132 replies to this topic

[LaMbChOpZ]

So I'm back for one reason, my CotA 2013 coaster. We're not dealing with LED's this time. I planned on using NXT for my coaster, but the servos could never lift that car up the lift hill. So now I'm looking to the next option, Arduinos. I don't have the strongest background when it comes to figuring the wiring of the system and what board to use (those go hand in hand I assume). I'm asking this now because the event is 9 momths away, leaving me plenty of time to take my time to get this to work.

Since I know this is important, this is what I'm looking to do wiith the program:
- control the lift hill (acceleration and automation)
- control the transport for the brake run that leasds to the station
- create and manage a block system so the ride can run "hands free" incase I need to go somewhere else in the building. This means I am looking into the use of reed switches or another type of small sensor.

I do have good knowledgw of C++ and Java, so when it comes to the code, I should be good. So I guess my first question would be, how do I go about this? Figure out the wiring first then choose a board, or vise versa?

[Witting]

Electronics look complicated to me. But i'm going to learn it in school. Lucky me

[Maxlaam]

I do have good knowledgw of C++ and Java, so when it comes to the code, I should be good. So I guess my first question would be, how do I go about this? Figure out the wiring first then choose a board, or vise versa?

Read into how you should control things with an Arduino. Relays, Servos, Transistors. And get used with/to the limitations of the board. (Aka, make sure to LIMIT your current!!, It can only take so much to completely fry a what used to be perfectly working microcontroller.)

It's important to know what you want to control and how many of it. Buttons, motors, etc. Then you figure out what board is the most suitable. If you are short on pins you can use a shift-register to add some outputs/inputs. Haven't messed around with that yet, so that's up to you to figure out if you need to use that.

[LaMbChOpZ]

^ OK thanks. I'll start a new thread for this mini-project so I don't blow up this thread with all my stuff.

[ForgotToGrowUp]

Just ordered a Arduino Mega and Motor shield off eBay.... Who knows what I'll get done with it but it is an interesting extension of the Knex hobby. Gonna have to dust off some long unused brain cells to do some basic wiring and microprogramming (actually have a 30 year old degree in electrical engineering but you know what they say, use it or lose it!). Initial plans are very basic motor controls for the brake run, station and lift. Probably use relays to turn main lift on and off use the motor shield (L293D based) for the brake and station motors. Not sure if I will use reed switches or just trigger switches for the inputs.

[maarten12]

Cool, someone else who is going to use and Arduino . I'm very curious to see what you are going to do with it Jeff!

[iCoaster44]

Sorry for bumping but I am starting in electronics.
How many 12V motors this PSU can power at the same time and still power LEDs, arduino etc without blowing everything ?

[Maxlaam]

Next to +12V it says how much Amp's it can supply on that line. 13.0A that's roughly 52 12V motors when they draw the highest current, which is when they stall out. (I measured something between 200mA and 300mA)
Furthermore 25A on the +5V line, plenty of juice to run all components that require 5V.

You have to do something really crazy if you want to get close to those limitations.

I do hope you understand that the question you asked doesn't actually have an answer. What is the stall/peak current of the motors? (You can use a multimeter to measure this or look at the datasheet from the moto.r) How many LED's do you want to drive? What other components are you planning on using?

I do suggest you read into the basics first and understand what current, voltage, resistance and power are, and how they relate to one another.

Edited by Maxlaam, 31 January 2015 - 03:28 PM.

[iCoaster44]

Actually, I know this PSU have plenty of power to deliver but it is about the quality of the PSU.
Sometimes, PSU deliver less. It is a ATE PSU so smaller so the components are more cranked inside (it is a 14 years old PSU).

Edited by iCoaster44, 31 January 2015 - 05:01 PM.

[Maxlaam]

Actually, I know this PSU have plenty of power to deliver but it is about the quality of the PSU.
Sometimes, PSU deliver less. It is a ATE PSU so smaller so the components are more cranked inside (it is a 14 years old PSU).

Well, then measure the output voltages and current. If your concern is it's age then that's what you can do. If it's damaged then discard it, but I'm not sure what you're on about with it's internals. It's a 250W PSU, everything you need to know is on the side as far as I'm concerned.

Just don't tamper with anything on the inside. When I got my PSU I let it sit for two weeks after testing it before opening the housing to clean some of the dust out using compressed air.

[ThisIsGabe]

^ I think your PSU should be fine. Unless you're really cranking the load, there's enough power in the system. The ratings are usually pretty well followed, so just use Ohms law (V*I=P) to make sure you don't overload the supply. If you did overload it, it would just power off.
If it can't supply enough power, just bin it and buy a new one. It'd cost more and take longer to boost the power of that unit than it would to just buy a new one. Plus power electronics are finicky at best, and as Maxlaam said it's very dangerous to go poking around inside.

Edited by ThisIsGabe, 31 January 2015 - 10:20 PM.

[iCoaster44]

I found that the 12V wires are 16 and 20 AWG. My wires are 22AWG. No problem ?

Edited by iCoaster44, 01 February 2015 - 08:39 AM.

[ThisIsGabe]

Not unless you're going to have a high load for hours at a time. AWG ratings assume constant load for near-infinite time.