Can It Be this SIMPLE? (the Off-Topic continuation)

[Mike_Lynch]

OK I have a Childs Electric Powered GO KART, ( Peg-Perego / Power Wheels type thing ) that I'm doing a
REBUILD / HOP-UP on for my 3 year old nephew. The thing came with a single 6 Volt battery and runs
forward by pressing a button on the steering wheel. I'm adding NOS / Turbo by installing a second
6 Volt battery in series. ( Insane I know but see this site http://www.modifiedpowerwheels.com/ ).
Also Wired in a switch for a powered reverse.
( see MY circuit and explanation at http://home.comcast.net/~david.lynch1/GoKartCkt.html )

Anyway I'm posting here with a question about some code I just hacked out to controle a
6 Volt ONLY "Soft Start" so the little one can't hold down the "NOS / Tutbo" button and step
on the "GAS Pedal" & end up launching form a dead stop to 12 Volts in an instant.
On the matter of 12 Volts burning up the motor, word is that most of these motors are 18 Volts.

My thought is to use a PIC12F675 to check voltage at the motor & if it's 6 or 12 volts
then it's OK for the "Go Faster" button to be pressed, the PIC needs to do nothing
except loop back to check again. BUT, if the motor voltage is 0 (zero) then the thing
is standing at a stop and if the Go Fast button is pressed when the gas pedal is pressed
I want to use a relay to disable the 12 Volts for some period of time, and allow the thing to
start at 6 Volts then release the relay and apply the full 12 Volts

Now ASSUMING that I have all my registers set properly and constants and variables
declaired, is the CODE as SIMPLE as this or have I COMPLEATLY missed it?

start:
	ADCIN 0, Motor_Volts

	If Motor_Volts > 0 THEN start 	' do nothing as SOME voltage exist at the motor
					' and we really don't care if the voltage goes from 
					' 6V+ to 12V+, that is what it is intended to do
	
	ELSE
		IF Motor_Volts = 0 THEN Delay_12V
	ENDIF

	GOTO start			' do we NEED this statement?

	END
	
Delay_12V:

	Motor_V2 = Motor_Volts

	WHILE Motor_V2 = 0		' as long as the motor voltage is at zero volts
					' we want to engage the RELAY which disables
	HIGH 12Volt_Cancel_Relay_OutPin	' 12 Volts from getting to the motor so we do not
					' have a HARD start from zero directly to 12 Volts
		
	ADCIN 0, Motor_V2
	
	WEND
             
        PAUSE 3000

	LOW 12Volt_Cancel_Relay_OutPin
	
	GOTO start

[sayzer]

First of all others,

It is very difficult to get 0 volt on the motor.

It might be done by short-circuit on the motor terminals but it is not safe for the motor. The motor life will be shorther then the life of a butterfly.

A powerfull resistor on terminals could be useful but again you will not get zero volt.

You may want to adjust that part a little by experimenting.




Word History: Is a butterfly named for the color of its excrement or because it was thought to steal butter? It is hard to imagine that anyone ever noticed the color of butterfly excrement or believed the insect capable of such theft. The first suggestion rests on the fact that an early Dutch name for the butterfly was boterschijte. The second is based on an old belief that the butterfly was really a larcenous witch in disguise.
How about that?

[Luciano]

Hi,

Wear a safety helmet!

With a full-face helmet or an helmet + protective chin cup
you will also provide protection to teeth.

Be careful!

Here the button "Go Faster" under the table was pressed!


* * *
What about using the PWM of the PIC?

Versatile DC Motor PWM Speed Controller:
(This example does not use a PIC to generate the PWM).

Part 1:
http://sound.westhost.com/appnotes/an009.htm
Part 2:
http://sound.westhost.com/appnotes/an009-2.htm

By using the PWM of the PIC you can set the right speed for the
child using the toy. (Next year you can set an higher speed).

This is done by changing the PWM duty cycle. By changing PWM duty
cycle you can set the motor to any speed and therefore create any
personalized acceleration curve.

(You will need a PIC with hardware PWM).

Best regards,

Luciano

[Melanie]

If I was a three-year-old, I'd want to experience the joys of burning rubber from a standing start... pass the 24v truck batteries... (then they can grow up and build drag-racers)...

Why bother with a PIC with the associated problems of Power Supply and Motor noise etc etc? Just a time-delay relay that enables operation of the turbo button a few seconds after power has been applied.

[Luciano]

..... experience the joys of burning rubber from a standing start...

I am not sure she would agree with you....


Luciano

[sayzer]

... (then they can grow up and build drag-racers)....

Why wait to grow up?

[f_lez]

If I was a three-year-old, I'd want to experience the joys of burning rubber from a standing start... pass the 24v truck batteries... .

My daughters 3 and a 1/2, her charger recently died, so I just swapped out the 6v batter for a 12v 17amphr one from a portable car starter, she's soon learned best way to set off is to stand up on it and lean forward........

she be in moto cross in a few years time I'm sure!

[Mike_Lynch]

Luciano.
First, do I even want to know what someone was doing “Going Faster under the Table” ?
Secondly, thanks for those links, I wonder If I could getaway with placing TWO
Variable Resistors in the circuit and using a relay triggered by the “Turbo” button to
switch between them? I’ll have to look into that as a possible solution.

“Next year you can set an higher speed.”
Good Idea if I could expect this thing to last a year. See the section of my reply to Melanie regarding PLASTIC.
While I was out earlier today I stoped at a GoodWill Store and found the kids NEXT ride “Barbie” QuadRider,
( Almost Brand NEW, No battery charger, no big deal. ) $10.00 (USD) amazing what people here “throw out”.
YEA “Barbie”(purple, pink & white) a few cans of spray paint will take care of THAT foolishness. 8-)
TWO 12 Volt motors on this thing, one on each rear wheel.
Compared to the GO Kart it’s a MONSTROUSLY large thing.
Neighborhood kids on foot and small animals will need to LOOK OUT ! ! !

Mel,
“If I was a three-year-old, I'd want to experience the joys of burning rubber from a standing start...”
Yea me too, but that’s real BAD on the PLASTIC Gearbox, as a matter of fact except for the motor, batteries,
axels and a few bits for steering linkage, the WHOLE DARN THING is plastic, Even the hollow wheels.
I’m glad I’m NOT the one who paid close to $200.00 USD retail for it. Someone lost the original battery
charger and chucked it into the Salvation Army donation box. I paid $8.00 for the thing.

If he were MY kid instead of my Sister’s he would have been real bored with this thing by three years
old because I would have started him on it at 6 months, 8 months at the outside.
WE DON’T NEED NO STINKING STROLLER ! ! ! 8-)
He would be racing GAS (Petrol) powered Go-Carts by NOW.

“Why bother with a PIC with the associated problems of Power Supply and Motor noise etc etc?”
Why bother with a PIC? I’ve got them in the parts bin collecting dust. I guess the REAL answer to that
one is my personal PicBasic experience / educ-tainment, (education + entrtainment) something I want to
have the experience of “under my belt / in my bag of tricks”.

“Just a time-delay relay that enables operation of the turbo button a few seconds after power has been applied.”
The kid needs to learn the difference in speeds first hand, I believe he already has some concept of the fact that he
can’t drive “Flat Out / Wide Open” all the time from he and his Dad playing with slotcars & NASCAR Videogames.

Although I have NO doubt that this thing will spend 90% or more of it’s running time in 12 volt
“Turbo Mode” If a time delay relay is used then there is no driver control over which speed he is going.
Also if you look at the schematic notes I posted the circuit as it stands right now has a “Parental Override”,
a 12 Volt lockout, probably nothing more than a key switch scavenged from an OLD PC Case, wired in series
with the “Turbo” button in the event his parents feel the 12 Volts is too fast for the kid to have access to from the beginning.

I hope you were thinking something along the lines of a NE555 as a timer for that Time Delay Relay,
I haven’t looked HARD, but when I look at Digikey those things are in the $100.00 and up range

This is a LOW BUDGET project,
( Prices listed in USD)
Vehicle = $08.00 Salavtion Army Store
Batteries = $05.00 (each) 2 x 12 Volt 12 Ah local Electronics Surplus Store
PIC = $02.00 Had on hand in the parts bins
Relays = $??.?? Had on hand from YEARS ago when local parts retailer closed
Car Wash = $01.75 DIY Carwash High Pressure stuff, had to blast off the cobwebs & crud
Battery Charger = $??.?? Had a box of power supplies & high current wall warts on hand.
Wire & Switches = $??.?? Had on hand 10 & 12 AWG wire and switches left over from another project

Look on the kids face when he’s ripping down the driveway and finds the Turbo, = PRICELESS ! ! !

My Brother in Law and I have TALKED about adding RC Controls to one of the full sized
Power Wheels JEEP and sticking the kid in that so we can steer him where we want him to
go instead of where he wants to go. Don’t know if that will ever happen but I’m keeping my
eyes open for a free or cheap JEEP in good condition.

[Melanie]

When I meant a Time-Delay Relay on the turbo switch, I meant that the Relay contacts were is SERIES with the switch and not in parallel with it. i.e., until the Relay threw, the turbo switch was out of circuit. Only AFTER the Relay closed, only then the turbo switch could be pressed if desired.

This way, the Time-Delay Relay is simply connected across the Motor, so when power is applied to the motor, the Relay then times and then after a preset time period closes it's contact enabling the turbo button if so desired. If you take power off the motor, the Relay drops out ready for a new timing cycle.

A couple of transistors, a Capacitor and a splattering of Resistors and you've got your circuit for about $1, no PIC, no software, and pretty much supply voltage independant with no worries about having to generate a clean 5v supply for the PIC.

[Mike_Lynch]

Melanie,

Thanks for explaining what you meant. My first reaction was to ask for a schematic,
but I want to stir some brain cells and actually THINK about what it is you are describing.
(Amazingly Sad how rusty I am on this stuff these days, if you don’t use it you LOSE it.)
I’ll have to sit down with pen & paper to see what I come up with before I come BEGGING
and have to bother you for a schematic. 8-)

Thanks
Mike_L

[Archangel]

When my Daughter was about that age I bought her a Suzuki JR50 motorcycle which she rode exactly once. Too much power and she bailed off never to ride again. So here's a suggestion: install a 1/4 inch headphone jack on the rear of this vehicle, break the power connection and wire it through the jack. the plug that mates gets a string attached to Dad or Grandpa. short the inner to the outer conductor of the plug. when it's plugged in he has power, if it gets away from him, the plug pulls out and it stops. You could get creative and use a shorting type jack so instead of stopping it switches to low power. I doubt
Dale Earnhart JR's. first ride was souped up very much.

RULE 1, SAFETY FIRST (Especially with kids)
RULE 2. Go back to rule 1

[Acetronics2]

Hi, Joe

I see something ... a DC motor Torque is a major function of the drawn current ...

soooo, limiting the Max current is a fair way to achieve your goal.

Now how ??? ... Mosfets have an internal ON resistance ... so, using PWM, just measure the D to S voltage, during the ON state ( 100% will also work ...), exactly as with a shunt ...
A simple comparator will short the gate voltage to ground if overcurrent... and allow to easily trim the limit.

That's what used on Power speed regulators for Electric models ...

now, you DO NOT have PWM aboard ... so, just sample D/S Voltage , say @ 500 hz to 3 KHz ( match to the motor ). Limitation will then be smooth enough.

Using a PIC to slowly automatically increase the PWM rate will add the soft start function ... and you've what you want

AND the MOTOR is SAFELY DRIVEN ...

Alain

[Mike_Lynch]

Well, I dropped a 12V 12Ah Gel Cell into that “Barbie” QuadRider thing.
While testing for broken wires, switches or stripped gearboxes I precariously
balanced about 170 lbs. (ME) on the seat and pressed the switch.
The thing MOVED, only a couple of feet, didn’t want to over tax things.

(So if you are in need of motor / gearbox with a TON of torque, you now know where to look.)

If Gas (Petrol) prices keep going up (* See note below), I may park the van
and drive this thing to work. I’ll just have to leave a WHOLE LOT EARLIER ! 8-)

Gas Prices: Yea I know people in other parts of the world have it a lot worse than
we do in the states, my Gas costs 2.75 ~ 3.00 a Gallon I just have to complain a little
because I remember when I started driving (back when you had to wait for a Dinosaur
to die and decay before you could Fill Up) Gas was 0.57 a Gallon.

[Melanie]

Stop moaning! I fueled this morning and the UK price works out at about US$7.90 a gallon (based on 94p/litre for unleaded and US$1.85 to the pound Sterling). It's dropped a little, beginning of last week it was closer to $8.40.

Actually, since we've got an international audience, let's have a little survey, can we get a few folks posting what today's price for unleaded and diesel is in your country?

[Mike_Lynch]

US$7.90 to $8.40a gallon, OUCH !

But doesn’t YOUR daily driver require HIGH OCTANE AVIATION Fuel ?


Mel's erand runner, Daily Driver

[sayzer]

Stop moaning! I fueled this morning and the UK price works out at about US$7.90 a gallon (based on 94p/litre for unleaded and US$1.85 to the pound Sterling). It's dropped a little, beginning of last week it was closer to $8.40.

Actually, since we've got an international audience, let's have a little survey, can we get a few folks posting what today's price for unleaded and diesel is in your country?

Here:
91 Octane Unleaded : US$2.60/liter (101 Octane US$2.70/liter)
Diesel : US$1.38/liter


What about BigMac prices?

[Acetronics2]

In France , these days, 88 unleaded is ~ 1.65 US$ and 98 UL 1.7 US$

Diesel ??? who's that's for ???

I thought Big Macs were obtained from raw oil ... as Coca-Cola !!!

Sure, their prices raise ...

Alain

[f_lez]

I've seen these gas price threads before, and while interesting, its useless to compare them like for like on 1 item, so what about a TOTAL in $ for the following....

I suggest the following items for this comparison and submit my accurate guestimated figures...


$08.50 1 gallon of gas (100P PER GAL)

$11.00 1 bigmac meal

$02.30 3 ltrs of economy store ice cream (walmart asda, 39p per ltr)

$06.94 1 'nice' 14 inch deep pan (supermarket) (walmart asda 3.68)

$88.00 200gb HD (7200 8mb samsung or equiv) (svp 47ukp)

$10.00 A cheap pair of jeans.... (walmart asda, 5)

Total for this is $126.74

Now what can I expect for a an average joe job like a bus driver?

about 200 in your pocket a week or $370

I dont expect others to be able to guess their housing costs etc, but I spend about $25 a week on fuel costs (ie heating+electricity) and an average rent is about $130 for a small house in the outer green bits, or for a small room in a large city.

[Chard]

Stop moaning! I fueled this morning and the UK price works out at about US$7.90 a gallon (based on 94p/litre for unleaded and US$1.85 to the pound Sterling). It's dropped a little, beginning of last week it was closer to $8.40.

Actually, since we've got an international audience, let's have a little survey, can we get a few folks posting what today's price for unleaded and diesel is in your country?

Kingston, Ontario

Regular Gas US$ .85.6 - .90.2 per litre
Diesel US$ .83.8 - .88.3 per litre