I can find timer circuits to blink an led but I would like to have a circuit that causes an led to continuously blink after it is actuated by a voltage pulse. Not sure about the pulse voltage but since it normally operates a small speaker it is probably a small and sufficient voltage. My operating supply for the circuit will be 5v, and I need 3v? to the led. I need a momentary switch for resetting the led. I can experiment with component values to get the blink rate to my liking. Can anyone give me a simple circuit for this? Seems like it would just take two transistors or an ic. 555? 547? Thanks.

 

Not nearly as simple as you think. The voltage to a small speaker is AC and likely too low a voltage to activate a transistor, so it will need amplification. And then there is the latching action. Your circuit needs a memory element to know whether it has seen the start signal or not. The reset function should be easy.

 

I suppose I would be able to use the dc to the internal led from this actuating alarm circuit instead which flasheses more than once.

 

"" Not sure about the Pulse-Voltage ""
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A complete definition of the "Pulse-Voltage" is the most important aspect of this project.
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Ok, I will get that info.

 

Ok, I will get that info.

Why not tell us exactly what you are trying to do? This is the biggest mistake by most posters. From your second post, it sounds like the source is some kind of alarm. Why do we have to guess?

 

Can anyone give me a simple circuit for this? Seems like it would just take two transistors or an ic. 555?

C1 and R1 control the blinking rate.

 

Wow. Thank you very much. I will get some more parts and try that. Do you know if a NE555 would work or stay with your exact item?

 

The NE 555 output stage can supply more current than the CMOS LMC555 can to a load. However, it also has a smaller output voltage range. If you need a full 3 V across the LED, this might be an issue.

What LED current do you need?

An alternative is using a CD4093 quad NAND gate as both the set-reset latch and oscillator, driving a 2N7000 small FET to drive the LED.

ak

 

Do you know if a NE555 would work or stay with your exact item?

It can with a few component changes. May need Q1 depending on how much current the LED requires.

 

Ok great. I will be working on this and get back. Thanks again.

 

Ok great. I will be working on this and get back. Thanks again.

What LED are you planning on using?