ph2t

[ph2t]

The site I link most of my doc/pics and stuff to in these threads is maintaned by me. If you want to move them and/or setup a permanent area for tech goodies just say or PM me.

cheers,

ph2t.

[ph2t]

shypo, you’re a smart arse pimp mutha! lol! :D:D

[ph2t]

Thanks to some very resourceful germans, I’ve managed to get the datasheet for the TX2/RX2 chipsets. This will make for some damn fine reading for all us techies out there. (I bet uA would be salivating already…:smiley2:)

Get it here.

ph2t.

[ph2t]

The Bensu clone I developed this on uses the TX2/RX2 chipsets…. (first revision B)

Just moved house so I have to unpack all my stuff to start checking this……..

ph2t.

[ph2t]

diets, wow! you have opened up another stage of development for me. I have tested steering by itself and throttle buy itself. But not together! hmm……….

Efarel and Jamie, please let me know how you guys go with this.

ph2t.

[ph2t]

Guys,

forum.doom9.org has a great DV Forum on capturing and editing.

Cheers,

ph2t.

[ph2t]

Yeah the throttle frequency can be changed, and to tell you the truth it could probably be increased. I haven’t tried this yet and I don’t know how high you could go until the signal just drops out. Keep in mind that these controllers use an OOK (On – Off Keying) transmission scheme to encode exactly what it wants the car to do. If the freq is upped too much, it might negate this OOK scheme to crap. The steering once in production will look kinda jerky. It’s like tapping the L-R buttons frequently to get a slight turn instead of a full turn which is just holding the L or R button down fully. Unfortunately nothing can be done about this since the steering is magnetic. I’ll pull my finger out of my arse and do some video once we move on the weekend.

The way to calibrate the controller is to centre the pot (be it steering or throttle) and then adjust the trimpots until there is no signal for both L/R or Fwd/Rev. You then turn the pot just slightly and adjust the trim until the signal starts working. The values of the other resistors ensure that turning the pot to the extent of its arc will result in a full “ON” signal going to the controller. (The same as pressing the button fully)

When used on a daul bat bit, this controller is even better. I can start off the mark without any wheelies at a lower speed and then gain full speed for some real action.

Hey Efarel, thanks for the praise :), but you might want to check the circuit on the controller of the Auldey to make sure that the pressing of the button on the controller equates to the same action as bringing the pin to ground. Although with the use of the 4N25 opto-couplers you could pretty much substitue these pins (5 & 4 on the 4N25) for the push button. Just make sure that the polarity is correct because the light dependant transistor in the 4N25 will only allow current to travel from Pin 5 through to 4 (being an NPN transistor and all…) You can ignore pin 6, it’s not needed.

Again, here are the videos of my testing.

test1
test2
test3
test4

ph2t.

[ph2t]

Thanks 😀

But we should wait till tha fat lady sings….

ph2t.

Edited by – ph2t on 27 March 2003 15:17:06

[ph2t]

The throttle is proportional in both directions(Fwd & Rev).

When the pot is centred there is no signal (the trimpots R13/R15 are used to tweak the centre position for no signal). This is the same for the steering (in this case the trimpots R21/R29 are used to calibrate the centre, neutral position).

Looking at the schematic I will explain it in portions.

1) Triangle wave generator:

U1B & U1C (parts of the LM324 quad op-amp) form a triangle wave oscillator at a certain freq. This part drives the throttle so its freq is about 30-40Hz (I think). This can be set by capacitor C1.

U2B & U2C are a copy of the same osc, but in this case the value of the cap C2 is greater for a lower freq. This drives the steering, I found the steering more responsive at a lower freq (approx 6 – 10Hz)

U1A is just a reference voltage source @ 3V. This is needed because op-amps usually are run off +ve and -ve voltage sources.

2) Comparator / Pulse Width Modulator

U1D & U2A take the signal from the output of U1C and compare it against a voltage level set by the potentiometer R12. I won’t go into too much detail here but when the voltage reaches a certain level @ the -ve input of U1D & U2A it outputs a positive voltage. (Bugger, this is hard to explain:dead:. I might need to draw some pictures) This is why a triangle wave generator is used. As you turn the pot R12 it varies the width of the pulse seen at the output. Hence the name “pulse width” modulator.

The daul-gang pot (R12/R25) is the part that makes it all happen. You will see that each side of the pot is wired in opposite direction. ie: I turn the pot one way causes one voltage level to increase and the other to decrease. It is this that gives you both directions.

3) Output stage

The outputs of U1D & U2A both drive the opto-couplers which then in turn drives the transistor allowing for the pin for the TX2 chip on the controller to go to ground. At first I didn’t have the opto-couplers and I was finding it hard to “pull” these pins to ground properly.

Stages 2 & 3 are duplicated for steering AND throttle. It is really stage 1 that differs (and then only in the value of caps C1 & C2).

Sorry for such a braindump, but you asked :smiley2:.
I’m just waiting for uA to get back from his holiday so he can read this!:)

ph2t.

[ph2t]

Yes I have built this and it does work. I have video of the speed control in action in the tinyrc thread. I tested the steering as well and it works too(although I don’t have video of this). I used the opto-couplers and this improved the control to the steering. I have bought some veroboard to put the whole thing together and get away from the birdsnet I’ve created.:approve:

I’m moving house at the ‘mo so development is sort on hiatus until next week.

ph2t.

[ph2t]

Jamie, go for it man! :smiley16: I’m more than happy to help, you can get all the parts from either Jaycar or Dick Smith Electronics. I’d like to keep the main development still here at tinyrc. It’s just easier to maintain that way.

Crom, yes this is it. when I get the time over the next day or two I’ll write down a detailed explanation of how it works. Although the principal is explained in detail in the original thread. This thread includes video and pictures of a very messy prototype. Give me a few weeks to get one lookin tasty…

yo Shypo (you pimp! :smiley2:), this is my proportional controller emulator. It provides very good speed control (fwd and rev) and not-to-shabby steering control. The steering is good for really slight turns and varying arcs, also times for when your thumbs just can’t hack it!

The goal is to get it into a pistol-grip like controller. I can then piggy back whatever Freq controller I want to it and take it from there.

[ph2t]

yeah, graphics is all stuffed though. Tiny is gonna be a busy boy!

[ph2t]

Damn, still down….:dead:

[ph2t]

Damn, still down….:dead:

[ph2t]

thanks z-beam, if only my day job was as supportive as you :smiley2:

ph2t.

[ph2t]

A mate of mine is a member of the Prahran Club. It’s a nice big hall and it has a bar!!!! We’ve had some pc meets there in the past. I’ll talk to hime and see if I can set something up. To be realistic about the timeline, well it wouldn’t be for a couple of months. And there might be a donation of a few bucks to the club to cover operating expenses. But, it’s huge. We could setup one nice big track. Might even bring my webcam……………

Let me know what you guys think.

ph2t.

[ph2t]

doosh doosh doosh doosh!

[ph2t]

Very well observed Efarel :). I just bought myself four 4N28 opto-couplers to include in my design. I had trouble with the steering inputs in the TX2 chip no fully going to ground when connected to the output stage of the comparator. Using these opto-couplers should do the trick.

Cheers,

ph2t.

[ph2t]

z-beam: the blue isn’t the slowest, but I have to set some time aside and do some testing with these motors in the same car over a set distance and see what happens I guess.

I was hoping to suck any collective wisdom I could from you guys…

micro: you just can’t help yourself can you :approve:

ph2t.

[ph2t]

Quote:

For a purely social ‘meet and greet’ session, I think a pub would be fine.

That’s what I’m thinking…. Meet first, get pissed, slag each other and make spurious comments.

Then race!
:smiley16:

ph2t.

[ph2t]

Hey GT, just wait till my propo controller is finished then you’ll have some serious drifting action! :smiley2:

ph2t.

[ph2t]

Hey KITT where did you get the mod from? Mikes Mods??

Cheers,

ph2t.

[ph2t]

They’re just clones, to die for the cause……..:evil:

[ph2t]

Hey guys, for all the Melbourne based turkeys I’d like to organise a get-together some time in a few weeks. Not for racing, just more of a get-to-know-you sort of thing.

What’s everyones thought on the matter? Do we want to meet at a pub? Or is there an issue with ages?

I was talking to Micro_amps about this today and it sounded like a good idea. The Sydney people seem to be getting things going, I’m sure Melbourne can too.

Let me know,

ph2t.

[ph2t]

Is this wax you are refering to? You need to melt this off (I soak it up with some paper towling whilst it is melted) before you can safely turn the ferrite core.

ph2t.

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