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controlling two outputs using one push button

sahil-siwatch

Jan 12, 2021
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Hello.

I want to control a single LED at three levels. I am making a blinker. 555 timer controls an LED. Initally I had one 2P3T switch which would control timer on/off (astable multivibrator), LED low brightness, LED high brightness. In short, there were three states that were switched by the 2P3T switch. But due to some issues with design, we can't use a 2p3t switch. Can I perform the same functionality with normal push button ? If there is some IC (counter or something that can be put between the switch and the timer + LED). I don't want to use any MCU as it will increase the cost.

Thanks in advance.

Sahil
 

Martaine2005

May 12, 2015
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There are Johnson counters.
But it's flip flop states would turn the 555 off when LED1 comes on.
You can use diode steering to get around this and use the 555 as a one shot monostable.
But probably not worth the effort when a switch will do.
Why can't you use a switch or MCU? They are very cheap now.

Martin
 

sahil-siwatch

Jan 12, 2021
25
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There are Johnson counters.
But it's flip flop states would turn the 555 off when LED1 comes on.
You can use diode steering to get around this and use the 555 as a one shot monostable.
But probably not worth the effort when a switch will do.
Why can't you use a switch or MCU? They are very cheap now.

Martin
I was looking at cd4026. maybe that might work...any experience with that ?
There is a MCU shortage these days... Can you suggest few cheap microcontrollers with minimum pins, maybe a pwm as well? that might be available.
My company prefers things that are done using hardware more than software for small projects like these - dumb projects basically. programming might introduce bugs.

Also what type of switches are you talking about here?
 

Martaine2005

May 12, 2015
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I would have thought most of the CD4000 series counters will work.
An Arduino mini, nano or similar. Has PWM too. I don't have any experience in MCUs but lots of members do.
As for a switch, too many to say. Rotary, toggle, slide. You'll need to explain exactly how your circuit is going to work.
I imagine switch positions : SW1 for 555, SW2 for LED low (5mA) and SW3 for LED high (20mA) as you have it already.
Give us a circuit diagram and somebody will help you.
I'll give this some thought as there will be an easy solution.

Martin
 

Martaine2005

May 12, 2015
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I am making a blinker. 555 timer controls an LED
Just had a thought but might not be suitable for your application.
You can source and sync the 555. Just change the resistor values for both LEDs to adjust the brightness.
Then you wont need any other ICs.

Martin
 
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