Turning a light on and off with momentary switch

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Yes, a flip-flop would do it and someone is sure to suggest a PIC, both requiring a fair amount of extra components to actually work. Have you looked for alternate action switches or relays? It would run your lights and not require a degree to get it to work. Glenn Gundlach

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stratus46
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I want a circuit that will turn a light on with the press of a momentary switch and then turn it back off when the momentary switch is hit again. I had heard that a flip flop might be the way to go. After some reading, I have found that a flip flop is a much more complex device than I was lead to believe. I think a flip flop would some how do the job, but it is going to take some more reading before I figure out how. If you have been reading some of my other posts, you know that I want to turn on and off more than one light, so I need several of these circuits, preferably using the minimum number of components.

Another option I would like to explore is to turn the light on and off using 2 inputs. Say we have in put A and B. If input B is high, when input A goes high, turn the light on, or leave it on. If input B is low, when input A goes hight, turn the light off, or leave it off.

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Chris W

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Reply to
Chris W

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No.
Reply to
John Fields

Is that because flip-flops require capacitors to store state information? I would be interested to know the minimum complement of components necessary to support a single flip-flop. Perhaps there is a good link to this kind of information (?)

I have a similar request as the original poster. I would like to use a momentary switch to cycle among three LEDs. Is the circuit design for this using flip-flops complex? Is there an easier way to generate the same functionality? It seems that there must be some ICs out there that provide this kind of functionality out of the box. Does anyone know of any?

Thanks a lot! Peter

Reply to
Peter Michelson

this

provide

Thanks for the ideas! Also, interesting link. Regards, Peter

Reply to
Peter Michelson

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The driver would be the device/circuit sending the information to the
flip-flop which would cause it to flip or flop.
Reply to
John Fields

Thank you for your reply.

necessary

Is there a more specific term for "driver"? I am not familiar with a component by that name.

this

Good point. Simple for me means that few (e.g., less than 5) components are involved and testing can be done with a multimeter.

As I said, I would like to cycle among three LEDs. To elaborate: one LED is turned on at any given time; each time I depress the momentary switch, I would like the LED that is on to turn off, and the next LED in sequence to turn on; the first LED is considered to follow the third in a cyclical manner. I imagine that this circuit is functionally similar to one that would drive marquis lights, except that instead of using a timer chip, it is user-driven.

I hope the more complete description above is easier to understand than the one in my first posting.

Is there one in particular that is best-suited to the functionality described above?

Thanks again for your reply.

Reply to
Peter Michelson

A flip-flop basically stores a 1 or a 0, ON or OFF, respectively. It can't switch between the two by itself. It needs additional circuitry to drive it, or basically tell it when to switch the flip-flop from 0 to 1, and 1 to 0.

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A component might be an IC, or a PIC which might be pretty advanced for an electronics hobbyst.

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A PIC would suit perfectly for this type of application but it requires some funds for a PIC programmer (hardware) and coding the PIC (software). You'd have to know how to program to use a PIC.

the

Reply to
John

Don't let a little flip-flop stop you. You should research the T flip-flop and a debounce circuit for your clock input. That's the button that makes it do it thing Chris, not a time of day clock!

Reply to
Lord Garth

You can use an led chaser kit to do the sequental leds. You can use just the first two outputs on the chip for flip-flop. I've got a page below showing some tinkering with the 4017 decade counter chip that might be useful.

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Reply to
Si Ballenger

is

Indeed :)=) One wonders what, exactly, a "marquis light" would be.

That's very kind.

Reply to
Peter Michelson

Thank you for your reply.

it,

what are the characteristics of the signal required to cause the bit to change?

some

Does PIC stand for Programmable IC? Is this similar to an EPROM or PROM? How much does PIC programmer hardware cost?

What skills are necessary for programming to use a PIC? For example, if one is versed in machine language, is that sufficient?

Thanks for the information. It sounds intriguing. Regards, Peter

Reply to
Peter Michelson

For the first application I just want to switch 1 or maybe 2 LED's hooked in parallel. They could be of different colors and therefore different voltages so I am guessing even for just one led on each line I probably need some kind of a driver so I can match the voltage and current for each load. Future applications will need to switch around

10W lights, probably in the form of groups of LEDs, on and off.

After some more reading on flip flops I figured this out on my own. If you read my post in 2-14-2005, you can read more about my application. What I would really like to find is an IC with as many as 16 D flip flops that are already wired up like you described. I don't suppose finding that is likely?

I'm thinking about getting one of the RABBIT modules, that way I don't think I need a separate programmer do I?

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Chris W

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Reply to
Chris W

can't

  1. > >

A flip-flop STORES a signal. So basically it stores whatever signal you feed it. For your project, you don't need a flip-flop if you use a PIC.

You'd

Yes. EPROM. You can get one for around $150US

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one

Some are assembler, some are C/C+, some you can use BASIC.

Microcontrollers are the easiest ways to create your own electronics devices given you know how to program.

Reply to
John

"Chris W" schreef in bericht news:2OOQd.63983$jn.59042@lakeread06...

Chris,

What kind of lights do you want to switch? It makes a lot of difference whether you want to switch a LED (~40mW) or a 100W incandescent bulb.

The most simple solution I can imagine is a tablelamp pushbutton switch. Conrad sells them for ?2,20 but I guess you can do cheaper locally. It does exactly what you describe. Push on, push off, push on, push off and so on.

A more expensive but still simple solution goes with a relay of the same voltage as the lamp, a make- and a break pushbutton. Conrad sells relay from below ?2,-- upward and pushbuttons from below ?1,00 upward depending on voltages and currents required. Digikey will sell similar components but I have no catalog at hand.

LEDs can be controlled easily using electronics and that's where the flip-flop appears. You need a so called T-flipflop but they are not very common. Use an D-type flipflop instead and connect the inverted Q-output (/Q) to the D-input. Every pulse on the clock input will make the flipflop change state. So a pushbutton on that input will theoretically do the job. But a flipflop is a high speed switching device and will see a lot of pulses every time you push and you can not predict the last one. So you need to debounce your pushbutton carefully which requires some extra electronics.

Of course you can use a microcontoller as wel. Microchip sells 6 pins ones these days and the only extra components you need is the pushbutton, the LED and maybe two resistors. The problem of course is skills and equipment to program them.

petrus bitbyter

Reply to
petrus bitbyter

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Reply to
John Fields

Here are three practical circuits you can experiment with:

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Terry Pinnell
Hobbyist, West Sussex, UK
Reply to
Terry Pinnell

There is a "10 stage LED sequencer" at the below address. You will need to change the 555 oscillator into a

555 "one shot" circuit so you can use a pushbutton. The 4017 can be used for just 3 LEDs by connecting the reset line (pin 15) to the 4th output, (pin 7).

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-Bill

Reply to
Bill Bowden

There is a "10 stage LED sequencer" at the below address. You will need to change the 555 oscillator into a

555 "one shot" circuit so you can use a pushbutton. The 4017 can be used for just 3 LEDs by connecting the reset line (pin 15) to the 4th output, (pin 7).

formatting link

-Bill

Reply to
Bill Bowden

One or two LEDs in series can be driven by some logic devices. For more LEDs or lamps you will need a transistor driver or a relay.

Missed your post of 2-14-2005. Can't even find it in the Google groups.

AFAIK such a device does not exist and its very unlikely you'll ever find one. You can design one for yourself using PLDs but that requires quite some skills and programming equipment. Especially if you want to incorporate debouncing. Even then you wil need power drivers to control loads over some hundreds of mW.

FAIK RABBIT devices also requires programming which can be done using C. You will also need a pretty expensive development system and the modules themselves does look like to be cheap either.

Did you realise a module like you want, needs at least 34 pins? I think a 40 pins micro comes most close to that. A PIC16F877 is one of the cheaper

Reply to
petrus bitbyter

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