Question 1

How many resistors come with each order?

Accepted Answer

Think the pack of a hundred, prolly had close to a hundred in it.

Question 2

Do these lower the voltage by 3 volts or what should i be looking for? i need to drop 6 volts to power a tamiya motor

Accepted Answer

You need to state what the rated current is for the motor, and the nominal voltage of your power supply.  I am not familiar with the motor you are using, but assuming it is a DC motor and for illustration we shall pretend it draws 30 milliamps at 3 volts, and that your power supply is rated at 6 volts DC, we can now calculate the resistance needed to dop the voltage for the motor.  To drop 3 volts across a resistor at 30 milliamps you would use the basic fomula V = IR where V is the voltage, I is the current, and R is the resistance.  To get R we divide V by I.  3 Volts divided by 30 milliamps give a resistance of 100 Ohms.  It is for you to work out your required resistance value from here.  Also, you need to consider your wattage for the resistor - wattage is the power being dissipated by the resistor.  P = VI where P = power (watts), V = voltage and I = current.  for my example, 3 Volts * 30 milliamps = 0,09 watts - a 0.25 watt resistor will be fine.  If you were dropping 3 volts across a esistor and your current was 0.3 milliamps, your 0.25 watt resistor would glow cherry red and then likely stat to burn - you need to consider the power rating of the resistor as well as the resistance value.

Question 3

Are these good for a 3v led light with a power source 0f 12-16v. It's for my model trains.

Accepted Answer

To properly answer your question we also need to know the current rating of your "3V LED Light".  If we assume the LED will work up to 20mAmps (0.02 Amps) and the LED truly drops 3V DC (I assume your voltage source is DC) then at 16V output of the power source with a 1Kohm resistor in series with the LED will supply (16V - 3V)/1000 Ohms or 0.013 Amps.  The dissipated power (dissipated as heat by the resistor) will be current squared times resistance, or 0.013 * 0.013 * 1000 or 0.169 watts.  The resistor is rated for 0.25 watts, so it should be fine (if a little warm).  In truth, there is probably also a little resistance in the LED Light if it works from a 3VDC source (like a pair of AA batteries in series) , so your actual current draw will be a little less than what I calculated.  You should be fine, but make sure the resistor can get rid of the heat.

Question 4

is it good?

Accepted Answer

Not sure what you might consider "good", but I myself was favorably impressed.  Very good quality, bright colors, very fine gauge and dead-soft annealed copper leads bright tinned, really easy to bend and shape for tight spaces, etc.  No complaints, no regrets.

100pcs 4.7K ohm Resistor 1/4w (0.25 Watt) ±1% Tolerance Metal Film Fixed Resistor, Multiple Values of Resistance Optional

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