Control 2 outputs with one push switch.

Thread Starter

sahil-siwatch

Joined Jan 12, 2021
43
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
 

Thread Starter

sahil-siwatch

Joined Jan 12, 2021
43
Do you know that something like the ATTiny5 is less than .50 USD? I am not sure you can get much cheaper with some other components and you will certainly not be as flexible.
whereas 555 timer costs 0.08USD. and also the ssemiconductor shortage is causing problems. Not desirable for a project which will be produced in quantities of thosands.
 

Yaakov

Joined Jan 27, 2019
3,190
whereas 555 timer costs 0.08USD. and also the ssemiconductor shortage is causing problems. Not desirable for a project which will be produced in quantities of thosands.
So you have a solution that uses a 555 without enough support components to overrun your budget?

My point is that you are prematurely optimizing. Without investigating the options, you don’t really know the cost of an MCU-based solution. You don’t even have a proposed circuit that doesn’t use an MCU.

Entirely friendly advice: set out the problem and the constraints, but don’t make the constraints guesses. The constraint is cost, but what if an MCU-based solution is the same or cheaper?

Good luck.
 

Thread Starter

sahil-siwatch

Joined Jan 12, 2021
43
So you have a solution that uses a 555 without enough support components to overrun your budget?

My point is that you are prematurely optimizing. Without investigating the options, you don’t really know the cost of an MCU-based solution. You don’t even have a proposed circuit that doesn’t use an MCU.

Entirely friendly advice: set out the problem and the constraints, but don’t make the constraints guesses. The constraint is cost, but what if an MCU-based solution is the same or cheaper?

Good luck.
Thanks for your suggestion :) I have both the circuits in mind. 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.
 

Yaakov

Joined Jan 27, 2019
3,190
Thanks for your suggestion :) I have both the circuits in mind. 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.
The ATTiny processors are an excellent possibility but there are others on the forum who will certainly have suggestions such as PIC which they use extensively. As far as bugs, they areno more likely inan MCU design than pure hardware. It’s not as if after testing you are going to update the firmware. If it passes QC it stays working.

I want to be clear I am not advocating an MCU at this point only not ruling one out given the possible considerable advantages they offer. There’s a reason they are in almost every consumer item now, even the cheapest.

By the way there are very low cost MCUs used in Chinese designs. I know they exist though not much about them.
 

click_here

Joined Sep 22, 2020
217
When you get in the 1000's the manufacturing (parts + assembly) becomes the dominant cost.

Wouldn't you want to minimise the components and PCB size like Peter has suggested?
 

Ian0

Joined Aug 7, 2020
2,289
How about a 4017?
Connect the "0" output to the 555 RESET.
Use the "2" output to force the LED on (Diode OR with the 555 output)
Connect "3" to reset to start the cycle again.
COnnect the pushbutton to the 4017 clock with a bit of debounce.
(But a 4017 is bigger than the ATTINY, but you don't have to find a way to program it)
 

MaxHeadRoom

Joined Jul 18, 2013
23,150
. 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.
Most of the 8 pin series Picmicro from the 12F683 to the 12F1822 has many features.


1622233352602.png
 

AnalogKid

Joined Aug 1, 2013
9,261
Please expand your original question with moe detail. What is the available power supply voltage? How are you varying the brightness now?

Please post a list of the functions you want each time the button is pressed once (first press, second press, etc.).

Also, please post a schematic of the way it is wired now.

AND - "we" ?? - Is this a school project, a commercial product, or something else?

ak
 
Top