Schematic #19 - U3A can be replaced by two small signal diodes (1N914, 1N4148, etc.), eliminating an entire IC.

Here's aks modification in the schematic.

 

Thank you for schematic and the two diodes solution.

The LED is going in to a Door bell and it will be illumination 24/7. How long will it last with this circuit compared to a LED driver?

 

I'm confused. If the LED is going to be on "24/7", then what are all of those parts for?

And why do you think you need the expense of an LED driver? With a single LED (of *any* type) and a fixed DC supply, why not just 1 resistor?

ak

 

Please read #1 again if you are confused. The circuit will run 24/7... And because the LED only will be OFF for 9 short moments when pushing the button, I consider the LED to be ON 24/7.

The reason why I think I need an LED driver is because I've read that LED Driver will extend the life of the LED. Because the LED is lit 24/7 I expect the load to be more stressful to the LED than if I only turned the circuit on once in a while.

 

The reason why I think I need an LED driver is because I've read that LED Driver will extend the life of the LED.

Not in this case as the current required is small. A single resistor R5 to set the brightness level should suffice eliminating RV1 and possibly even Q1 as the 4017 can source over 5 ma at 12 volts.

 

The reason why I think I need an LED driver is because I've read that LED Driver will extend the life of the LED.

That may be true for some specific situations, but as a general rule - no. Read the datasheet, operate the part within its forward voltage, reverse voltage, current, and temperature boundaries, and you will get its standard lifetime, which is years. Operate it at less than it's recommended current and the lifetime increases.

ak

 

First of three concept schematics. U1 is a quad NAND gate with Schmitt Trigger inputs.

R1-C1 sets the time the LED is blinking. R2-C2 set the blink rate. C3 is the power supply decoupling cap. When C1 is discharged, U1 pin3 is continuously high and the LED is on. When C1 is charged up through SW1, U1A starts to oscillate, periodically turning off Q1 and the LED. The LED blinks as long as the button is held on, and for approx. 10 seconds after the button is released.

ak

 

Second concept schematic. If the LED current isn't too high, you can use the unused gates in parallel to drive it directly.

ak

 

Third concept schematic. By changing to a hex gate, you now have five gates in parallel driving the LED. Since the gates are simple inverters, D2 is added to inhibit the oscillator.

ak

 

I opted for the 74HC132 since it can drive an LED (or I can parallel outputs).
Had to add a 5.1v zener though.

 

Had to add a 5.1v zener though.

That's why I stuck with 400x. My favorite CMOS line is the 74AC variety (+/-24 mA output current), but again, 5 V.

Also, despite what the datasheet says, I've found that HC parts, like 400x parts, are better at sinking current than sourcing.

And speaking of sourcing - the TS wants the LED to be ON continuously between button presses, not off.

crutschow will be happy about R4 being in series with C1.

ak

 

First of three concept schematics. U1 is a quad NAND gate with Schmitt Trigger inputs.

Now that looks a lot simpler! I'll try it out.
I have to see if I have a 4093.

 

I had one 4093!

I don't have a 2n7000 though. Would a 547 work? or a 2n2222?
I also have this kit:

 

I had one 4093!
I don't have a 2n7000 though. Would a 547 work? or a 2n2222?

You don't need the transistor. Use the circuit ak posted in #28.

 

Thanks I'll try that immediatly.

 

Any small-signal NPN transistor will work in place of the 2N7000. Add a resistor in series with the base, anything in the 2.2K to 7.5K range.

Can you post a link to the datasheet for the LED you want to use?

ak

 

It goes like this
https://www.youtube.com/shorts/jSb6FjVFSRA

 

Can you post a link to the datasheet for the LED you want to use?

no I'm just a hobby guy that uses cheap cheap LED's from aliexpress. Not sure if they even put out a datasheet.

 

I would love to see a animation/simulation on how the circuit works if anyone has such a program.
I may have to look into what a schmitt trigger is too.

 

I opted for the 74HC132 since it can drive an LED (or I can parallel outputs).
Had to add a 5.1v zener though.

Pretty much a simillar circuit right? although it flashes differently?