I have quogled for NE-555 online calculators and - of course - found multiple of them.
But all the ones that I found work this way
choose mode: astable
input capacity
input R1
input R2
get the results for
frequency
On-time
Off-time
with this kind of calculator I would have to play around a very long time to finally get a combination that does
have a period of 35.000 milliseconds
on-time 1 millisecond
offtime 34 milliseconds
Does somebody know of a NE-555-online-calculator that is able to calculate
capacity, R1 and R2 for a given combination of
period, Ontime and offtime ?
I guess this must be done by a software that does a numerical aproximation by sweeping the values of capacity, R1 and R2
Yes, for me I can enter the frequency or duty cycle and it gives me the R and C values. I don't know if it's because I have the pro version or maybe a different revision, etc.???
thank you very much for answering. I finally was able to calculate the values.
I was assuming too fast it can't do it.
Very interesting to getting to know the possible applications and the limits.
If I understand right you can achieve a wide range of frequency and duty-cycles from 0,X Hz up to 500 kHz.
But as the determing components the capacitor C and R1 and R2 are in series varying one value has a direct effect on the other two values too.
This means if you want to adjust for example the frequency to a certain value by changing capacity this will require to change R1 and R2 too to keep the same dutycycle. And this effect occurs for changing dutycycle too.
So from this I have learned that the NE-555 can produce a wide range of frequency and dutycycle but adjusting to very precise values is an iterative process of adjusting all three C, R1, R2
Not necessarily. There is a circuit with 2 rectifier diodes added so that the two ON and OFF times can be adjusted independently. With the 555 timer I never got accurate results as predicted. Even the datasheet statement that frequency is independent of supply voltage is not entirely true. I have actually used a 555 timer very little and that was many years ago. Honestly now I'd rather program some kind of microcontroller for the purpose instead of having to deal with the limitations of a 555 timer.