555 police lights (noob question)

[betwixt]

I have attached a better design that does the same thing in fewer components. I left most of the component values off but you can see how it connects together like your diagram.

Yes, changing the resistance in the current source to the 555 will change it's frequency but because you use the same signal to clock the 4017 it will also change the speed the LEDs change from red to blue.

I'm not sure what siren you are planning to use. If you connect the BDX53 to the output of the 555 it will turn on and off at flash rate which should be ~2Hz and so will give a rapid 'pip pip pip pip' sound which is probably not what you want. You can take the carry out signal from the 4017 and use that instead, it will be 1/10 of the clock frequecy which will sound better. The BDX53 will not produce a usable sound to drive a loudspeaker by itself but you can use it to turn another sound generating circuit on and off. If you want it to sound more like a police siren, use another 555 in astable mode to generate the tone and modulate it's frequency with the carry out from the 4017.

Brian.

 

[1011010]

i`m afraid i cannot find the attached file

 

[betwixt]

Sorry - try again. I hit the 'post Reply' then ran off to do another job without checking it uploaded properly.

Brian.

 

[1011010]

Hello

I am here to update you with my work, so you don`t think that you`re help was in vain. This is my final (probably, still have time to change it tough) Logic Schematics of my project and my probably not so final Layout schematic (don`t like how it looks..it probably won`t be a beautifull board , but as long as it works...) ....I am ever so greatfull for the feedback and helped, i never tought you would be so suportive, i will defenetly recomand this forum, in fact i will even include a link to it on the board next to my name .The project will remain in my university , but my teacher told me to include my name in the Silkscreen files (i think). Well i will do that only if you permit it, i don`t wanna use the name of this forum without permision. THANKS for the support . And if you find anything wrong with the Logic desing i hope you will tell me ^^

 

[D.A.(Tony)Stewart]

if the V+ (9V) is much greater than the Vf of the LED, then put them in series to share the same current and make the resistor drop less than 1 LED Vf drop.

Eg. Red/Yellow ~2.2V, White & Blue ~3.2V

 

[Audioguru]

Your schematic is a hard to see negative with a black background instead of a normal positive with a white background like on every datasheet.
You posted it on only part of the page so it is too small to see.
You saved it as a fuzzy Jpeg file type instead of as a very clear PNG file type.