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Simple 555 timer circuit

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mark_3094

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Hi,

I am trying to use a simple 555 timer circuit that flashes an LED (as shown in the attachment), but I want it to flash for a while, then have the flashing slow down to a stop, like in an electronic dice circuit.

I have seen a circuit with a capacitor in parallel to the RC timing components, but I can't seem to get it to work.

Can anyone help me?


Thanks
 

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  • 555 LED Flasher.jpg
    555 LED Flasher.jpg
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Instead of connecting R1 to the positive supply, have a capacitor feed R1. When the capacitor is charged then the circuit works like the original circuit.
When the capacitor discharges into R1 and the other parts then its voltage slowly drops and the frequency will get slower until it stops.
 
555 Timer Decaying Frequency

Thanks fo your help.
I have uploaded a schematic that works if it is of any use to anyone else.
If you can think of any improvements, please let me know.
 

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  • Decaying Frequency.jpg
    Decaying Frequency.jpg
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555 Timer Decaying Frequency

Can anyone explain why the LED is always on as soon as the power is connected?

Thanks


-- I figured this out...
The voltage on pin 2 (the trigger) is 0v, which is less than 1/3rd of the source voltage on pin 8.
This means that the timer is 'started', which makes the output (pin 3) go high.
 
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