor to use but don't know if and how the motor affects the values of that resistor. I will check out the link. Thank you for your help.

4. jasonben

22
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Jul 15, 2009
I can't guarantee that your set up will not shorten the life of the motor or cause a fire if left unattended after a while after it was started. What do you mean by values of the resistor? How much power is dissipated? I don't know a whole lot about LEDs except that their values are dependent on the conditions of the circuit - conditions which I think that the motor might change. So, it seems to me that the values of the resistor might be dependent on the specs of the motor. It may be that the motor cause the electricity in the circuit to alter in such a way that would cause the LED brightness to vary or burn out without a component to steady this effect. I'd learn about how motors effect circuits - perhaps by researching threads and/or starting a new post. Wikipedia is a good source. It may be that components are needed to steady the effects of generators. At this time there is also an active thread about LEDs that you may find useful - or a good place to ask questions. You might also consider contacting hobby shops that sell products with both motors and LEDs - such as model railroads, etc.