On\Off and dimming with same switch?

[737mechanic]

Has anyone built a light yet with a dimming pot that also was the on\off switch. What I mean is when you turn the pot all the way it clicks off killing power to the circuit then when you turn it on you turn it to whatever level you would want. Hope I explained that good enough.

All I have found so far is using a pot with the regular push button swicth.

 

[alpg88]

if you look hard enough you'll find pots that have on off function, you just press them and shut power off in any position, i had few a while back, used them.

you could try regular household dimmer for 120vac (some have the same switching action as i described above) i don't know if it'll work with lower voltage, but it worth a try, they are like $5 at harware stores, assuming you got enough room in the light.

 

[yellow]

rotary switch

I dont like potis, imho with them it is totally impossible to get to the output and runtime one thought the light is set to.
Better is to make a few levels with fixed output, thus to be able to calculate.

on/off + "dimming" can be done relatively easy with rotary switch.

f.e. usually such a switch can power 0.5-1 A per level,
so to be on the safe side, use a few levels for ON/OFF and power, and the remaining one for the levels.

red is power, with the 1st contacts not connected for OFF
green is output choice
(here is just connects different solder pads. Instead one could wire some resistor values, or something)


PS: there are potis with a switch also, turned fully off, the switch clicks off.

 

[bretti_kivi]

yep, you get those as rotary attenuators for really, seriously high level amps (see dogbreath.de).

Taskled's drivers frequently use the same switch for power levels and on/off.

Problem: how much current can the pot switch take?

Bret

 

[alpg88]

normaly switches that you buy from radio shack, all electronics...ect are rated at no more than 500ma, usually 150-300ma, one of my projects had 3 modes, i used rotary at almost double rated current, it worked ok, didn't burst in flames, thou i wired it so it had off after every mode, and on both ends. it wasn't regulated, nor had different current for modes, just had different led clusters activated.

there are rotarys for higher current, but they are too bulky.

 

[737mechanic]

Thanks guys for your input. What I actually had in mind was using the pot with a driver. The pot would click on when turned from the off position to power the driver on and as you turned the pot it would ramp up the driver to power the LED brighter. What I would need is a driver that would work well with this and a pot with integral switch that is small enough to fit in the body of the light. The pot wouldn't have to be a high amp design since a driver is being used.

More ideas would be great.

 

[LED Zeppelin]

I believe this light by mash.m fit the bill.

He made a PWM driver controlled by the pot.

 

[mash.m]

right, my 2D mag have a pot that realise that funktion. the pot have a switch included on the left possition. this switch turn on/off the pwm driver that is regulatet by the pots resistor.
this is a very easy shematic, but hard to solder in smd. you can do this also with normal parts, but the space in a mag or other flashlights is limited.
the pots that have a push on/off switch includet like these from the home dimmer are to big and the pot have only 2 connections not 3! not usable with a driver.
i don´t like the rotary switches cause they are hard to turn, they fast damage when there is some dirt in it and you have only some steps. better then use a d2flex with 5 or 8 steps to dim.

markus

 

[Mike Painter]

Has anyone built a light yet with a dimming pot that also was the on\off switch. What I mean is when you turn the pot all the way it clicks off killing power to the circuit then when you turn it on you turn it to whatever level you would want. Hope I explained that good enough.

All I have found so far is using a pot with the regular push button swicth.

Having separate functions allows you to determine how bright or dim you want the light before you turn it on and also allows a momentary function, again at any level.
I find that far to valuable to want to have it always start high or low.

Most of the lights that have a ring work in the fashion you want.

 

[petrev]

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=CT2228-ND

? ? ?

Not very small !

 

[HarryN]

I built a light with a rotary switch with those functions in the past (off / on / 3 dimming levels). There are definite limitations, but they can be overcome.

The main advantage of a rotary switch is that it can be purchased as sealed / highly water resistant, which is much harder for other switch types. You can even obtain them mil spec if you are willing to pay the price. Space can be an issue, so it needs to be designed in from the beginning.

 

[yellow]

they really are not too small, but not this much larger than "just" a poti

another poti with switch


datasheet

 

[737mechanic]

Thanks guys. Waiting on some parts now and I am going to get started.

 

[Linger]

0-1000ma dimming control via pot and connected driver.

http://ledsupply.com/03023-d-e-1000p.php

dead simple

 

[R@ndom]

SF titan?

 

[kwkarth]

SF titan?

Exactly. Titan and T1A employ this oh, and there's the Gatlight too.