stroboscope

[pepe sierra]

ok...so basically am planning to create a circuit which will create states of on and off .(probably using the ic 555)....and then...i'll use a relay to connect it to a switch that control the lighs of a room, so i can have an stroboscope effect........, so u just wanted to know how possible that is....

thanks

[pepe sierra]

i'll correct myself with that last sentence....., just in case

so I just wanted to know how possible that is

[Kain]

Hi. What sort of lamps are u planning to use? If you want to achieve a proper strobe effect u need to use discharge lamps like the ones used in photoflashes. Those have 3 electrodes - Anode Cathode and controlling electrode. The way it works is by applying high DC voltage between the Anode and Cathode and pulsing few kV voltage on the controlling electrode. Usually the voltage across the Anode and Cathode is delivered from a capacitor that is fully charged to the required working voltage. I have personally done some of those 5 years ago with 2 and more lamps. If you want to use a regular fillament lamps it will not work or it will be a poor effect because fillament lamps do not turn off fast enough (the wire inside is still hot and glowing) meaning that one can't switch them fast enough to achieve strobe effects well. Another thing is that flashing fillament lamps will kill them fairly fast.

[pepe sierra]

ok...so if i use photoflash bulbs i wont be able to use them with the ac povided from the outlet, right? or i guess i'll need to make a circuit to convert it to high dc, .

and i was planning to use fluorescent bulbs, not filament bulbs, so how well would that work? 

one more thing...can relays open and close , at high rates?...(5-20hz?)

ok..thanks again

[Kain]

You are right - you cannot use AC to power those up. However, one simple thing that you can do is voltage doubler or multiplier (depending on where you live). If your outlet AC is 220RMS then a doubler would do and of course you will need to limit the charge up current otherwise you might get more than just flashing  ;D. The problem with fluorescent bulbs is their intensity mostly. In fact, if you want to flash them fast you will still need high voltage to ensure that each pulse will break down the gas... I believe that there are relays that can open and close at this frequencies, but having in mind the current through its contacts when it closes I am sure its lifespan will be short overall. You can use SRC's or high voltage transistors instead, in combination with opto-couplers to insulate your pulse generator from the high voltage part of your circuit.

[EdwardM]

Hi

reference the relay switching rates, I once designed a system to play a sound organ and it used relays to fire each note, as I remember the switching time was in the order of 10-20ms, you just need search almost any electronic suppliers parts pages to get the details

Ed

[Kain]

Hi EdwardM!
True about the rates, but don't you think those contacts will not last with all this high discharge current and arcing? Considering they will be opening and closing from 5 to 20 times/s with all this arcing....oh well, just my thoughts  :)

[pepe sierra]

all right, thanks to all of u

[dito]

I need a strobe of leds with pulse __|-|_|-|_|-|__|-|_|-|_|-|__
traducing: interval, 3 shoots(on-off), interval, 3 shoots(on-off)...
I want to use the 555's, one in astable and other em mono-astable, but do know to make a circuit...

[audioguru]

Hi Dito,
Just make two 555 oscillators. The fast one pulses the LEDs and the slow one gates the fast one on and off by connecting its output to a voltage divider (to the positive supply) to provide a high enough voltage for the reset pin of the fast one.

I've made many LED "strobe" things that blink an ultra-bright LED 5 times quickly in 2/3rds of a second, then a 1/3rd of a second pause, over and over.
They drive 100mA pulses through the LED for only 45ms then a 90ms pause before the next pulse. The LED is off most of the time so the 100mA doesn't bother it.
Since the LED is off most of the time, and I used Cmos gates for the oscillators that draw an extremely low supply current, a 9V alkaline battery lasts for about 30 hours of continuous blinking. I used a 5V low-dropout voltage regulator so the brightness doesn't change as the battery runs down. To get 100mA pulses I used a small transistor driven from the oscillators.

They are blindingly bright! They light-up the houses across my street and reflective car licence plates far away. Most people buy my white and blue ones. I also have red and green ones.
One time I had 12 of them on the table making random patterns on the ceiling. ;D