how to connect 555timer and ic4017 to blink the led

absf

Joined Dec 29, 2010
1,968
U1 is configured as a mono-stable. So the voltage should be stable when it is triggered.

Try to connect a DC voltmeter between pin 2 and GND of U1. What is the reading on the voltmeter when the LDR is conducting?

Allen
 

Thread Starter

freeze1010

Joined May 11, 2014
14
sorry for disturd again. i contruct it in real cct, then i found that it blinking when bright condition and 1 led light up when dark condition.

but my cct need it blinking in dark condition. can u help me again.. plz~ thx
 

ScottWang

Joined Aug 23, 2012
7,397
sorry for disturd again. i contruct it in real cct, then i found that it blinking when bright condition and 1 led light up when dark condition.

but my cct need it blinking in dark condition. can u help me again.. plz~ thx
Exchange the RV1 and LDR1.
The led show up condition that I already offered two ways.
 

absf

Joined Dec 29, 2010
1,968
I simulated your circuit and agrees with both suggestions by ScottWang. The LED would blink when the U1 trigger voltage (P2) is <1.63V and will stop blink when it is >2.00V. In my sim I used 100K for my RV1 and I think 10K is good enough for it to work. So

1. interchange RV1 with LDR1
2. Increase your RV1 from 1K to 10K

Then it should work.

Allen
 

JoeJester

Joined Apr 26, 2005
4,390
Not to change your whole design around, but have you considered using the LDR voltage source the "RESET" pins of your timer and decade counter?

This will make your monostable oscillator independent of any effects caused by the LDR, other than oscillating or not oscillating.
 

Thread Starter

freeze1010

Joined May 11, 2014
14
i get it~ldr will blinking when in dark condition. tmr i will made it to pcb board~ thx you so much every1, especially ScottWong. thankyou^^
 

ScottWang

Joined Aug 23, 2012
7,397
i get it~ldr will blinking when in dark condition. tmr i will made it to pcb board~ thx you so much every1, especially ScottWong. thankyou^^
The Wang is my family name, it means that it is King.
I drawn two ways for the CD4017 to display the leds, which way do you use?
 

ScottWang

Joined Aug 23, 2012
7,397
王 rite? haha ~
i use the no LED light up at the beginning1~ butt still will have 1 LED light up when in bright condition~
Yes, that's Chinese font 王 = King.
The situation that you described, does it turn on the different led every time when the LDR condition was changed?

If that was true then it has chance to change, but I don't have time to modify the circuit, and it needs to do the test, I have to back to the country side to do something about one week.
 

ScottWang

Joined Aug 23, 2012
7,397
Before I go back to country side, I adding a reset circuit for CD4017, if you want then you can try it, I have no time to try it, if the theory is ok, then it will no led light up when they shouldn't, no matter the LDR in which condition.

If it has any problem occur then you can try to solve it.

 

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