Cruise control mod?

Guest
So I have this aftermarket cruise control in my car that uses the
speed signal from the car to set the speed. It does not use magnets on
the driveshaft. The cruise control only starts working above 35 mph.
Every cruise control I have ever used, factory or aftermarket, only
worked from about 35mph and above. But I do a lot of driving below 35
mph and want to use the cruise control for it. So I'm hoping that if I
measure the signal from the car with an oscilloscope it wil show
either a chain of pulses or a voltage that changes with the speed. I
looked online and found a couple frequency doubling circuits that look
like they would work. I'm sure that the extra pulses the circuit would
make must be evenly spaced between the pulses from the car for my
scheme to work. And at least one of the circuits I found appears to do
just that. If it is a rising voltage that I need to modify I'm not
sure how I would do that. What if the rise with speed isn't linear?
Anyway,any thoughts or advice? Any circuits that would work? Maybe a
chip to do all the work?
Thanks,
Eric
 
etpm@whidbey.com wrote:

So I have this aftermarket cruise control in my car that uses the
speed signal from the car to set the speed. It does not use magnets on
the driveshaft. The cruise control only starts working above 35 mph.
Every cruise control I have ever used, factory or aftermarket, only
worked from about 35mph and above. But I do a lot of driving below 35
mph and want to use the cruise control for it. So I'm hoping that if I
measure the signal from the car with an oscilloscope it wil show
either a chain of pulses or a voltage that changes with the speed. I
looked online and found a couple frequency doubling circuits that look
like they would work. I'm sure that the extra pulses the circuit would
make must be evenly spaced between the pulses from the car for my
scheme to work. And at least one of the circuits I found appears to do
just that. If it is a rising voltage that I need to modify I'm not
sure how I would do that. What if the rise with speed isn't linear?
Anyway,any thoughts or advice? Any circuits that would work? Maybe a
chip to do all the work?
Thanks,
Eric
Click to expand...
It makes perfect sense to have it not operate until that speed or there
abouts.

Or is there some ulterior motive at work?


Jamie
 
On Wed, 26 Jun 2013 17:09:18 -0700, etpm@whidbey.com wrote:

So I have this aftermarket cruise control in my car that uses the
speed signal from the car to set the speed. It does not use magnets on
the driveshaft. The cruise control only starts working above 35 mph.
Every cruise control I have ever used, factory or aftermarket, only
worked from about 35mph and above. But I do a lot of driving below 35
mph and want to use the cruise control for it. So I'm hoping that if I
measure the signal from the car with an oscilloscope it wil show
either a chain of pulses or a voltage that changes with the speed. I
looked online and found a couple frequency doubling circuits that look
like they would work. I'm sure that the extra pulses the circuit would
make must be evenly spaced between the pulses from the car for my
scheme to work. And at least one of the circuits I found appears to do
just that. If it is a rising voltage that I need to modify I'm not
sure how I would do that. What if the rise with speed isn't linear?
Anyway,any thoughts or advice? Any circuits that would work? Maybe a
chip to do all the work?
Thanks,
Eric
Click to expand...
It's non-linear... dphi/dt. Count the pulse rate, not the average
amplitude.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
On Wed, 26 Jun 2013 20:39:42 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

etpm@whidbey.com wrote:

So I have this aftermarket cruise control in my car that uses the
speed signal from the car to set the speed. It does not use magnets on
the driveshaft. The cruise control only starts working above 35 mph.
Every cruise control I have ever used, factory or aftermarket, only
worked from about 35mph and above. But I do a lot of driving below 35
mph and want to use the cruise control for it. So I'm hoping that if I
measure the signal from the car with an oscilloscope it wil show
either a chain of pulses or a voltage that changes with the speed. I
looked online and found a couple frequency doubling circuits that look
like they would work. I'm sure that the extra pulses the circuit would
make must be evenly spaced between the pulses from the car for my
scheme to work. And at least one of the circuits I found appears to do
just that. If it is a rising voltage that I need to modify I'm not
sure how I would do that. What if the rise with speed isn't linear?
Anyway,any thoughts or advice? Any circuits that would work? Maybe a
chip to do all the work?
Thanks,
Eric

It makes perfect sense to have it not operate until that speed or there
abouts.

Or is there some ulterior motive at work?


Jamie
I drive a lot of roads here on the island at about 25 mph. I would
Click to expand...
like to use cruise control. That's the only motive. So any help?
Eric
 
On Wed, 26 Jun 2013 17:09:18 -0700, etpm wrote:

So I have this aftermarket cruise control in my car that uses the speed
signal from the car to set the speed. It does not use magnets on the
driveshaft. The cruise control only starts working above 35 mph. Every
cruise control I have ever used, factory or aftermarket, only worked
from about 35mph and above. But I do a lot of driving below 35 mph and
want to use the cruise control for it. So I'm hoping that if I measure
the signal from the car with an oscilloscope it wil show either a chain
of pulses or a voltage that changes with the speed. I looked online and
found a couple frequency doubling circuits that look like they would
work. I'm sure that the extra pulses the circuit would make must be
evenly spaced between the pulses from the car for my scheme to work. And
at least one of the circuits I found appears to do just that. If it is a
rising voltage that I need to modify I'm not sure how I would do that.
What if the rise with speed isn't linear? Anyway,any thoughts or advice?
Any circuits that would work? Maybe a chip to do all the work?
Thanks,
Eric
Click to expand...
I'm sure I answered this, yet I can't see anything.

Look for a PLL frequency doubling circuit. Expect that the PLL may add
enough delay to mess up the system response. Try, and see.

If you really want to get into it, you could always keep the servo
mechanism and put in your own electronics.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
 
On Wed, 26 Jun 2013 17:09:18 -0700, etpm@whidbey.com wrote:

So I have this aftermarket cruise control in my car that uses the
speed signal from the car to set the speed. It does not use magnets on
the driveshaft. The cruise control only starts working above 35 mph.
Every cruise control I have ever used, factory or aftermarket, only
worked from about 35mph and above. But I do a lot of driving below 35
mph and want to use the cruise control for it. So I'm hoping that if I
measure the signal from the car with an oscilloscope it wil show
either a chain of pulses or a voltage that changes with the speed. I
looked online and found a couple frequency doubling circuits that look
like they would work. I'm sure that the extra pulses the circuit would
make must be evenly spaced between the pulses from the car for my
scheme to work. And at least one of the circuits I found appears to do
just that. If it is a rising voltage that I need to modify I'm not
sure how I would do that. What if the rise with speed isn't linear?
Anyway,any thoughts or advice? Any circuits that would work? Maybe a
chip to do all the work?
Thanks,
Eric
Click to expand...
I've had success, both over :)-) and under range, by initially setting
a mid-value, then using either the Accel or Coast buttons to get the
speed I want...

For instance, my Q45 won't set above 75, but I can Accel it up to my
desired 100 >:-}

BTW, most speed sensors are wheel-based.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
Is it an option to use engine rpm rather than the speedometer pickup as the
controlling signal? Possibly better suited for lower speeds.
30 to 35 mph is where the torque converters usually lock up so using the
speedo pickup presents hunting problems at lower speeds.

<etpm@whidbey.com> wrote in message
news:5k0ns8td6e8g33ne7t1ehjtjvql4tledah@4ax.com...
So I have this aftermarket cruise control in my car that uses the
speed signal from the car to set the speed. It does not use magnets on
the driveshaft. The cruise control only starts working above 35 mph.
Every cruise control I have ever used, factory or aftermarket, only
worked from about 35mph and above. But I do a lot of driving below 35
mph and want to use the cruise control for it. So I'm hoping that if I
measure the signal from the car with an oscilloscope it wil show
either a chain of pulses or a voltage that changes with the speed. I
looked online and found a couple frequency doubling circuits that look
like they would work. I'm sure that the extra pulses the circuit would
make must be evenly spaced between the pulses from the car for my
scheme to work. And at least one of the circuits I found appears to do
just that. If it is a rising voltage that I need to modify I'm not
sure how I would do that. What if the rise with speed isn't linear?
Anyway,any thoughts or advice? Any circuits that would work? Maybe a
chip to do all the work?
Thanks,
Eric
Click to expand...
 
Oppie expressed precisely :
See BOTTOM Posting
Is it an option to use engine rpm rather than the speedometer pickup as the
controlling signal? Possibly better suited for lower speeds.
30 to 35 mph is where the torque converters usually lock up so using the
speedo pickup presents hunting problems at lower speeds.

etpm@whidbey.com> wrote in message
news:5k0ns8td6e8g33ne7t1ehjtjvql4tledah@4ax.com...
So I have this aftermarket cruise control in my car that uses the
speed signal from the car to set the speed. It does not use magnets on
the driveshaft. The cruise control only starts working above 35 mph.
Every cruise control I have ever used, factory or aftermarket, only
worked from about 35mph and above. But I do a lot of driving below 35
mph and want to use the cruise control for it. So I'm hoping that if I
measure the signal from the car with an oscilloscope it wil show
either a chain of pulses or a voltage that changes with the speed. I
looked online and found a couple frequency doubling circuits that look
like they would work. I'm sure that the extra pulses the circuit would
make must be evenly spaced between the pulses from the car for my
scheme to work. And at least one of the circuits I found appears to do
just that. If it is a rising voltage that I need to modify I'm not
sure how I would do that. What if the rise with speed isn't linear?
Anyway,any thoughts or advice? Any circuits that would work? Maybe a
chip to do all the work?
Thanks,
Eric
Click to expand...
If you use engine rpm then you have to take the gear selection into
account. lol

--
John G
 
"John G" <greentest@ozemail.com.au> wrote in message
news:BpOdnUCzEa5cw37MnZ2dnUVZ_r2dnZ2d@westnet.com.au...
Oppie expressed precisely :
See BOTTOM Posting
Is it an option to use engine rpm rather than the speedometer pickup as
the controlling signal? Possibly better suited for lower speeds.
30 to 35 mph is where the torque converters usually lock up so using the
speedo pickup presents hunting problems at lower speeds.

etpm@whidbey.com> wrote in message
news:5k0ns8td6e8g33ne7t1ehjtjvql4tledah@4ax.com...
So I have this aftermarket cruise control in my car that uses the
speed signal from the car to set the speed. It does not use magnets on
the driveshaft. The cruise control only starts working above 35 mph.
Every cruise control I have ever used, factory or aftermarket, only
worked from about 35mph and above. But I do a lot of driving below 35
mph and want to use the cruise control for it. So I'm hoping that if I
measure the signal from the car with an oscilloscope it wil show
either a chain of pulses or a voltage that changes with the speed. I
looked online and found a couple frequency doubling circuits that look
like they would work. I'm sure that the extra pulses the circuit would
make must be evenly spaced between the pulses from the car for my
scheme to work. And at least one of the circuits I found appears to do
just that. If it is a rising voltage that I need to modify I'm not
sure how I would do that. What if the rise with speed isn't linear?
Anyway,any thoughts or advice? Any circuits that would work? Maybe a
chip to do all the work?
Thanks,
Eric

If you use engine rpm then you have to take the gear selection into
account. lol
Click to expand...
There is that...
One can always (if so equipped) put the transmission into manual to hold a
particular gear.

I had a car with a speed control problem. Never quite fixed it so just
learned to live with it...
2001 Saturn LW300 (3 liter, 24 valve V6, 4 speed "rocket") - going along on
level ground with the speed control set, when approaching a hill and speed
begins to fall off, it would downshift *two* gears and red line the tach!
Very unnerving when automatic systems do that. Saturn "fixed it" briefly but
it happened again about six months later. Finally just turned off the speed
control when on anything but flat road...
 
On Sun, 14 Jul 2013 21:44:11 -0400, "Oppie" <Oppie@127.0.0.1> wrote:

Is it an option to use engine rpm rather than the speedometer pickup as the
controlling signal? Possibly better suited for lower speeds.
30 to 35 mph is where the torque converters usually lock up so using the
speedo pickup presents hunting problems at lower speeds.
I don't know if I can use engine RPM. But since the car has an
Click to expand...
automatic transmission I can see the RPM approach causing all sorts of
hunting problems if the transmission shifts. I suppose I could put the
transmission selector in second for low speed but that would prevent
using the cruise control for anything but low speeds. Also, since the
transmission doesn't hunt when I use the gas pedal to hold it at 25 I
don't see how it would with a cxruise control. Next time I drive the
car I will pay attention to what speed the transmission decides to
shift.
Eric


etpm@whidbey.com> wrote in message
news:5k0ns8td6e8g33ne7t1ehjtjvql4tledah@4ax.com...
So I have this aftermarket cruise control in my car that uses the
speed signal from the car to set the speed. It does not use magnets on
the driveshaft. The cruise control only starts working above 35 mph.
Every cruise control I have ever used, factory or aftermarket, only
worked from about 35mph and above. But I do a lot of driving below 35
mph and want to use the cruise control for it. So I'm hoping that if I
measure the signal from the car with an oscilloscope it wil show
either a chain of pulses or a voltage that changes with the speed. I
looked online and found a couple frequency doubling circuits that look
like they would work. I'm sure that the extra pulses the circuit would
make must be evenly spaced between the pulses from the car for my
scheme to work. And at least one of the circuits I found appears to do
just that. If it is a rising voltage that I need to modify I'm not
sure how I would do that. What if the rise with speed isn't linear?
Anyway,any thoughts or advice? Any circuits that would work? Maybe a
chip to do all the work?
Thanks,
Eric
Click to expand...
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top