I bought a alarm clock kit for my project. I wanted to connect this kit with another circuit that I made which contained several LEDs which will light up gradually. I was thinking of powering the LED circuit from the kit's output; buzzer.
However the issue is, When I did connect the LED circuit to the kit the LEDs started flashing due to the pulsing power output.

Is there a way I can possibly change this pulsing output to constant and stop the LEDs from flashing?

I know for sure that the LEDs i used aren't flashing LEDs as i have connected it separately to a PSU and the leds didnt flash.

I don't really want to change the kit's function as it physically cannot be changed.
I tried making a bridge rectifier circuit, but it didnt work as the power going in the kit was DC.

Could you please suggest ways i could solve this problem?

Click this link to see the details of the alarm clock kit that i used

Thank you

 

Any possible solutions?

 

Hello,

The flashing is programmed in the used chip.
If you want a steady output, the program needs to be changed (wich is probably uknown).
An other possibility is feeding the flashing signal into a retriggeble monoflop.

Bertus

 

You can use a simple missing pulse detector circuit. How fast do the LEDs flash? Slow on-off pulsing, or fast flicker like the buzzer?

Ken

 

You can use a simple missing pulse detector circuit. How fast do the LEDs flash? Slow on-off pulsing, or fast flicker like the buzzer?

Ken

They flash slow on off, on for 2 secs and then off for 2secs.

 

Attached is a retriggerable monostable 555 timer circuit. Each time the buzzer output goes high, the 555 timer's output (pin 3) goes high and stays there for ~3 seconds after the buzzer goes low. Since you buzzer goes high for 2 seconds once every 4 seconds, the output will stay on. You may have to play with the values for R4 and C1. My values were just a quick estimate. The TTL version 555's output will handle 200mA max, while the CMOS version's output can handle only 100mA.

Ken

 

Attached is a retriggerable monostable 555 timer circuit. Each time the buzzer output goes high, the 555 timer's output (pin 3) goes high and stays there for ~3 seconds after the buzzer goes low. Since you buzzer goes high for 2 seconds once every 4 seconds, the output will stay on. You may have to play with the values for R4 and C1. My values were just a quick estimate. The TTL version 555's output will handle 200mA max, while the CMOS version's output can handle only 100mA.

Ken

Thank you for the diagram and a quick response. My only question is will this circuit work for output with longer on/off delays, for e.g. on for about 5secs and off for another 5secs

 

Yes. It's just an matter of increasing the on-time by increasing the values of R4, C1, or both. Doubling the value of R4 or C1 will approximately double the on-time. Doubling both will increase the time by ~X4.

Ken