use only 2 pins of pots when used as var res.

hi,
That is not recommended, always link the centre tag to one of the outer tags.
E

 

hi ikuss,
I have already explained about the pot wiring.

This is your circuit's 4 states for the Mark and Frequency pot Limits

Study it.
E

 

What is the exact part number of the '555 you are using?

NE555P

 

So I removed the pots and put one pot and a resistor . Why the freq pot changes not the frequency of pulses but the intensity of LED light? at max it stops the led...its frustating

 

Your first schematic, which you posted twice only gives accurate results when used with the CMOS version of the part, and your is not - it is the bipolar part, in which case you need to connect the RC timing network to the power supply, pins, 7, 6, and 2, as shown in ericgibbs's circuits shown in post #22.

With the bipolar NE555P pin 3 is only useful as an output, not to drive the timing network.

 

ok the frequency is not accurate , I wired the circuit as that, but why the potentiometer varies the current-led intensity and not the frequency? I burned one while trying to wire it everyway.

 

hi,
How is the LED connected to the 555 output.?
E

 

pin 3-1k resistor-LED

 

Has anyone built this circuit and it worked fine ?

 

hi ikuus,
Is the purpose of this project to control the light output of an LED, say from dim to bright.?
E

 

Cha

ok the frequency is not accurate , I wired the circuit as that, but why the potentiometer varies the current-led intensity and not the frequency? I burned one while trying to wire it everyway.

How do you know the frequency isn’t changing? With the calculated values, what’s the frequency range you’re expecting? Any frequency over 50Hz won’t be visible. It might affect the brightness.

 

hi ikuus,
Is the purpose of this project to control the light output of an LED, say from dim to bright.?
E

No, the purpose is to make the led flash at different frequencies and pulse widths.

 

hi,
The simulation shows with those component values, the slowest flash rate is about 5 per second.
Try increasing the 4.7uF to say 10uF or 22uF

E

 

hi ikuss,
Look at this option,
100K pots and a 10uF

If you don't have 100k pots, use 50k pots and a 20uF cap
E

 

Cha


How do you know the frequency isn’t changing? With the calculated values, what’s the frequency range you’re expecting? Any frequency over 50Hz won’t be visible. It might affect the brightness.

because the frequency was constant at 1 flash every 6 seconds , but I have an extra 555 and replaced it now it seems to work//// it was a new one, they can be broken from factory it seems.

 

hi ikuss,
Look at this option,
100K pots and a 10uF

If you don't have 100k pots, use 50k pots and a 20uF cap
E
View attachment 255737

what software you use? its free?

 

hi ikuus,
It is LTspice, free download, many users on AAC who could help you learn.
E
https://www.analog.com/en/design-center/design-tools-and-calculators/ltspice-simulator.html

 

Why in the usual astable circuit if I use a potentiometer in place of R1 if I turn the knob to the lowest resistance the LED is off and the pot makes sparks? It works with a resistor.