Sound trigger for high speed flash photography, part 9

Some experiments with water filled balloons (about 100mL of water).  My niece was popping the balloons for me this time.  The SB-25 flash gun was set at 1/32 power.  The camera was set to f/10, ISO 200.

I am out of balloons now.  The dollar store is just down the street, but before I take any more balloon shots, I need to think about a different backdrop.

Balloon placed slightly on the side.  Notice the crown of water formed at the bottom.

Sound trigger for high speed flash photography, part 8

Another balloon pop.  I had the idea of popping it from the top.  The result looks like a cup.  For this capture, the balloon is positioned about 50cm from the microphone.  Flash output was set to 1/64.

Turqoise balloon pop.  Flash power set at 1/64.

Here is a shot of a yellow balloon popped from the bottom.  I was hoping to see something more interesting, like the shape of a parachute.  It still looks interesting with the ripples close to the edges.

Yellow balloon pop.  Flash output set at 1/64.

I had by mistake left the output power of the flash set at 100% on an earlier shot with a white balloon.  Flash output set at 100% lasts much longer than flash set to 1/64, but I don't understand the result.  Because the flash light lasts longer, one can see a ghostly shape of another balloon, but it does not explain why the balloon looks like it has not been popped.  My first attempt with a white balloon a few days ago also resulted in a shot of a full balloon.  I wonder if the white balloons collapse much slower than the colored balloons.  Strange.

White balloon pop.  Flash output set at 100%.

Sound trigger for high speed flash photography, part 7

I finally decided to draw the circuit I used for the sound trigger with the QUCS software.  Not all components are available in QUCS so I had to draw a couple of items in the schematic diagram.  These items have no electrical properties so simulation in QUCS does not work as is.

Note that the LM324 OpAmp is connected up with five pins instead of three as shown.  Pin 3 = positive input (reference signal), pin 2 = negative feedback, pin 1 = output, pin 4 = 5V input, pin 11 = ground.

Sound trigger circuit.  The capacitor polarity can be reversed?

Note also that the capacitor is a polarized capacitor, and the potentiometer is there to adjust the sensitivity of the circuit to sound.

Sound trigger for high speed flash photography, part 6

So, my hypothesis that sound traveled too slow was probably correct.  I decided to waste two more balloons tonight.  My first attempt was with a white balloon.

Notice in the first photo that the electret microphone was just about 20-25cm away from the balloon.  Here, when I popped the balloon, the flash gun fired off so quick that the shape of the balloon remained as a balloon.  I did make a mistake of puncturing the balloon from the backside.  It is possible that the rupture has opened a wide gaping hole that cannot be seen from this angle.

On my second attempt with a green balloon, it was more impressive.  It can clearly be seen that half of the balloon went missing.  This time around, I held the balloon a little further away from the microphone, about 40cm or so.  Half of the balloon was gone but it is also clear that the other half retained the shape of the balloon.  That is cool.

I think I need a couple of flash guns, or at least, I need to use a reflector to get more light on the right side of the balloon.

Well, this has been a good test.  Now, I know for sure the circuit is fast enough to capture a popping balloon.  I just need to play a bit with the light now.

I have a wild idea of shooting firecrackers.  Darn, the Lunar New Year just passed.  Hmm... I think I have to wait until Canada Day.

Sound trigger for high speed flash photography, part 5

So, it's easier said than done.  My balloon pop test shows that my circuit is too slow or that sound does not travel fast enough--the microphone was positioned about 2.5 metres away.  The flash gun was positioned about a metre away.

Let's see.  Sound travels at 340 m/s.  To cover a distance of 2.5m, it would take 0.0074s or 7.4 ms.  Maybe the balloon collapses faster than that?

Well, I just wasted one blue balloon.  Fourteen more to go.

Blue balloon pop

Sound trigger for high speed flash photography, part 4

My fingers were itchy.  I wanted to find out how good the sound trigger really is.  My first attempt with the flash gun did not work too well.  The flash fires off only with a really loud hand clap or an air blow onto the electret microphone.  I had to replace the PN2222A transistor I used with the OptoIsolator I used with the laser trigger circuit--it looks like, although I am not sure why, the Base of the PN2222A may need to be driven by at least 3.8 volts or higher current but the circuit could muster only 2.5 volts or so and about 3 mA, but about 2.5 volts is enough to activate the OptoIsolator.  With the OptoIsolator, a finger snap can trigger the flash gun to fire.  After I got the flash to fire, it was time to look for some target to shoot.

I remember seeing a couple of bags of balloons at my place a few years ago but cannot find them anymore.  Perhaps they were used up for weddings and birthday parties.  Balloons would be really cool I think, but there was none around.  I had nothing cool to test the sound trigger with.  I decided to test with a marble and a column of Mega Blok blocks.  I am unimpressed with the capture but it shows how good the sound trigger worked.

The marble hits the column of Mega Bloks pretty hard--I used to play with marbles and a flicker of the thumb sends the marble off pretty fast and hard.  One can see in the photo below where the column broke and how the top half stayed fixed while the bottom half started to move by a millimeter or so.  So, the sound trigger worked quite well.

Marble and Mega Bloks

I think the Dollar Store sells those balloons.  If I have time tomorrow, I will grab a few balloons to try out.

Laser trigger for high speed flash photography, post-final

I adjusted the circuit a tiny bit. I added an LED and another potentiometer after ORgate1.  This works really well.  The additional 1 KOhm potentiometer allows for fine tuning of the resistance (and therefore the trigger delay).  The LED prevents current from the DelayCapacitor when it discharges (when the circuit gets reset) from flowing back towards ORgate1.  A regular diode should really be used instead of an LED as voltage drops significantly across an LED (but for my purpose, the LED works and I do not have any regular diode around.)

Description:

• CircuitResetSwitch:  when the switch is closed, it will cause the DelayCapacitor to discharge quickly to ground, and it will cause XOR_OnOff to output a zero voltage.  The CircuitResetSwitch is implemented with a MOM (momentary) switch.
• OptoIsolator:  triggers the flash to pop when a trigger voltage is reached, and protects the circuit from a possibly high current from the flash.
• PhotoResistor:  when a strong source of light (i.e. the laser) hits it, its resistance goes down to 10 Ohms, directing most current to ground.  If the source of light is broken, its resistance goes up to 1 MOhm, directing most current to ORgate1.

Actual implementation:

Breadboard, laser pointer, and lego water dispenser

Components on breadboard

Breadboard on another angle

Breadboard from another angle

Water bodies, part 4

I could not capture a water crown so the next best would be a Budweiser.  I think their commercial has a upside down cap on top of the bottle.

Evaporation

Boring

Group shot

Fist

Single

Waste

Red blob

Peek-a-boo

Thinker

Shark fin

Fizzle

Yum

Dance

Planets in orbit

Refreshing

Grow

Tipped

Explosion

Water bodies, part 3

My next attempts were to capture a water crown but so far no go.  Perhaps I need some liquid with higher density?

What I got yesterday were still similar to the other shots I have already taken:

Maybe the formation of a crown?

Planet and vortex

UFO

Cone

Bean

Another formation of a crown?

Water bodies, part 2

So, I did decide to go back to using my laser setup.  This time around, there were two things I did differently than the last shoot.  For one, I am operating in relatively bright room light, and second, I built a Lego (well, I am using Mega Bloks actually) bridge with a water dispensing head (see below).  The light allows me to see what the heck I am doing and the bridge focuses the water drop in one location so I can break the laser beam most of the time.

Anyhow, I am satisfied that the laser setup works well.  Here are some more photos:

Standard finger

Volcano

Weird slanted projection

Weird crook

Another finger

Tower

My setup with the Lego bridge with the water dispenser, the laser pointer powered by 3 AAA batteries housed inside a digital alarm clock, the laser trigger circuit, and the SB-25 flash gun.