Small 12v Auto circuit for on/off switch – Newbie help

Hi All,

Not sure if this is even possible, I have a press button switch with LED light for a car, IE press the button and it completes a circuit (continuity tested) and led light on , basicall it has four wires that I need to use

2 pairs for the in and out feed
2 pairs for the LED circuit

I am looking for a small circiut that will act as a on/off switch and power the LED,

Hope this makes sense,

press the button in and it turns a 12v feed off ,cutting the 12v output and switching on the LED light,

Press the button again and it swtiches off the LED light and then allows the 12v output to pass through again,

it also needs to auto reset once all power has been switched off ready to start again ?

Draw a schematic and post it. No your description make no real sense.

as what i understand from your description you want to have an indicator that power has been cutoff to the device that your 12v source is feeding. what i don't understand is why the reset function bcoz once you turn off the LED, power is again connected to whatever device is powered up. unless you want another function performed when the LED is turned off and power is to be diverted to another load.

Hope this will help ? sorry its very basic

What I get from Mark's description is that he wants a press-on-press-off switch with a light that comes on when the switch has cut the power (perhaps so the switch can be found in the dark). When the 12V supply, that the switch is controlling, goes to zero volts (i.e. shuts down), the switch needs to reset to it's open state (I have this issue with a couple of my multimeters. They have push-on-puch-off mechanical switches but they also have an auto-turn-off "feature". When the meter turns itself off, I have to cycle the mechanical switch twice to turn the meter back on). Mark doesn't want to have to do that. He wants the switch to automatically return to the "off" state after the 12V supply is cycled.

Mark: did I get that right?

Kind of,

I've retro fitted OEM parking senors on my car, but I wanted to add a switch to the front sensors. I've purchased switch No 7 http://opeloem.com/vauxhall/insignia...d_sensors.html which is part 13315847 on this link,

But the button isnt a standard on/off switch, it must work through the cars PDC kit if fitted att he factory,. I've tested each cable using a continuity test and found two cables that give a tone when testing , IE the feed in and out. ?

But, its not a standard on/off button, if you press the button in , it only completes the circuit while you hold in the button, , hope this makes sense , this needs to go off to a switching relay that keeps the feed on or off until the next button press ?

On top of that, when the feed is switched off I need the led on the button to light up to say the 12v has been swithced off ?

does that make more sense ? . the only reason for the auto reset was that the 12v feed cuts off at 6mph. did you see the wire diagram above ?

Look if you can't draw a schematic you CAN'T design it. The schematic simply represent your idea in your head and it communicates to other like minds.

You know the hallway light switch? You can turn the lights on or off from either switch ( one switch at each end of the hallway). How does that work, draw a schematic. This is the concept here.

As for an LED indicating the switched position, that is too easy and I won't even describe it.

DRAW A SCHEMATIC, even a conceptual sudo-schematic, because the word are just too confusing.

hanks for you help buddy , if I wanted a rude response I would have asked for one, may be I came to the wrong please looking for help ?

for those that tried to help, may thanks !

Sorry you did provide a sudo schematic.My mistake.

What you describe is known as a holding circuit How does that work. Here is what you have:

2 - SPST push button switches {single pole single throw} One needs to be normally on the other normally off. Or 2 SPDT {single pole, double throw}

1 - 12 Volt relay DPDT {double pole double throw}

One bottom energies the relay across the 12V. One set of contacts on the relay, normally off is in parallel with the push button contacts. So when you push the button, relay turns on, shunts the push button contacts, and when the push button is released the relay stays on, circuit is energized.

The 2nd push button is in series with the 1st push button and relay coil to complete the circuit. This push button is normally on. When you push this button, it breaks the relay coil circuit and the relay turns off.

The relay's second set of contacts would control your external circuit, what ever that is.

So the relay contacts, one set controls the holding circuit and LED ststus indicators. The other set of contacts control the external load you want to control & any LED ststus indictors.

This is known as a holding circuit, or set & reset.

This can be done with transistors as well. Also this can be done with two toggle switches (DPDT), two wires in, three between the switches, and two wires out.

I don't have a scanner at home so I can't send you a schematic. If it can wait till then.

But this is real simple two wire system. Push to turn on (one button) push to turn off, second button. If you want a single button to do both, that's possible too using a toggle flip flop.

Ok so after looking at your requirements you need one button to do two things. Ok so this involves a toggle circuit. Push button 1st time, function goes from state A to state B. Push the button again and circuit goes from state B back to state A.

Here is a URL for simple toggle circuits that you are someone else will need t build. These are real simple and common components but will allow you to do what you need. I have included two of the circuits that are most suitable I believe for your application. The rest which would be status indicators you can sort out as you see fit.

http://www.bowdenshobbycircuits.info/page9.htm.

ok, thanks , happy to wait and appreciate the reply with the pointers.

I have the switch already so its a single switch and led is build in, will have a hunt round for more info .

Many thanks, this is good info and should help me out, will find someone locally to make one up.

thanks again,

Mark:

The "Relay Toggle Circuit Using a 555 Timer" on "page9" should do what you want -- if the 555 reset doesn't force this circuit into the same state on every power up, then I would, instead of connecting the reset line directly to 12V, I would add a "reset delay" circuit: a resistor from Reset to +12V and a capacitor from Reset to Ground. Something like 15K for the resistor, and 0.047uF (47nF) cap.

yes the 555 would do well I believe too. good point to come up always in a predictable fashion. good point!

I have followed this discussion with some interest.
A few points that occurred to me:
1) Many folks using EEWeb will likely have "good ideas" or something perceived as relatively simple, with which they may need implementation help.
2) We have to accept (IMHO) that they may not be able to foresee design obstacles, they may not be able to draw a schematic, in fact probably do not have the tools or background to draw anything that would be useful to an EE.
3) They ask for help, often providing only very limited background info.
4) Nothing new here. An EE who chooses to help, then needs to ask all the right questions & decide whether to follow through. There is no point in getting frustrated, & no point in scolding the enquirer because they have not done this or that, or failed to adequately answer key questions.
5) If the help becomes too hard or time consuming, I suggest its best to politely say just that. Providing links for follow up can be very helpful but it's important that these links are likely to be of some use. Often they are beyond the skill level of the enquirer or are subtly "different".
6) undertaking a help request can become quite time consuming, Those patient souls who manage their help to a final solution deserve our admiration & their efforts should be appreciated by those whom they help. Generally I think this is the case.

Now exactly what is the difference between a circuit diagram & a schematic; if I may ask?

"Now exactly what is the difference between a circuit diagram & a schematic;
if I may ask?"

I am sure some will say they are essentially the same, some will point out differences. For me it is a string point in communication of ideas. I talk with EEs every day and they start taking about this or that, my comment to them, get to the point, draw me a schematic, a diagram, a flow chart. This is just a tool to convey a mental concept even if we don't speak the same language, and especially if that's the case, Chinese, Indians, Italians, the list goes on and on.

Once I looked at your diagram, noticed two functions and one button, my experience told me the best way to solve the problem. I did not follow up with all the details or hold your hand because if you are interested in electronics you have to learn by doing things your self, doing your own research, learning how to ask questions. You own that part.

As it turns out, if you are going to get a job in electronics, they won't waste much time on chit chat, they give you a pen/paper or marker/white-board and have you diagram things. They want to see how you think and solve problems so they use the universal language of schematic diagrams. These can even be just function blocks, concepts, no actual circuit values and even more so if you are describing computer code.

I certainly do understand your frustration. I have the same issue when I go to Open Source web sites to download software and try to get it to work. I ask questions to the gurus and they, well let me say I have very choice words for these gurus that I can't say here, I usually wind up going to someone and offer them money to help me get past the sticking point since I don't have 10 years to become a UNIX guru.

I hope you get your project working, it would validate your patience. Engineers hate giving up on a problem. When you do, let us know. That's one thing that seems never to happen, we never hear of success.

Earl,
I think you were responding to my observations, for that I thank you.
The schematics issue you have answered very well - I get it!

I remain of the opinion that it is too easy to expect enquirers (for help) to go off & embark on a self teaching program.
Most of us will use the internet (that's a basic expectation of everyone I suggest) but luck may initially dictate how well this serves us.
In this discussion, I responded with my observations because I felt the response to the request for help did not quite measure up to the level needed for the enquirer to either understand what was being suggested, or him him to attempt to construct a circuit (all IMHO of course).
Perhaps he may yet offer his feelings on this. I hope so.

Thank you for the info

Peter

to be honest, no it didn’t directly help as I have no idea about circuits of this type and I'm sure I'll never have the ability or more importantly the time or recourses to learn,

But , with everyone's responses and idea's has giving me the knowledge to ask the right type of questions to people that can make these types of circuits (hopefully LOL), so based on that it certainly has helped , OK it was a bit bumpy along the way

I'm always of a mind that if you don’t know yourself , someone on a forum will be able to help and be able to piece together the ramblings of someone that knows nothing, but has the idea of what he wants to do

hopefully I have found someone that has built a similar circuits and will be happy to undertake the project and it will be money well spent , as I'll never learn to do it myself ,

So, to all those have responded ,. thanks all for the assistance

Hi After looking at your diagrams I put together a circuit for you which you will need to produce a pcb for and program I can do this for you but this is a service that I charge for If you need advice please contact my via eeweb

Hope this helps

Please see attached
Mark Harrington

Just as a point of interest to you although we should not forget the principles of 555 timers and cmos logic This is now the best approach to the future of electronics

Appolgies there is a slight error on the circuit I have since corrected this

Respectfully

Mark please see revised attached

Hi Mark,

just reading back your previous post. are you saying you can provide a service to make this circuit ?

Not being able to read schematics LOL someone has also produced one for me, this I'm told has the latching facility for the button and 12V output to the sensors and output to the internal LED in the swtich ? Im not sure if you can compare against the one you have provided ?

would you be able to PM me some costs if you do make these as a service please ?

Thanks Mark

The circuit you have been given will also work but its limited in its functionality What Imean by this is at a later stage you might whish to change the length of time the relay stays on for and remains off for

You might whish to change at what point the relay energises without having to depress a button You might also whish to add remote control functionality

Agreeably, Yes it has fewer parts, however its finite in terms of its existance and its usabilty

If you consider that the circuit ive just provided can be altered to what ever i choose I can add more relays if i need too.

I can add everything I said easily and whats more all I have to do is write another peace of code or simply alter part of the code already written

With you current suggested design you cant and whats more lets also consider what the availabilty of that ic will be in lets say another six months, possibly unavailable which means one wasted pcb, lots of wasted components fixed term life span

Now consider what I have just proposed You will now notice flexibilty,functionalty and still using the same ic for possibly another 5 years or more during which i can change, alter, and I dont have to throw away

In terms of manufacture and serviceabilty, preserving the green enviroment what is more benficial

At that point Im going to let you think but needless to say I sat down this afternoon

Im halfway through putting pcb together for you because you made an effort to at the very minumum draw a diagram yourself, which told me your at least interested in what you do

Chat to you soon

Mark Harrington

Really !

That is great Mark, many, many thanks,

See attached all gerber plots for pcb plus parts list plus proteus design files C code to follow for you I do make one stipulation on this You can use design You may not remarket this or sell for any form of proffit without contacting me first to gain express permission in writing. YOU may use any project published on eeweb site under my own name to raise funds for education, training puposes within schools collegues or non profit based institutions At any rate I ask that you in turn seek eewebs permission to do so in the first instance

I will be publishing this on the net possiby later this week Dependant on spare time

You will need to double check diagrams etc to ensure no errors but to the best of my knowledge These should be correct

Best of luck and will forward you hex code approx Tues Thursday next week All being well

Its not what you do its the way do it

Hope this helps you

Best regards

Mark Harrington

I
The actual electrical design cannot be patented (too basic ), or copy righted, for one it is now public domain and second too many others have contributed in this discussion so it isn't Mark's sole propriety design. Did you copyright the schematic, then hard to enforce, hard enough even if you did.

Is the code copyrighted? If not well that would be hard to enforce.

The thing to do is stipulate an agreement before the actual design process begins. Did that happen?

This "topic" has now taken an interesting turn.
I lack quality info about (Aussie) laws in respect of Copyright & Patents, but it is sometimes surprising where copyright automatically may exist, & the effect of material being in the public domain does not generally (my understanding) preclude copyright.
I guess there will be several jurisdictions that may apply for members situated in different countries.
I'd certainly be interested in further knowledgeable comment as may apply in the members own country.
I also have little accurate knowledge of the impact of "delinquent" Asian counties who seem to have developed a reputation for disregard of international patent conventions.

I thought that might provoke interesting conversation

Copy rights public domains AND more importantly the econmics of the world, current economic decline, publishers rights, copyrights when it comes to code especially when you are talking object oriented coding

Since you inheret all other classes from topnested classes which are essentially designed and written by other software manufacturers are, or is any of the code copyrighted at all

Who does it belong too?

You could now take this even further and you could argue that since the assembly langauge belongs to microchip Does any of what you write actually belong to you or does this belong to microchip in part

Are microchip entitled to a proportion of the profit from what you in turn write for thier architecture since it is thiers in the first instance

You might also imply that all high level langauges dont exibit sole copy rights at all since they utilise underlying assembler belonging in the first instance to the manufacturers of the hardware

So within this scope is microsofts software copyrighted or do they have the right to enforce copy rights

Good question Earl What actually belongs to anyone anymore since the advent of the net and introduction of the net into the public sector?

In the meantime of course whilst people, companies are seriously debating this issue and in some cases suing each other for liable We are seeing one company after another shut down and an increasingly alarming depression set in described as the worst ever since the 1940's

The exact same events only more modernised that led to the first world war

Cetainly very intersting still best get on and write that code I guess

FYI: here in the U.S.A. As soon as someone creates something that is copyrightable, it's copyrighted. But, how to prove it -- that's the rub. Thus copyright _registration_. By registering your copyright, you gain legal muscle should you need to contest the copyright. Same with trademarks.