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Simple R/C Car Controls made usable
 Moderated by: W C Greene Page:  First Page Previous Page  1  2  3  4  Next Page Last Page  
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 Posted: Mon Jul 10th, 2017 07:51 am
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fallen
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Another useful microcontroller variant is the PICAXE which is like the PIC, just a controller chip that needs to be built into a circuit, but can be programmed in BASIC using (free) software running on a PC, which is a lot easier than assembly language, or c for those not versed in it.

BASIC Stamp is a similar idea.

Frank

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 Posted: Mon Jul 10th, 2017 09:22 am
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Helmut
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The last few posts give me a justification for sometimes sticking with 'dated' approaches:
You need knowledge of programming, you need the infrastructure for that if you want a small footprint or you have to accept at least credit-card sized 'intelligence', not to mention the space needed for the high-current stuff.
On the other hand, you just rummage in the electronic parts box, have the thing put together in short time, and need not bother with reprogramming should the parameters not satisfy you. Changing a resistor or a capacitor takes less time than changing the code and reprogramming the device. Especially those OpAmp-based approaches work right off the system voltage ( i.e. you use for your motor ) whereas the chips need their special 3.3or 5V, and then you need that interface into the real world, too.
Unless you go for multiple functions, sound or whatnot ( all completely out of scope in this case ), simple solutions that can be put into realization also by those whose second hobby is not microcontroller code-writing, still have their rightful place in the hobby.

Last edited on Mon Jul 10th, 2017 09:23 am by Helmut



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 Posted: Mon Jul 10th, 2017 01:24 pm
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Michael M
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Helmut,

Well put.  If it takes more than two wires to install I'm going to be in trouble since I'm electrically challenged.  I'm installing BPRC in a rail truck right now, and using the electrical parts from a RC car that I picked up for $6.  I just don't have the patience to learn code and how to program a chip.  My wife makes fun of me since I'm, 'cell phone' challenged.



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 Posted: Mon Jul 10th, 2017 02:24 pm
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W C Greene
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Like all things these days, even making a tiny locomotive run with r/c can be frustrating...if you read all the "info" and don't just do it! The inexpensive r/c equipment (as I have) works just like the high dollar stuff, and if you fancy sound effects (I don't) then such can be made to operate with the lower cost (and easy to install & use) r/c gear. Years back, I bought a TSUNAMI DCC sound board and installed it in one of my Shays. It did provide the chuff chuff and if I had cared then I could have figured out how to make it woo woo and ding ding also (remember that I dislike sounds). After a few minutes of running back and forth, I took the board out and later sold it to a friend. But I proved (basically to myself) that it was possible.
So, I will continue to run my locos with the ancient systems that are frowned upon these days...blissfully ignorant of electronic BS and courses in electrical engineering.
I'm not putting others down, just letting everyone know (as I did so long ago here) that simple works and works just fine.

Woodie

PS-Michael  What I use takes 4 wires...2 to the battery and 2 to the motor and the antenna wire becomes a "hose" along the running boards.



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 Posted: Mon Jul 10th, 2017 03:08 pm
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Michael M
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Woodie,

That's just what I do; 2 wires to battery & two wires to the motor.  It worked in my 1st loco, and I should have everything installed on the rail truck today.  Again, 2 wires here & two wires there.  I'm happy.  But, I'm always looking at new gizmos as long as they're simple.  On the rail truck the antenna will get hidden in the cargo box.



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 Posted: Mon Jul 10th, 2017 03:18 pm
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bobquincy
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Being somewhat lazy (noted in a previous post) I like the easiest path. If I want to blink an LED then a 555 or 3909 is my choice. However, if I want to blink two separate LEDs sequentially in a special flash pattern that will take at least four cascaded 555s and more than a dozen passive components then a single 8-pin PIC looks like a better (easier, cheaper, smaller) way to go.

Likewise I may use a 3D CAD system to design a complex part but for the simple ones a pencil and paper is quicker (and never crashes). :) For some of my projects (like "autonomous") there really is no other way than a microcontroller but I certainly see the point of those who prefer the simplest wiring possible.

I like that our hobby is fun for those who connect two wires from a power supply to the track *and* for those who write a few hundred lines of code to see a train perform a special function. There's even room for those who prefer a single rail over two (or three)! :)



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 Posted: Thu Jul 13th, 2017 07:02 pm
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bobquincy
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Here is my circuit to convert a bang-bang on-off control to a smooth ramped start & stop, someone may find it useful.  The "REMOTE" in the circuit is Disney's Mark VII monorail, typical of on/off types where in forward the FWD output is connected to B + and REV is connected to B -, opposite in reverse.

The "DRV" board is required anyway as the original outputs are limited to about 250 mA, not enough for a decent motor (on 2.5 V).  The brains of this circuit is the PIC 12F1572 which goes between the on/off outputs and the DRV8835 motor driver to provide the smoothly increasing/decreasing Pulse Width Modulation.

If this does not look easy I can make it a little easier: if anyone wants to try this I can provide a programmed PIC for my cost (less than $2 including postage).

Specifics: (this version is made for a train that is powered by 2xAA batteries.  It can be revised for higher voltage)
   PIC requires 2.5 to 5 V
   inputs FWD and REV are at B + when active
   Pololu DRV board requires 0 - 11 V, logic 2 - 7 V
   3.3 V converter only has to provide power to the PIC, LED, and VCC, maybe 20 mA total
   PWM frequency is 120 Hz, it can be changed

    zero to full speed takes about 3 seconds, the time can be changed

The headlight output is on steady in FWD, flashes in REV (can be changed)




larger version at:   http://monorail.suzieandbob.com/images/mark%20vii%20soft%20start_schem.jpg

Last edited on Thu Jul 13th, 2017 07:11 pm by bobquincy



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 Posted: Fri Jul 14th, 2017 08:16 am
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Helmut
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@Bob
Have you included a 'hold' feature in your control? That is, the speed ramps up/down only for as long as the respective button is pushed, and keeps the attained speed after it is released. So one can have any setting between 0 and 100% FS.



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 Posted: Fri Jul 14th, 2017 01:17 pm
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bobquincy
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@Helmut,

the original remote board latches the outputs when FWD or REV is selected and clears the outputs when STOP is pressed.  The way the PIC is programmed is to accelerate as long as an output is latched until the train reaches full speed.

If the remote board did not latch it would be simple to program the PIC to accelerate until the output was cleared and to hold whatever speed it reached until STOP was pressed.  As it is the PIC could be programmed to accelerate in FWD until STOP is pressed, then hold the speed until REV was pressed to make the train decelerate.  Once stopped it would look for STOP to be pressed before looking for FWD or REV again.

As we used to say at work to annoy the IT people, "it's just software, how difficult can it be?"!   ;)

Eventually I will program a microcontroller to take the place of the original remote board so I can have more options.



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 Posted: Fri Jul 14th, 2017 03:56 pm
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Bob R
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Not sure if it is just me or not................but seems we are way beyond "simple" R/C car controls in this discussion.  Once you get to this stage the simple DelTang appears to be a great option.  Unless of course you are a dedicated micro electronics hobbiest as well.
Woodie's simple R/C car controls appear to me to provide the max in cost versus enjoyment.  
There are also a lot of very small ESCs and receivers available for micro R/C aircraft.  The older 72 band stuff is dirt cheap on the used market since everyone has gone to 2.4 ghz and switched to brushless motors.  That has made this stuff practically worthless to airplane guys.  With 50 channels to choose from you will never have frequency conflicts.
Picture shows an Electrify 5 Amp ESC with 3.7 volt minimum and a Alpex Hobby 4 channel receiver.  Fully proportional R/C.  These are about 20 years old.  GWS was another popular brand to look for.  Newer stuff is much smaller and used is still quite cheap.  Replace the wires with some smaller gauge stuff and throw away the plastic cases and they will fit many applications.

Attachment: 20170714_104442_resized.jpg (Downloaded 34 times)

Last edited on Fri Jul 14th, 2017 04:00 pm by Bob R



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