# need diagram for LED Police lights

Joined Apr 22, 2010
22
Hello, I have a little electronics knowledge but not enough to make a LED police light system for a RC car, and would really appreciate some help from a pro....what Im looking for is a diagram & parts list to create the following which will run off the car battery 7.2 volt 4500 - 6800 mah Ni-Mh..... 12 x 10mm LEDS (high brightness) 4 x white 4 x Red 4 X Blue...
group 1 = 2 x white, 4 x Red LEDS
group 2 = 2 x White, 4 x Blue LEDS

group 1 flashes strobe effect , say 3 times per second
then 1/2 second after
group 2 flashes strobe effect , say 3 times per second
then 1/2 second after
back to group 1 ....this pattern is continuous

I will put a small switch on the power lead.

I hope my instructions are easily understood, and really would appreciate
any advise and help I can get...

thankyou. !!

Joined Apr 22, 2010
22
thanks Bertus, but like I said, I am very limited in electronics knowledge and I dont understand all of those pics, I can work out some of it, but unsure about some too...my memory has to go back to school days...lol

#### Wendy

Joined Mar 24, 2008
23,134
No problem, but you will have to relearn them old skills.

Check these out...

The 555 Projects

Meant specially for beginners, they are very diagramed out.

The AAC text book whose chapter are on top of this page are also meant to teach.

The project closest to what you want to do is 555 Hysteretic Oscillator . I can also help design specialty circuits if asked nicely.

Joined Apr 22, 2010
22
thanks Bill, I m having trouble understanding it, I might go to my local electronics store and see if they can build it for me, I know this might sound strange but if the diagram was drawn like a photo of the pcb I could just copy it, but being a schematic diagram it just dosent make sense....

#### Wendy

Joined Mar 24, 2008
23,134

Joined Apr 22, 2010
22
i had a look at the 555 hysteretic oscillator and I understand everything except the numbers on the chip...I take it that the numbers are the legs..??...are the legs numbered from 1 ,2,3,4,,5 etc.etc clockwise..???

Joined Apr 22, 2010
22
OH WOW...thats better, I can see it really clearly...thats how all diagrams should be...LOL...(high power led flasher)

Joined Apr 22, 2010
22
but I still need 12 LEDS in the circuit.!!

Joined Apr 22, 2010
22
the reason why I still need 12 LEDS is beacuse that is the lighting configeration for the australian unmarked police cars....2 white for headlights..1 red/blue grill, 1 red/blue windscreen, 1 red/blue each side of back window, 2 whites reverse lights.

I have found someone in USA that can build them for me $40 +$20 postage...I would love to be able to make them myself for \$10.....so Mr Marsden , I would love for you to help me and make a "EASY" to follow diagram , I would even pay you ...name your price......thankyou

#### Wendy

Joined Mar 24, 2008
23,134
Tell you what, I'll do it, but no price. You asked nicely.

Review this thead, and come up with a layout on your car similar to the one in this thread.

If you can understand the pattern you want it would help (simple alternate lights are OK). The one shown in the above thread are double flashing lights under the grill and alternate on the top.

I'll also need the battery voltage.

Last edited:

Joined Apr 22, 2010
22
oh thankyou sooo much Bill...you are a champion...Im using a 7.2 volt 6800mah Ni-mh battery...I looked at those pics and Im not too sure about how to make my light set up look like that on a pattern....but basically I will be running 12 bright LEDS.........

Group 1 = 2 x white , 4 x Red
group 2 = 2 x white, 4 x blue

Group 1 are to flash 3 times per second
then 1/2 second gap
group 2 are to flash 3 times per second
then 1/2 second gap

this is continuous....

as long as they flash like that, I can just position them in the correct spots on the car via wires.....I hope you understand my uneducated electrical mind...lol...I'll put a small switch on the power lead.

thankyou very kindly.

Last edited:

Joined Apr 22, 2010
22
Here is a picture of what I would like....thankyou Bill.

#### Attachments

• 212.8 KB Views: 109

#### Wendy

Joined Mar 24, 2008
23,134
What part of the world are you in? This will affect the parts I recommend. Some parts are harder to get than others.

You might think about buying a protoboard similar to what I show in the 555 projects series. It will let you check designs out before you apply solder, which is a plus.

If you're not inclined don't worry about it. The other component you will need early in this process is a breadboard, the little circuit boards you will be using to build them on. This is so I can draw it, and use it in the documentation. You can use either 2 555s or one 556 (which is two 555's in one package). Let me know which you want to use early too. I would also recommend getting a matching IC socket too.

Joined Apr 22, 2010
22
I live in Australia, I will use what ever parts you recommend...thanks Bill

#### Wendy

Joined Mar 24, 2008
23,134
I haven't forgotten you. I've been playing around with the concept. Here's where I am at the moment. I'm likely to scrap this one, but it brings up a point.

The transistors Q3 and Q4 would be much better as logic level nMOSFETs. I need to know if you can get them.

CMOS 556 and a CMOS 555 is another part that would be nice to know if they are available in your area. If not I can adjust, but I need to know before I continue drawing.

The exact part numbers are not critical, if they match the verbal descriptions I gave above (CMOS 556, CMOS 555, and logic level nMOSFET) they would probably work.

#### Attachments

• 4.9 KB Views: 518
Last edited:

#### Wendy

Joined Mar 24, 2008
23,134
While I was about it I put designators on your diagram (which is very useful BTW). This will match to the LEDs in the schematic. You will need to learn enough to wire them in since the LEDs will have to have wires going to them from the PCB, no way around it. Since LEDs are polarity sensitive you going to have to learn which is + and - (or in electronics terms, anode and cathode). You can use two different colors of wire to keep track of them in the car.

The AAC text book has a section on LEDs here. Just scroll down until you find the section labeled LEDs. The illustrations should have all the information you need.

#### Attachments

• 8.2 KB Views: 598

Joined Apr 22, 2010
22
Hi Bill, how are you.?....Ok , I will find out about whether my electronics store stocks
CMOS 556, CMOS 555, and logic level nMOSFET.....tomorrow is a public holiday here (Anzac Day) so shops are closed, but Tuesday I will find out and I shall let you know Tuesday Night.
Regarding polarity of LED's, I have a vague idea, but I shall check the link you gave me and study up.
I really appreciate your time and help Bill, I sincerely do.
you have a great day, and I shall get back to you in 2 days time.

thanks mate.