Show Posts
Pages: 1 2 [3] 4 5 ... 17
31  Using Arduino / General Electronics / Problem using a voltage divider to input a voltage to a low impedance line on: July 23, 2012, 08:39:01 pm
I had a problem using a voltage divider to input a voltage (between 0 and 12 volts) to a low impedance signal line. I used a potentiometer as the voltage divider, and as I turned the pot the signal voltage would suddenly jump from around 1 volt to over 10 volts. So that did not work.

My new plan is to use a TIP120 transistor to send the voltage signal. I'll use an Arduino analog PWM output to the transistor's gate, and put ground and +12 volts through the transistor. By varying the output from the Arduino from 0 to 255, I hope to get the whole range between 0 and 12 volts. 

Will that give a good voltage signal on the low impedance signal line?
32  Using Arduino / General Electronics / Re: Where can I buy RJ45 female connectors? on: July 12, 2012, 10:51:51 am
Thanks, MarkT. You are right. At Digikey I searched for USB receptacle, and there they were. It's nice to learn to be posher.
33  Using Arduino / General Electronics / Re: Where can I buy RJ45 female connectors? on: July 11, 2012, 10:07:49 pm
Oops, my mistake. I said RJ-45 female connectors, but what I was having trouble finding was USB female connectors. Jameco has them. Digikey and Mouser do not seem to.

And keep in mind some have integrated isolation transformers ("magnetics") that you'll want to avoid.

Thanks for the heads-up about the magnetics. I wondered what that meant.
34  Using Arduino / General Electronics / Re: Where can I buy RJ45 female connectors? on: July 11, 2012, 08:22:02 pm
Found them at Jameco. I knew that would happen. Whenever I give up and post, I find the answer shortly thereafter.
35  Using Arduino / General Electronics / Where can I buy RJ45 female connectors? on: July 11, 2012, 08:06:34 pm
I'm working on a project where I use Cat5e cable to send four digital signals from an Arduino to some electronics about six feet away. I have the Cat5e cable that I need, with a male connector on one end.

What I need, though, is the RJ45 female connector to go with the electronics. I want to mount that connector on perfboard and run wires from the connector to some transistors and other components.

I thought those connectors would be easy to find, but can't find them anywhere. Any suggestions on where to look?
36  Using Arduino / Project Guidance / Re: Ok, I finished an Arduino project. How to make it permanent? on: May 14, 2012, 01:13:06 am
Let me second Coding Badly's suggestion of the Teensy. They cost $16 but they work really well if you need the serial over USB function. The other option I have used to buy a cheap USB programmer off of eBay and use it with an RBBB (Really Bare Bones Board) Arduino. That ended up costing about the same.

Adafruit sells a board for $20 that is similar to the Teensy. http://www.adafruit.com/products/296 But I could not get that board to work with serial over USB. (Plus I had a real tough time programming that board. The Teensy was much better.)
37  Using Arduino / Project Guidance / Re: Motorcycle loom on: May 04, 2012, 12:47:45 pm
That's an interesting project. We converted an old pickup to an electric car, and replaced the wiring harness with a network-type setup. We use a Teensy (not an official Arduino, but like one) at each "corner," and connect the lights, horn and other accessories through a 4-relay board that is switched by the Teensy. It works well, replacing a complicated and heavy wiring harness with a simple network.

On a motorcycle, it might not work as well. Especially if you have all the wiring for the gasoline engine as well. You probably would not get the simplicity we can get, and since the distances are shorter on a motorcycle, the cost-benefit ration may not be in your favor.

Certainly it would take some effort. But it could be done, and you would learn a lot if nothing else. Whether you want to do it or not, only you can decide.
38  Using Arduino / Motors, Mechanics, and Power / Re: Controlling servo without needing to use delay on: May 01, 2012, 12:49:00 am
I can attach a YouTube video if this is still unclear.

A video would help.
39  Using Arduino / Project Guidance / Re: pc keyboard with arduino? on: April 17, 2012, 01:42:38 am
The Teensy may work well for you. You can get one for $16 from www.pjrc.com. They also have a code library at that website for USB keyboards: http://www.pjrc.com/teensy/usb_keyboard.html
40  Using Arduino / Motors, Mechanics, and Power / Re: Interference with wiring on: April 12, 2012, 11:15:14 pm
Good to hear that solved the problem. MarkT was right. I must admit I was wrong--I never thought that would be the cause. Always good to learn something new.
41  Using Arduino / Motors, Mechanics, and Power / Re: Interference with wiring on: April 12, 2012, 06:27:05 pm
Although I cannot rule it out, I doubt that wire shielding is the problem. Certainly, as suggested, you may want to getting a better cable. Even a USB cable would work.

You said that if you unhook up the 12 Volt supply to the motor controller, things work. If you do hook up the 12 Volt supply, things do not work. Is that even when no current is flowing to the motor controller? In other words, when the motor is not on?

The reason I ask about the pot input pins is that I think that is where the problem lies. I don't think your Arduino is reading the correct value from the steering pot. If you could confirm that by testing, that might help. You could hook your computer up to the first Arduino, have it read the pot input pins, and then have print out the values to the serial monitor.
42  Using Arduino / Motors, Mechanics, and Power / Re: Interference with wiring on: April 12, 2012, 12:49:35 pm
That is a tricky problem. As I understand it, when you connect up a 12 Volt supply to a motor controller, that affects only one pot reading on an Arduino where the pot is connected to a separate 5 Volt supply. Is that right?

What connection is there between the 12 Volt and 5 Volt supplies?

Are all grounds connected?

Where is the code that reads the pots? Did you set the analogRead input pins to be INPUT?
43  Using Arduino / General Electronics / Re: Powering my uno on: April 10, 2012, 02:19:58 am
Dave, you probably know this, but just in case you do not.

If you plug the 5 Volt power into the barrel connector or the Vin pin, the power will go through the voltage regulator and will not be high enough voltage. You need at least 7 Volts to get a stable 5 Volts out of the voltage regulator.

If you plug the 5 Volt power into the 5V pin, the power will bypass the voltage regulator and will be high enough voltage to work well. Be sure to connect the grounds as well.
44  Using Arduino / General Electronics / Re: Powering my uno on: April 09, 2012, 11:37:52 pm
I'm not sure what Dave ("substance") had in mind either. But it sounded like he has 5 Volts regulated power available, yet planned on using 15 Volt power instead. My suggestion was, if that is indeed the case, to use the 5 Volt power.
45  Using Arduino / General Electronics / Re: Powering my uno on: April 09, 2012, 09:10:37 pm
"I have read the 5V supply will not be enough as it could lead to the unit becoming unstable."

That seems wrong. If your 5 Volt supply is well-regulated and can supply the current, it should work fine. But you don't use the barrel connector with 5 Volt power. It goes directly to the board.
Pages: 1 2 [3] 4 5 ... 17