Knight Rider with Halogen Bulb

[Captain Nguyen]

Hi,

I'm new here, and come from holland.

I have one problem.
I have made my Knight Rider Scanner with PIC16F628.

Only LED will work, but no halogenbulb.

I have tried with this schematic.

[windoze killa]

try replacing the TIP32 with a relay. Another option, replace the 1K resistor with a 470R. This would turn the TIP32 on harder. But I think the relay would be the best shot.

[Captain Nguyen]

oh,

I have wrong.
It's Tip42, not Tip32. ::)

And it's for car.
With relay hear you all the time when it on. :o
It would not like it.

And this schematic from http://ratliff7.tripod.com/counsel.htm would not work best.


I have hear from other forum.
They say it does not work best, It would very heat.

So, how dit they do that?
Like as Knight-f2k4 scanner.

And could this work at first schematic?
http://www.electronics-lab.com/forum/index.php?topic=2373.0

[audioguru]

Look at the spec's of the transistors to see why it doesn't work.
The halogen bulb draws more than 4A when hot, much more when cold.
The TIP42 and most other power transistors need at least 400mA of base current to saturate with a 4A load and has a min current gain of only 12 at 4A.
The 1k base resistor allows only about 11mA of base current. A 27 ohm base resistor would give the output transistor enough base current but its 400mA is much too high for the BC547. A 2N4401 transistor can replace the BC547 and the 10k resistor must be replaced by a 390 ohm resistor for enough base current.

Your last posted schematic has the TIP31C upside-down.

[Captain Nguyen]

Like as this?

Or must I replace from Tip41 to Tip32?

[audioguru]

Your new circuit is correct. Add a 1k resistor to quickly turn off the TIP42.

[Captain Nguyen]

Thank you,

And resistor of 27 ohm.
Is it 1/4 watt or 1/2 watt?

[audioguru]

And resistor of 27 ohm.
Is it 1/4 watt or 1/2 watt?

It will ocasionally have about 11V across it. So its momentary dissipation is 11V squared/27 ohms= 4.5W. The percentage of the total time that it is turned on determines its average dissipation. 1W? 2W?

[Captain Nguyen]

Okay, I will use 1 W resistor.

[MP]

I have to agree with Windoze,
I don't like to add power transistors to car circuits. Especially where there will be multiple sets of this circuit.
The Emergency Response agencies have already figured this all out. They use lots of blinking bright lights. They use relays to make these blink. If you do not want to use a relay that will click and has a short life, use a Solid State Relay for this. There will be longer life and less waste. They will cost you more than a TIP32, but reliability will be built in. I have made several devices over the years that use solid state relays. Some are still used in an Industrial environment for better than 20 years.

MP

[Captain Nguyen]

Thanks for info.

And it work now with tip32.
I did not use always.
Only for show at meeting or friends.

[wuemura]

I wonder if this same effect could be made with a 4017 with some electrolitics capacitors at the output to make that flash trail behind or some delay when the light change from one channel to another.

[audioguru]

I wonder if this same effect could be made with a 4017 with some electrolitics capacitors at the output to make that flash trail behind or some delay when the light change from one channel to another.

But a "flash trail" means that the output transistor will be operating as a linear amplifier and getting very hot. You could do it with PWM and it would remain cool.

[Captain Nguyen]

I use with PIC16F628.

But I must learn how write pwm effect in Jal.

[audioguru]

But I must learn how write pwm effect in Jal.

Hee, hee.  ;D
When do they let you out of jail?

[wuemura]

But a "flash trail" means that the output transistor will be operating as a linear amplifier and getting very hot. You could do it with PWM and it would remain cool.

No, no,  no, what  meant to say was to make the same effects with 4017 and LED's ;)

[Captain Nguyen]

Hee, hee.

[audioguru]

No, no,

[Captain Nguyen]

Your new circuit is correct. Add a 1k resistor to quickly turn off the TIP42.

Long time ago yes.

But with 1K resistor will it quicly turn of?, and without?
Slow to off?

[audioguru]

Transistors should always have a resistor or circuit between their base and emitter to turn them off. Without anything, then heat or a nearby radio transmission will turn them on or keep them on.

[MP]

There are many applications where a resistor between base and emitter is not needed on a transistor.
"Always" is certainly an exaggeration.
Also note, protection from radio waves requires filtering. A resistor does not protect against radio interference.

MP

[audioguru]

There are many applications where a resistor between base and emitter is not needed on a transistor.

Darlington transistors also have a resistor between base and emitter.

[MP]

Darlington transistors also have a resistor between base and emitter.

Not always. They are used both ways...which is another example of situations that do not require this resistor.

MP

[Captain Nguyen]

Schematic works  ;D 8)

[wuemura]

Schematic works  ;D 8)

Nice, i will make the same effect but for a break light for my car with very bright led's, but i will change some things to look like a normal break light (all led's on) and than after some time knight rider effect, you see here at Brazil we can't use any light effects outside the car, like flashes etc. Only Police, fire fighters, ambulance can use such a things.