Help figuring out this circuit from a toy.

Hey guys. Pulled this flashing LED circuit out of a toy. Here is a drawing of what it looks like. Much appreciated if you could help me replicate it! I apologize for the bad drawing, but I'm a novice.

**broken link removed**

It is an LED flashing circuit where the red one flashes twice then the blue one flashes twice and repeats.

Can anyone tell me how to replicate this? Or create a new circuit that does the same thing... that is easy to make?

Thanks!

AndyLinde said:

Hey guys. Pulled this flashing LED circuit out of a toy. Here is a drawing of what it looks like. Much appreciated if you could help me replicate it! I apologize for the bad drawing, but I'm a novice.

It is an LED flashing circuit where the red one flashes twice then the blue one flashes twice and repeats.

Can anyone tell me how to replicate this? Or create a new circuit that does the same thing... that is easy to make?

Thanks!

Click to expand...

hi,
The black thing is called a COB, chip on board, under the black goo is a small IC die.

You could do the same flashing of two led's using a 555 timer 8 pin IC..

Thanks Eric! Can you (or anyone else) explain which pins of the 555 IC I need to attach everything to so I get the flashing pattern I described? (red flashes twice, then blue flashes twice, etc. quite fast)

I have looked online for schematics but none of them explain how to get this specific flashing pattern. Many thanks!

How many LEDs do you what to use? What power soarce will you use? Andy

AndyLinde said:

Thanks Eric! Can you (or anyone else) explain which pins of the 555 IC I need to attach everything to so I get the flashing pattern I described? (red flashes twice, then blue flashes twice, etc. quite fast)

I have looked online for schematics but none of them explain how to get this specific flashing pattern. Many thanks!

Click to expand...

I personally would use a 556, which is just two 555s in one chip. I'm not exactly sure how you'd get that particular flashing pattern, though. The best way I can think of would be a programmable chip, which is relatively complicated and expensive.

DerStrom8 said:

I personally would use a 556, which is just two 555s in one chip. I'm not exactly sure how you'd get that particular flashing pattern, though. The best way I can think of would be a programmable chip, which is relatively complicated and expensive.

Click to expand...

hi DS,
For a simple device I would use say a 555 and a 4017, 4 signal diodes would give the required led pattern.

DerStrom8 said:

I personally would use a 556, which is just two 555s in one chip. I'm not exactly sure how you'd get that particular flashing pattern, though. The best way I can think of would be a programmable chip, which is relatively complicated and expensive.

Click to expand...

I think the better question is "why do they want to replicate the device"? If it were for a one-off project, then it would probably be easiest and cheapest to just use the part from the toy. However, if they were wanting to replicate it for their own product, where presumably they would be manufacturing (in some manner) more than one, then using a programmable chip (like an 8-pin PIC or AVR) would be the least expensive way to go in large quantities (the expensive part of using a microcontroller for such a simple task is the time needed to learn the programming, plus the programming hardware - but those become sunk costs which can be applied to future projects, and would be a small percentage of the total manufacturing costs - provided they were making more than a few hundred of the devices).

I would be willing to bet that the blob on that device is a small microcontroller of some type (because of the above).

If it is a one-off need, and the OP is wanting to replicate it (rather than reuse the PCB) - then a microcontroller might still be the best option, even if it is more expensive to start with. Embedded controllers are where things have gone; you just don't see discrete logic and such used that much any more, because with a microcontroller (among other tools), you can get all of that (which includes the ability to implement upgrades and modifications) in a smaller, lower-pin-count package.

With that in mind, the OP should go that route if they figure they'll ever have the want or need to build other projects in the future.

Use the search here, there have been quite a few 'police flasher' circuit discussions in the past, and several tested circuits posted. Microcontrollers aren't all that expensive or complicated anymore. There are several under $1.00, that would be overkill. AVR software is free, and there are some cheap/free methods for programming the chip. Tons of tutorials covering this particular subject, as most everyone starts by flashing a LED...

cr0sh said:

If it is a one-off need, and the OP is wanting to replicate it (rather than reuse the PCB) - then a microcontroller might still be the best option, even if it is more expensive to start with. Embedded controllers are where things have gone; you just don't see discrete logic and such used that much any more, because with a microcontroller (among other tools), you can get all of that (which includes the ability to implement upgrades and modifications) in a smaller, lower-pin-count package.

With that in mind, the OP should go that route if they figure they'll ever have the want or need to build other projects in the future.

Click to expand...

I was trying to avoid the microcontrollers simply because of their complexity. I agree that, overall, PICs might be the best choice, but for someone who hasn't had any experience with them, it is fairly difficult to get used to the programming, etc. I think ericgibbs' idea would be the best bet at this point because of the availability of the parts.

It's really not as bad as it sounds, I taught myself (still need to learn, but does it ever end). I brought it up, because this is exactly the sort of project to get started with microcontrollers, even a PIC . They really are only as complicated as you want them to be. Nigal has some great tutorials, might be worth a quick look, and see just how bad it is for you. I found them useful, and never touched a PIC. Three ICs, just to flash two LEDs is complicated, least for the task.

Did you dig through the past threads? There were several cleaver, non-microcontroller solutions. Think it was around the beginning of the year, or shortly after. Might look back later, but would go back to building circuits like that.

Here's one with only two chips, 4001 and 4017... https://www.electro-tech-online.com/threads/how-can-i-build-that-flasher.35516/

This project creates the pattern you want:

**broken link removed** It can be programed by you to create any pattern. LED FX

ERic's is the one.

I second Eric's suggestion. Unles the OP wants to spend lot of time learning how to handle the simplest (?) micro to flash those LEDs.

In this context, "lot of time" in comparison with the mentioned solution.

Are we launching the rocket now?

AndyLinde said:

Hey guys. Pulled this flashing LED circuit out of a toy. Here is a drawing of what it looks like. Much appreciated if you could help me replicate it! I apologize for the bad drawing, but I'm a novice.

It is an LED flashing circuit where the red one flashes twice then the blue one flashes twice and repeats.

Can anyone tell me how to replicate this? Or create a new circuit that does the same thing... that is easy to make?

Thanks!

Click to expand...

hi,
This simple circuit will give you the same flashing pattern, you can also change the pattern and rate, no programming required.
Get the datasheets for two IC's for the pin numbers, shout if you have a problem.