Used to be the standard trick question in the old british driving test.

"It has been snowing heavily and all the marking on the road are covered in snow and the signs are also obscured.
You are approaching a road junction and all you can see is the snow covered sign on a pole. How do you know if it is a 'halt' or 'give way'? "
(In the UK we used to call them halt not stop signs.)

Incidentally to say "stop anyway" was not acceptable.

Here in the US, the answer would be "different shapes." I've never seen road signs in the UK, though.

 

The digital pot won't work with a negative voltage, but I suspect you reversed the meter leads.

But to keep the same reference (the wiper) you would need to switch the leads.

To operate the DPot all i need is a falling edge of the 555 pulse. The voltae on the RH, RL, and RW of the pot is not a factor...it's no different than the original.

I think!

 

A FINAL word on the secondary conversation, Safety. Then I'd prefer using the general thread for this conversation.

Responsibility is learned, not forced. How human are we if we are forced by our mothers to wear a helmet and padded cloths to go run and play in our back yards. We can lecture all we want to our kids that it is not safe to smoke, ride a bike no-handed...etc but rest assured, when your not looking, their gonna try it. Why? Because all the statistics in the world will not substitute for the experience of doing. Sometimes we must close our eyes and let our kids fall so that they can process the information and make their own conclusions. If and old man makes such decisions against all statistical odds. He continues to smoke or eat fried foods despite his doctors warnings. Enough said.

If you have any suggestions on how to make the circuit work and work safely as well, then I welcome your comments here and will be appreciative, but I no longer need mommies lectures in this thread please.

Thanks all.

 

Used to be the standard trick question in the old british driving test.

"It has been snowing heavily and all the marking on the road are covered in snow and the signs are also obscured.
You are approaching a road junction and all you can see is the snow covered sign on a pole. How do you know if it is a 'halt' or 'give way'? "
(In the UK we used to call them halt not stop signs.)

Incidentally to say "stop anyway" was not acceptable.

Stopping and starting out, and making radical changes in direction are the most dangerous things while driving on snow and ice. Best to keep a slow, constant speed. Stopping in thick layer of snow, often leads to getting stuck...

 

not sure the specific DPot I chose will work for m applicaion. Was eying the several from MAXIM Dallas. MAX5529, MAX5474, DS1809. These may work netter for my application.

 

What about replacing your annoying rheostat with a joystick instead?

There are commercial/industrial/medical grade joystics available that will have a long lifespan. I wouldn't trust some cheap junk, as it could leave you stranded or worse.

At any rate, whatever you wind up using, you will need some kind of "panic button" that when you whack it, you come to a safe, rapid stop - just in case something breaks.

 

Responsibility is learned, not forced.

The trouble is that have to hold the rheostat arm at a specific position to maintain a constant speed, if I let go I come to a screeching halt.

It's funny how I searched for a scooter that had a particular ground clearance so that I could get up bumps and ride on the lawn, but the then the scooter mfg. put the safety tip wheels on the back so I couldn't pop wheelies,...

It's like the infamous STOP sign. Does it make it any safer to stop at one if there is not car, pedestrian, or and other living creature withing a mile from the intersection.

Let's see:

1) You want to defeat the deadman switch on a motorized scooter so you can indulge in dangerous activities, including perhaps, doing wheelies on neighbors' yards.

2) You don't think stop signs should apply to you, if you don't see any traffic.

While one cannot force responsibility, as you observe, you obviously haven't learned much either.

It is not a question of mothering you. It is a question of protecting the community from individuals like you who have failed to learn responsibility by observation and common sense. I suspect when the inevitable accident occurs, you will offer as an excuse for accepting full responsibility, "I didn't know that would happen."

I don't think helping you design such a unsafe device for a motor scooter is much different than helping someone design a cell phone jammer. Both are dumb ideas.

John

 

What about replacing your annoying rheostat with a joystick instead?

There are commercial/industrial/medical grade joysticks available that will have a long lifespan. I wouldn't trust some cheap junk, as it could leave you stranded or worse.

At any rate, whatever you wind up using, you will need some kind of "panic button" that when you whack it, you come to a safe, rapid stop - just in case something breaks.

I'm not sure the Joystick would do it. The current rheostat is nothing more than a horizontal bidirectional joystick.

I was intending to have a forward/reverse/and "Panic Stop button" and the 1/4 inch stereo plug-like key cuts power completely as well.

I think what I still need now is a was to flip a logic state and latch it at and at the same time start the 555 pulse generator. In other words flipping the state to High on one pin and starting the 555 to another pin to go forward. Pressing a second button would flip the logic state to low on the first pin and start the 555 pulse to go in reverse.

 

Let's see:

1) You want to defeat the deadman switch on a motorized scooter so you can indulge in dangerous activities, including perhaps, doing wheelies on neighbors' yards.

2) You don't think stop signs should apply to you, if you don't see any traffic.

While one cannot force responsibility, as you observe, you obviously haven't learned much either.

It is not a question of mothering you. It is a question of protecting the community from individuals like you who have failed to learn responsibility by observation and common sense. I suspect when the inevitable accident occurs, you will offer as an excuse for accepting full responsibility, "I didn't know that would happen."

I don't think helping you design such a unsafe device for a motor scooter is much different than helping someone design a cell phone jammer. Both are dumb ideas.

John

John, Thanks for your input. Although I have much to refute here I shall stick with the simple No Comment. You could have spent this time helping me build safety into my design, but you chose lecturing instead.
I suppose Sir Edmond Hillary and Columbus had to get their earful as well.

 

I guess you already locked into this singular idea for your suicide machine, but thought of another method, which might be cheaper (maybe free), more reliable, and likely take only a few minutes. Got the idea from an R/C transmitter modification for my Helicopter. You remove the return springs, so the joysticks don't self-center, and a small piece of tubing is placed on the metal strip that ratchets. Didn't do it, not much of a pilot, so not important yet. But make sense that the controls move smoothly, and only change when you actually move the sticks.

You are basically looking for a cruise control, why not modify the control handle, so it stays in the position you place it. Might be able to add a lever that locks the position, when released you would have normal operation.

Have you consider the dead-man might serve another purpose, like maybe you should be stopped, before changing direction? Might be a little rough on the electronics otherwise.

Guessing you aren't dependent on this scooter for getting around, it's just for fun and excitement. So if something burns up, or you crash it, you'll still be able to walk away.

Really shouldn't be so negative about the dead-man, it's been very useful for me at work. I drive like a maniac, always in a hurry. Normally, you would use reverse to slow down, the dead-man saves time. Our pallet jacks probably do considerably better than 5 mph though.

Anyway, hope you enjoy your scooter as much, when you no longer have a choice about using one. Perhaps you should start on your future wheelchair...

 

I guess you already locked into this singular idea for your suicide machine, but thought of another method, which might be cheaper (maybe free), more reliable, and likely take only a few minutes. Got the idea from an R/C transmitter modification for my Helicopter. You remove the return springs, so the joysticks don't self-center, and a small piece of tubing is placed on the metal strip that ratchets. Didn't do it, not much of a pilot, so not important yet. But make sense that the controls move smoothly, and only change when you actually move the sticks.

It does sound interesting, but without a quick way to "self-center" I'd be in motion, forwards or backwards all the time, sounds like bumper cars!

Have you consider the dead-man might serve another purpose, like maybe you should be stopped, before changing direction? Might be a little rough on the electronics otherwise.

Actually, the Forward and reverse buttons would do that, reverse would not automatically throw me into reverse, but decrement the pot. I will have the "Stop button" which can get me to center pot position, then reverse to go backwards. The forward/reverse buttons would actually be Increment/Decrement.

Guessing you aren't dependent on this scooter for getting around, it's just for fun and excitement. So if something burns up, or you crash it, you'll still be able to walk away.

A little humor here, I like the touch!

 

No lectures from this end, but I'll suggest that the KISS principle applies

Seems to me that the whole digital pot thing is escalating the complexity considerably. The more components you have in a system, the more likely you are to have a failure. If you aren't dependent upon this scooter for mobility, then at the least a failure will be an inconvenience. If you are, it will be at least a royal PITA, because you may find yourself stranded somewhere.

At least you have a plan for a "panic button". If you can get around under your own power, that should be enough. But if you're dependent on this scooter for mobility, I suggest that you need some kind of redundancy, or a "Plan B", so that you minimize your chances of getting stranded.

While having buttons to press to increase/decrease speed a step at a time might be logical, it's not terribly intuitive. Also, having a number of switches increases the possibilities for failures. Electromechanical devices have a really annoying habit of going intermittent or breaking at most inopportune times.

 

No lectures from this end, but I'll suggest that the KISS principle applies

Seems to me that the whole digital pot thing is escalating the complexity considerably. The more components you have in a system, the more likely you are to have a failure. If you aren't dependent upon this scooter for mobility, then at the least a failure will be an inconvenience. If you are, it will be at least a royal PITA, because you may find yourself stranded somewhere.

At least you have a plan for a "panic button". If you can get around under your own power, that should be enough. But if you're dependent on this scooter for mobility, I suggest that you need some kind of redundancy, or a "Plan B", so that you minimize your chances of getting stranded.

While having buttons to press to increase/decrease speed a step at a time might be logical, it's not terribly intuitive. Also, having a number of switches increases the possibilities for failures. Electromechanical devices have a really annoying habit of going intermittent or breaking at most inopportune times.

Points well taken. Redundancy will be Plan "B". This will consist of the original deadmans Pot in place, but with its interface disconnected and the armature removed. Then the armature along with a hex wrench and Phillips screwdriver I can unplug the digital interface and plug back the mechanical interface.

And while not completely dependent upon the scooter for mobility I would be a PITA, or should I say Pain In The Legs to have to get back from somewhere, let alone retrieve the scooter.

 

Well after some browsing about with datasheets for Digital Pots I came up with one that seems to follow the KISS principle quite well. I was in the middle of calculating duty cycles for 555's adding Logic to change the state of a CS pin, yada yada... But the Digital Pot I found today allows me to eliminate that all together. The MAXIM1809

http://www.alldatasheet.com/datasheet-pdf/pdf/58539/DALLAS/DS1809.html

 

You should notice the fact that the pot is non-volatile, so if you from full throttle because of the dead-man´s switch, then immediately after you push it back on you will start with full throttle again.

 

You should notice the fact that the pot is non-volatile, so if you from full throttle because of the dead-man´s switch, then immediately after you push it back on you will start with full throttle again.

If I understand correctly, what you are saying is that once you power down the pot and then power-up again it will start at the last position used.

I believe this is the case when you tie pin 3 (STR) to Vcc via a shottky diode and to ground via a cap. I believe this is bypassed when tyeing Pin 3 directly to ground as stated below.... if I am interpreting it correctly.

COMMAND-INITIATED WIPER STORAGE
The DS1809 will also support a command-initiated wiper storage operation during powered conditions. For command initiated storage the STR pin should be held in a low state on power-up; otherwise the part will assume an autostore configuration. A low-to-high pulse lasting at least 1 µs on the STR input will cause the DS1809 to initiate the storage of the current wiper position into EEPROM when Vcc is present. For applications not requiring or using the nonvolatile memory feature of the DS1809, it is recommended that the STR input be connected to GND.

Thus, If I read correctly and long at pin 3 (STR) is low, no wiper position will be written into storage. Please correct me if I am wrong!

 

Sorry you are right, I didn´t notice that.

 

I started the teacup tempest about the deadman switch, but let me pose a question:
How many of you have a car with a deadman switch on the cruise control?

 

I started the teacup tempest about the deadman switch, but let me pose a question:
How many of you have a car with a deadman switch on the cruise control?

Never really used the cruise control, just messed with until I figured out how to use it. Seems to disengage when you hit the brake or accelerator pedals. Bunch of other buttons and crap I never deciphered. Don't see it as being real useful in traffic.

 

I think cruise control is more usefull on an empty highway when you use it as speed limiter so you can concentrate more on driving than watching your speed.
I never used it, but I always thought it disengages when you release the accelerator. Is that right?