Question for electronics whizzes

[thething84]

right. basically i wanna make the police type lights. I can remeber making one many years ago.

I have a circuit which uses two 2n3096 transisters.

the problem i have is that it just isn't working, and when i do get it to flash its so dim that u can hardly see it. any help, muchlyappreciated.
it is the
the right cicuit (http://www.reprise.com/host/circuits/transistor_flasher.asp) right. basically i wanna make the police type lights. I can remeber making one many years ago.

I have a circuit which uses two 2n3096 transisters.

the problem i have is that it just isn't working, and when i do get it to flash its so dim that u can hardly see it. any help, muchlyappreciated.

[patmat2350]

Only guessing, but:
a) different LEDs can require different resistors (need more or less current) to get their full brightness;
b) Are you looking at your LEDs from the side? They're VERY directional, like little spotlights... view straight on, quite bright, from the side, nuthin. That's why I don't care for them for general lighting projects.

Pat M

[RGinCanada]

I have a circuit which uses two 2n3096 transisters.
Like patmat said play with resistors. The 470 ohm resistors for the brightness, and the 39k resistor and the 10uF capacitor for the flash on/off duration.

They're VERY directional, like little spotlights... view straight on, quite bright, from the side, nuthin
Wandering a little off-topic...

Pat, have you tried putting a dab of silver paint on the tip of the LED, and roughing up the sides with 220 grit sandpaper? It makes them into more of a diffused light. I use LEDs because they last forever, and all my lighting is more-or-less permanently mounted.

[patmat2350]

No, but I'll be sure to! I can't stand the idea of building a bunch of GOW bulbs permanently into a complex mast structure or such, knowing they can burn out some day.

PM

[thething84]

yeh i know about the leds. but it doesn't appear to flash at all. they stay constant now. and the only time they flash is if i take out the 39k resistors.

[viking57]

Thing, try this site it my have something for youelectronic projects for rc (uoguelph.ca/~antoon/gadgets/gadgets.htm) cheers! john edit; link wont work type this uoguelph.ca/~antoon/gadgets/gadgets.htm

[Umi_Ryuzuki]

We picked up some selectable flash bicycle blinkers. Tachikaze says, "Their cool".
He keeps forgeting to bring them up and show me, but he says they will do a pretty good imitation of emergency vehicle flashers. We just have to pick what color LED to put to them.

Definitely play with the lower value resistors at the 470 ohm location.
The 470 ohm resistors determine the LED brightness. Lower resistance means higher current, and more light. LEDs that require more current or have a higher operating voltage (such as green and yellow) may work better with 300 ohms.

While we are at it, anyone know of a counting circuit that once switched on, will count 5-10 seconds and then turn on an LED, or relay? I have more project Ideas,...
Like I need more projects...

[RGinCanada]

a counting circuit that once switched on, will count 5-10 seconds and then turn on an LED, or relay

The '555' timer chip can run in "one shot" mode and will do this nicely for you. If you need a circuit diagram, let me know and I'll spray some WD-40 in my ear to loosen up the rust upstairs, and scribble something out.

[thething84]

well as regard to the resistor. on the one where i got it to flash correctly by taking the smalled resistor out alltogether. i tried it with no resistor before the led and it never changed brightness. i have noe reason why this circuit doesn't work.

[thething84]

i may try making another type using two logic gates. but that means i gotta make the logic gates. unless ya can buy them premade.

[Umi_Ryuzuki]

The '555' timer chip can run in "one shot" mode and will do this nicely for you. If you need a circuit diagram, let me know and I'll spray some WD-40 in my ear to loosen up the rust upstairs, and scribble something out.

A scribble would be very helpful. ;)

[AmokCrow]

RGinCanada

Why use a chip in the first place, wouldn't a capasitor with the right resistor with a transistor swithc do the same more simply and be less sensitive to rough handling etc.?

-Michael

[AmokCrow]

Like so.

R1: 100k
R2: 1k
R3: 0-10k (changes time before "on")
Capasitor: some 1000yF

Hope it works.

As for the police lights I'd recommend using a Future Kit series kit. They got just what you need for $1,5.

-Michael

[Umi_Ryuzuki]

Like so.

R1: 100k
R2: 1k
R3: 0-10k (changes time before "on")
Capasitor: some 1000yF

Hope it works.

As for the police lights I'd recommend using a Future Kit series kit. They got just what you need for $1,5.

-Michael

Michael,

I will try building one of these and see how it does...
I could put a pot into R3 and make it variable then couldn't I?

Thanks.


Umi

[AmokCrow]

Umi

Yes, a potentiometer would be preferable.
Also note that counting starts when switch in schematic is released.
I'd recommend starting adjustment of timer from lowest potentiometer setting to save nerves and time.

-Michael

[Umi_Ryuzuki]

Umi

Yes, a potentiometer would be preferable.
Also note that counting starts when switch in schematic is released.
I'd recommend starting adjustment of timer from lowest potentiometer setting to save nerves and time.

-Michael

When the switch is released?
So push the switch, release, start the count?

So if I wire to the normally closed contacts of the switch, when I push and hold the switch it will count? I kind of want it to work this way, and if you let go of the switch, it will reset, and you have to start the count over again.
The challenge will be to hold the switch down once you contact it. Otherwise you have to begin again.
(yeah, I know everyone is beginnging to wonder now.. :rolleyes: )

:p
Umi