Pull-up resistor (1–100 kilo-ohms)?

Support Servo controllers and servos
1

Does this mean 1 to 100 kilo-ohms or 1100 kilo-ohms? What would be the best resistor to buy?

Thanks

2

Hello.

I am not sure if you are referring to something on our web site or asking a general question about a pull-up resistor range, but “1-100 kilo-ohms” probably means 1 kΩ to 100 kΩ. The appropriate value depends on your particular application, but 10k is often a good choice.

-Robert

3

Thanks for the reply. I am talking about wiring the maestros to use a motion sensor. It asks for a pull up resistor and I was wondering what the best one to buy would be.

Thanks

4

“Next, wire a pull-up resistor (1–100 kilo-ohms) between the signal line of that channel and 5 V so that the input is high (5 V) when the switch is open.”

From this passage.

Thanks

5

So what would the best resistor be for this?

Thanks

6

Hello.

Your question has already been answered: something between 1k and 100k is probably fine. A typical choice is 10k. The details depend on the application.

Is there something more you are looking for?

- Ben

7

I quoted the Maestro User manual and asked what the best resistor would be. One answer is anything between 1 and 100 depending on the use and you just gave me the same answer.

Would it be best to use a 10 or 100 or a certain number based on wiring a motion sensor to a maestro? Sorry I need specifics. Last time I didn’t get specific I burned up 2 servos :slight_smile: my bad not yours of course as electronics confuse me. I am still trying to figured it all out.

Thanks
Luke

8

The reason you are not getting specifics is because in this instance, there is no specific answer: a wide range will work. The other reason you aren’t getting specifics is that you aren’t giving them. There isn’t some rule like “motion sensors require 32k pull-ups”. If there are going to be some additional constraints to consider, it will depend on what you are connecting and what you are trying to optimize.

Do you understand what a pull-up resistor does and how it does it? Have you read the Wikipedia entry on pull-up resistors? When you say “best”, what do you mean? (Best in what sense?)

- Ben

9

Using Pololu’s maestro servo controller and Pololu’s documentation and the passive infrared detector (PID) motion sensor SE-10 ordered from Pololu what would the best choice be? There isn’t anymore specific information I know of.

So a wide range will work, but is it better to use a resistor from part of that range?

Thanks
Luke

10

I guess I will go with the 10 kilo-ohm resistor?

Thanks
Luke

11

Yes, a wide range works, and 10k is fine; you just need something to set the voltage high while the output is open. You still haven’t said what you are trying to optimize, so I cannot tell you anything more specific.

- Ben

12

Sorry if I don’t communicate clearly but all I am trying to do is hook the pir motion sensor to the maestro per the users manual and it asks for a pull up resistor. There are no more variables I know of. It’s running a few hobby servos.

Thanks
Luke

13

Using a stronger (smaller) pull-up resistor will decrease the rise time of the signal, but it will also draw more current. I don’t expect you to care much about either of those things. If you had some particular constraints involving current or signal rise time, then maybe there would be a “best” value.

- Ben

14

So I went to Radio Shack to get a 10 kilo-ohm pull up resistor. Of course they had no clue what I was talking about and the resistors all had wattages and materials to choose from as well. I have no idea what to get. Does wattage or material matter?

Thanks

15

In the worst case, one side of the pull-up resistor will be at VCC and the other will be at ground. If you are using a 10k pull-up to 5 V, you can use Ohm’s law to calculate that it will draw 5/10,000 = 0.5 mA. The power dissipated by a resistor is given by I²R, so if I is 0.5 mA and R is 10k, you get that the dissipated power is 2.5 mW. Basically, any through-hole resistor you find will be fine (common ones are 0.1 W or 0.25 W). Material does not matter.

- Ben

16

Thanks