Flashing Police Lights

[parkaroo13]

I have two 12 volt lights that came from an old police car. Does anyone have a simple way to wire the two of them up to make them flash again? Right now I have them wired to individual push button switches, but I would like to make them flash on their own.

Also I have a Police strobe light (Whelen 02-0361112-00) with red, black, and white wires where the white white wire leads through a circuit and to the bulb. Does anyone know how to make this work as well? Do I need some sort of control module or can i just use simple switches and power supply?

Thanks,
PG

 

[colin55]

Here is the circuit you need. It is called BREAKDOWN BEACON


**broken link removed**

<snip: spam>

 

[Andy1845c]

Hi PG, there are many ways to mack your 12v lights flash on their own. The circuit colin55 posted will make them alternate left/right. If the lights you have draw alot of current, you may have to modify it a bit.

The strobe light will require a high voltage power supply and a way to trigger the tube to control the flash pattern. Many commercial made strobe light power supplys will take care of both.

Please note that putting flashing lights on cars in not legal in most countrys.

 

[colin55]

What do you mean by: "there are many ways to make your 12v lights flash ON THEIR OWN." How can globes: "flash ON THEIR OWN?"

What do you mean by: 'If the lights you have draw alot of current, you may have to modify it a bit."

The BD679 darlington transistors deliver 4A with a peak of 7A and this is adequate for the application. We have sold thousands of kits for $5.00 inclung parts and PC board, so I don't know what you are talking about.

Colin Mitchell

 

[Andy1845c]

Geez, calm down a bit.

He said he was using a seperate push buttons to flash them. Your circuit will makes them flash without having to sit there pushing buttons. By "on thier own", I mean with no human interaction.

He didn't say what kind of pattern he wants. Yours will do single flash left/right. If he wants double or quad flashes, or something else, a differnt circuit will be needed. If he wants both to flash at the same time, or dosn't care about a symetrical pattern, a 12v turn signal flasher or two will do the trick.

He dosn't state exactly what kind of lights these are. They might be little dash lights that draw hardly anything or rooftop lights that draw several amps.

I didn't look up the datasheet for the BD679 before I posted. After reviewing it, I would doubt that his lights draw over 4 amps, but I don't know. From his post, neither do you.

 

[colin55]

You must make the circuit very "tight" otherwise it will not oscillate. This requires the leads to be thick and the wiring to be as short as possible. This is due to the very high "cold current" of the globes - 6 to 10 times the operating current.

 

[chemelec]

This "SCR" circuit works good for Alternating Flashing lights, Even car Headlights:

**broken link removed**

 

[Hero999]

What about replacing them with high power LEDs?

Three 700mA blue LEDs in series with a suitably sized series resistor aught to do it. Because they're driven at 50% duty cycle, you can also drive them at a slightly higher current than their rating to increase their brightness.

 

[Boncuk]

How about making them flash like Chuck Norris' flashing headlights in his "police car"?

Look really frightening!

Use a timer circuit connected to a decimal counter and drive the power transistors using a diode network.

Something like that:

Lights double flash alternating at a rate of approximately 20Hz. The MosFet power transistors don't require cooling if the load doesn't exceed 3A.

Cheers

Boncuk

 

[Ubergeek63]

How about making them flash like Chuck Norris' flashing headlights in his "police car"?

Look really frightening!

Use a timer circuit connected to a decimal counter and drive the power transistors using a diode network.

Something like that:

Lights double flash alternating at a rate of approximately 20Hz. The MosFet power transistors don't require cooling if the load doesn't exceed 3A.

Cheers

Boncuk

It would be more frightening if it were his eyes flashing!

 

[Boncuk]

It would be more frightening if it were his eyes flashing!

They do!

 

[parkaroo13]

How about making them flash like Chuck Norris' flashing headlights in his "police car"?

Look really frightening!

Use a timer circuit connected to a decimal counter and drive the power transistors using a diode network.

Something like that:

Lights double flash alternating at a rate of approximately 20Hz. The MosFet power transistors don't require cooling if the load doesn't exceed 3A.

Cheers

Boncuk

This is the type of design I would really like to use. The only problem is I'm not too good with schematics. Is there a parts list for this circuit somewhere?

 

[Andy1845c]

What did Chuck Norris' flashing headlights look like? I don't remember them from the show. '

I am pretty sure U1 in Boncuk's schematic is a 555 timer. Its very common and easy to get. U2 looks like a 4017 Decade Counter. Also very common and easy to find.

The BUZ10's are power MOSFETs. The resistors and capacitors have values next to them.

The 555 is used in astable mode. If you google "555 astable" you will get lots of pages to learn about how this works and how to adjust the speed.

The 4017 just clicks along at the speed the 555 is going, setting one pin at a time high. Pretty much

Pulse 1 from the 555 sets Q0 high and lights lamp A
pulse 2 will make Q1 go high and Q0 go back low. Nothing is hooked to Q1 so lamp A goes out
pulse 3 makes Q2 high and lamp A goes back on
then we have 2 unused pins that give a delay and then we move over to lamp B and repeat.

Q8 is hooked to the reset pin on the 4017 so we can do it all over again. This just loops over and over and over.

Make sense? The diodes block the current from going back to the low pin on the 4017

The speed of 20Hz seems way to fast for a incadesent bulb to me. I don't think it will even flash at that speed, just look steady and a bit dim.

I am sure Boncuk will stop back in and clarify this in time. He's a regular around here.

 

[Hero999]

How about making them flash like Chuck Norris' flashing headlights in his "police car"?

Look really frightening!

Use a timer circuit connected to a decimal counter and drive the power transistors using a diode network.

Something like that:

Lights double flash alternating at a rate of approximately 20Hz. The MosFet power transistors don't require cooling if the load doesn't exceed 3A.

Cheers

Boncuk

That won't work.

Both MOSFETs will stay on because the LEDs (which won't light) prevent the gat capacitance from being discharged when the IC's outputs go low.

It looks a bit too complicated. I'd just use a couple of NANDs connected as an astable driving a pair of MOSFETs via another couple of NANDs acting as a buffer. I'd use a cheap CMOS quad NAND such as the CD4011.

 

[Andy1845c]

That won't work.

Both MOSFETs will stay on because the LEDs (which won't light) prevent the gat capacitance from being discharged when the IC's outputs go low.

Would this also hold true if he has incandescent bulbs in his lights? I kinda doubt they are LED lights, but then again I have no idea.

 

[parkaroo13]

The lights I am using do have incandescent bulbs. I just purchased all the parts yesterday but have not soldered them yet, so if I need to return them I still can.

 

[Andy1845c]

What circuit did you buy parts for? Boncuk's?

Hero999 definatly knows more then me, but I don't see why the MOSFETs won't work with incandescent light bulbs.

Do you have a protoboard or a way to build it and test it without soldering?

 

[parkaroo13]

Yes, I chose the "Chuck Norris" circuit lol. I unfortunately don't have any way of putting it together without soldering. I have to wait until the end of the week to put it together anyways, so I'll just wait to see if anyone can find problems with it.

 

[Hero999]

What circuit did you buy parts for? Boncuk's?

Hero999 definatly knows more then me, but I don't see why the MOSFETs won't work with incandescent light bulbs.

It's got nothing to do with the incandescents.

The LEDs he added in series with the MOSFET's gates prevent their capacitances from discharging.

If the frequency is low enough then this might not matter since the diode leakage current might discharge the capacitance there again it might not so the MOSFETs will never turn completely off.

The LEDs will also never light, well the may light for a couple of µs when it's first started but you woudnn't see that.

I think he forgot that MOSFETs have a high impdance capacitive gat and need a push-pull driver. If the MOSFETs were replaced with BJTs then it should work fine.

 

[Andy1845c]

The LEDs he added in series with the MOSFET's gates prevent their capacitances from discharging.

Aren't those just regular diodes? Maybe this dosn't even matter as an LED is also a diode?

I am in a curious mood. Is there a way to make this circuit work with the MOSFETs?

I am guessing the 4017 dosn't like voltage on a pin that is in the low state and thats why he has the diodes on series with the gates?

You couldn't simply add a pull down resistor on the gates of the MOSFETs could you?

I'm just throwing stuff out there for the sake of my own understanding. Sorry if I am missing the point completly. lol