How to calculate on/off time with 2 Capacitors

[burrism]

Good morning. I hope everyone had a pleasant thanksgiving. I am trying to build a flasher circuit that I can adjust the on and off times. I found the attached circuit and tried it but the times are too long (I am looking for a few seconds, like 0-10 on each vice double or triple digit times). The only formula I can find to help calculate the on and off times is based on a single resistor and capacitor on the threshold and discharge pins (T=1.1xR1xC1). Is there something out there I can use to calculate the appropriate on and off variable resistors ???

TIA

 

[Delta Prime]

Hello!
Nice to talk to you again.

I am trying to build a flasher circuit that I can adjust the on and off times.

So you need a free running ,A stable, multi vibrator?(flasher circuit.)


The equation you posted is for a Monostable,one shot.(just one flash or pulse.)

(T=1.1xR1xC1).

In your schematic, you have two Zener diodes designated as D1 and D2. Are those two LEDs you wish to have flash for maybe one to 10 seconds Back-and-forth, off & on?

 

[burrism]

Hello again Delta Prime! So the Diodes are just in there, not sure why they are there but they are not LEDs. The schematic is not my design, I saw it at the video associated worked like I wanted it to, so I copied it but the resistor and capacitor values are off. My ultimate goal is to replace a vehicle turn signal relay that blinks too fast (rapidly) for my sequential LED application. I would like to control the on and off times so I can ensure my LED sequencer makes it through the whole sequence before it starts over. I would also like to have the potential of using this for other applications as well otherwise I could just make a monostable timer with set on and off times using the formula I had.

 

[Delta Prime]

would like to control the on and off times so I can ensure my LED sequencer makes it through the whole sequence before it starts over.

No problemo.
Take a look at this online 555 timer calculator, courtesy of; the one & only… @bertus

Good Free 555 Timer Calculator Program?

I was using one for the last few years that I really liked, but newer operating systems and other computer changes over the years have made it less and less compatible with anything I own, and I can't find an updated version. It looks like this: Any suggestions? Looking for one that can...

forum.allaboutcircuits.com

 

[Bluejets]

Try these simple enough.....
https://www.talkingelectronics.com/projects/FlasherCircuits/Page83FlasherCircuitsP1.html

 

[burrism]

Try these simple enough.....
https://www.talkingelectronics.com/projects/FlasherCircuits/Page83FlasherCircuitsP1.html

Thank you sir. those look interesting but I do not see any of them with adjustable blink rate.

 

[Bluejets]

I'm not about to hold your hand like a primary school kid....look for yourself on that site.....there are plenty.
https://www.talkingelectronics.com/te_interactive_index.html

 

[danadak]

Could always do this with ATTINY85 and simple code.



The above is mBlock, you code by drag and drop and config blocks, and it generates
Arduino code to use.



Regards, Dana.