Bluetooth Resistors - Page 1
Forum section: electronics / projects

author: aerovtp
author_rank: Newbie
timestamp: January 16, 2014, 06:57:16 pm
content: I am working on a DIY project at home where I am trying to get a variable resistor, ( an on and off resistor would work to), and control it through bluetooth. The setup is made so that I want the resistor to have bluetooth built in though, I don't want to have to do something like adding an arduino with bluetooth to control it. Has anyone heard of a product that will allow me to directly control the resistor through a smartphone with bluetooth enabled?Thanks in Advance,AeroVTP

author: MatCat
author_rank: Frequent Contributor
timestamp: January 16, 2014, 07:30:11 pm
content: A resistor is a passive component, not a controllable device. Think of it like water in a pipe, the higher the resistance the tighter the pipe gets, therefore less electrons can pass (In this case it would be current).What is that resistor supposed to be hooked up to? Resistors by themselves would be quite boring if just turned on and off...

author: dannyf
author_rank: Super Contributor
timestamp: January 16, 2014, 07:32:56 pm
content: QuoteAn on/off "resistor" controlled via bluetooth.That's as useful as a toaster that vacuums the floor.

author: aerovtp
author_rank: Newbie
timestamp: January 16, 2014, 07:52:06 pm
content: The resistor is connected to a motor. It would be wonderful to just connect it to an arduino or other system and use a wire. Unfortunately, my idea requires about 10 motors to be spread out around the house and I want to be able to control all of them without having to buy 10 microcontrollers. However, if I were able to get a bluetooth resistor that allowed me to control the speed of the motor from a smartphone, it would be cheaper and a better solution.I'm sorry, I feel as though the comment about the toaster and vacuum is supposed to put me in my place and make me feel stupid but I don't really get it.Good TryThanks to the first person who replied,AeroVTP

author: Zero999
author_rank: Super Contributor
timestamp: January 16, 2014, 08:01:55 pm
content: It would be better to use PWM to control a motor.You would need a separate MCU for each motor and a receiver but it wouldn't need to be a powerful MCU.

author: free_electron
author_rank: Super Contributor
timestamp: January 16, 2014, 09:16:20 pm
content: Your explanation fits like pliers on a pig.What do you wan to control of the motor ? The speed ? The torque ?What kind of motor ? Ac ? Dc . Brushless ? Induction ?Does the motor have a controller that uses a resistor to set the speed ? What value is it?You cant just use 'a resistor' to control a motor. There is a bit more needed than that.So, give us some more info ok ?

author: dreaquil
author_rank: Regular Contributor
timestamp: January 16, 2014, 10:21:09 pm
content: when you say on or off switch for the resistor... couldnt you just use a transistor to switch open or close the circuit/ short it using some controller? all I can think of though is a microcontroller...

author: zapta
author_rank: Super Contributor
timestamp: January 16, 2014, 10:28:27 pm
content: Bluetooth modules like this one have io pins that you can control wirelesly.https://www.sparkfun.com/products/12574You can connect them to an analog switch multiplexer ic to select one of several resistors or find one of those digitally controlled potentiality chips that already include the resistors and has a parallel input.You will need to find the components and configuration that matches your specific application. This is just an outline.

author: MatCat
author_rank: Frequent Contributor
timestamp: January 16, 2014, 10:34:49 pm
content: There just isn't enough info to give any sort of advice here. Like free_electron said, there is much more to running a motor then just a resistor, plus most motors if just ran from a MCU with a resistor will probably just fry your MCU trying to pull too much current, unless this is a really small micro motor.Honestly if you don't even know exactly what a resistor is you should probably learn a bit more about electronics, I recommendhttp://www.amazon.com/Make-Electronics-Discovery-Charles-Platt/dp/0596153740/ref=sr_1_1?ie=UTF8&qid=1389911632&sr=8-1&keywords=learn+electronics,the Make Electronics book, it was the first one I read and gave me a good foundation to go from. I am sure others could give good book recommendations too.

author: grumpydoc
author_rank: Super Contributor
timestamp: January 16, 2014, 11:27:28 pm
content: I can only echo what others have said - you need to understand some basics so that you can ask a meaningful question.QuoteOut of curiosity have you thought about what happens when "The resistor is connected to a motor"? Youcancontrol a brushed DC motor's speed with a resistor (well, this is one place I'd actually use the term rheostat) but it isn't a great way to do so because adding a resistor reduces the current through the windings which then reduces the torque so with any load it's very difficult to really get any speed control.There are other types of motor as well - DC brushless, stepper, AC motors of various kinds - any of these might be better suited to your idea but we can't advise as we don't have enough information to go on.Also think for a moment about your statement "... I want to be able to control all of them without having to buy 10 microcontrollers. However, if I were able to get a bluetooth resistor...".Bluetooth is a pretty complex wireless protocol so however much you want to avoid a microcontroller per motor you aren't going to do it. All those bluetooth gadgets - speakers, keyboards, remote controls, whatever have a microcontroller (or something as complex) in them to handle the bluetooth communications.Finally you say "Unfortunately, my idea requires about 10 motors to be spread out around the house". Bluetooth is a "personal area network" - it's designed to work with devices in the same room, not scattered around the house so you aren't going to be able to reliably controll all the devices from one spot with bluetooth.You might be OK with that and say "well I just want to control a device if I'm in the same room" but I have to say that my experience with bluetooth is that it isn't always that great when things move in an out of range a lot - you wind up forcibly re-pairing devices to get them to talk to each other which is not great if you just want to wander into an area and do things with the devices there.Forget "bluetooth resistors" - if you describe what you wish to achieve and ask for ideas on how it might be done you will get a better response.For example if you say "I want to be able to open and close the curtains in each room using my phone" - that would be a good start. You might go on to say "I have found some motorised units and my phone has bluetooth - is there any way to control the motors using bluetooth" but only if you have told us what the grand plan actually involves.

author: Macbeth
author_rank: Super Contributor
timestamp: January 17, 2014, 06:29:41 pm
content: Quote from: MatCat on January 16, 2014, 10:34:49 pmHahaha! That book looks great! I particularly approve of the 9V battery tongue test! My always first choice 'meter' even to this day when testing the charge in those things!

author: electronics man
author_rank: Frequent Contributor
timestamp: January 17, 2014, 10:38:35 pm
content: You should try xbee it is so easy to use and you can avoid the use of a an MCU using its gpio. If you want an electrically controllable resistor you could use a digital potentiometer I feel this is a bad idea you should use PWM but you will need to use an MCU for that. If you don't have experience whith them then try picaxe it it is easy to get started with and is comparable with xbee.

author: grumpydoc
author_rank: Super Contributor
timestamp: January 17, 2014, 11:16:37 pm
content: QuoteHe won't be able to connect a digital pot straight to a motor though.Well, he can but it won't work

author: electronics man
author_rank: Frequent Contributor
timestamp: January 18, 2014, 12:47:23 pm
content: Well it's the only way you can digitally control a resistor so I think he should not use this method. Why not just a PWM or a variable voltage mabe from a digital pot connected to a Darlington transistor

author: dannyf
author_rank: Super Contributor
timestamp: January 18, 2014, 02:22:37 pm
content: QuoteNot sure. I would think that a bluetooth-controlled on/off resistor would have a lot of potential to win as the most ineffective and most convoluted solution that almost solved a simple problem.From that perspective, it works wonderfully.

author: electronics man
author_rank: Frequent Contributor
timestamp: January 18, 2014, 05:14:08 pm
content: Lets just help aerovtp complete the project mabe using a diferent method.I would like some clarity. I would like to know what the motors are for and what aspect to controll, I gues it is the speed. But I need more info

author: dannyf
author_rank: Super Contributor
timestamp: January 18, 2014, 05:23:14 pm
content: There us certainly value in helping the op solve this problem.however I suspect there is far more value to the op if we help him learn to approach problems.