TSP #3 - Camera Flash Circuit and Nixie Tube Tutorial (Part 1/3)

In this episode (Part 1/3) Shahriar explores the principle operation of a camera flash circuit. The flash circuit is analyzed at the schematic level and through measurements. He then moves on to power a nixie tube using this circuit and calculates the efficiency of the DC-DC converter for this type of application. There is also a little quiz in this episode! Whoever solves the quiz will chose the topic of the next video.

>> Hi, welcome to the sigma path.

Since the last episode,

I received a lot of messages from you guys about a type of episodes you like to see,

and we have a lot of exciting topics to cover in the future.

A lot of equipment review,

a lot of component review.

A lot hacking, and today's episode is also for you hackers out there.

We'd like to see if you can combine this disposable camera,

and this Nixie tube. Well, specifically the flash circuit inside disposable camera,

and the process we're going to learn exactly how

that flash circuit works at the schematic level,

and also using some measurements.

We are also going to take a little bit look at these Nixie tubes.

So let's get started with this,

and see what I'm talking about here.

You can get these at pretty much any convenience store or any big supermarket.

What is special about these thing is that,

this particular model has a built-in flash,

so that's you're looking for.

If you're going some places that developed the film for these things, they may

give you a used band for free since really they just recycled them.

They throw them away. So what we're going to do is,

we're going to take this apart.

Take the circuit that we want out of it, analyze the circuit,

and at the same time see if we can use that circuit to somehow power the Nixie tube.

So, it will be an interesting combination.

Am not sure if anyone's ever done that before,

but there's a lot of cool things that people have done

using these disposable flash cameras because there's

a high voltage DC-DC converter that is inside of it,

and of course a very big capacitor.

So we're going to take one of these apart,

and let's take a look and see what's inside it.

Will look at a circuit, and we'll go from there.

Okay, here we have a disposable camera with a flash built-in.

Before we take this apart I have to warn

you that you should only do this at home if you have

experience with high voltage circuits

because even if the camera hasn't been used for a while,

the capacitor inside may hold enough charge to give you a nasty shock.

So never do this unless you have experience with this type of circuits.

These type of cameras are all housed inside a paper containers.

This is done because they want to be able to

take this apart very quickly, and take the film out.

So I've already taken this apart so we can throw that away.

The top and the bottom are held together using these little plastic pins.

So you can put a screwdriver on and shift,

and then we can take that off.

So I've done that also.

So you can take the top cover off,

and we can throw that away.

So if you look inside the camera,

we can right away see this large double A battery.

Large with respect to the rest of the circuit,

and you should always keep these even if you're not

interested in the circuit itself because once the camera's used up,

and you are about to throw it away or give it away.

These guys usually still have enough charge in them to be

useful for something else maybe a remote control for example.

So don't throw these away or if you do,

make sure you recycle them.

So here's a double A battery that powers the flash.

Here's a flash circuit itself.

This entire PCB is only responsible for operating the fly circuit.

At the top, you can see these little metallic pin.

This metallic piece here is actually the "On" and "Off" button of the flash.

There's a plastic button on the outside.

When you press down, everything comes down and

connects the two paths that are right underneath it,

and that closes the circuit,

and turns the flash on.

On the front side of the camera,

you can see that big capacitor I was telling you about.

This capacitor is what holds the charge for the flash.

There is the flash unit, the flash tube itself at the top,

and there is a little LED.

This one's actually equipped with a little LED that shows you,

tells you when the flash is charged,

and ready to be fired.

Interestingly enough, I took apart another identical camera,

and that one had a neon lamp inside.

So we'll talk a little bit about that when we analyzing the circuit.

So let's try, and run this flash once,

and fire it, and see how it works.

Again, so we have to be very, very careful here.

So here's the "On" and "Off" button,

and there's also two pieces of wire,

two piece of metal here,

and these two pieces of metal are the mechanism that fires the flash itself.

When you push the shutter button, a little lever comes down

and briefly touches these two pins together,

and I think that's the lever right here.

This thing comes down right there,

and touches those two pins together.

When that happens, that's when the flash actually is fired.

So we can charge it,

and then I will manually do that so we can see the flash go off once.

So I will push this down and you will hear

that characteristic noise that you hear when the flash is being charged,

and we'll talk about why that is later on. So here we go.

So I can hear it charging.

So I can see that the LED is turned on meaning that flash is fully charged,

and ready to be fire.

So I'm going to let go of the button.

I'm going to connect those two wires that I told you together a very briefly,

and we can see the flash go off. There it is.

So even as the flash went off, the capacitor is not

fully discharged, so there is enough charge in there to give you a shock.

You have to be very careful.

So I'm going to discharge the capacitor first using a metallic piece.

Take the battery out, and then take the flash circuit out.

So let us take the battery out first.

Put that aside, and I can see the two terminals of the big capacitor at the top.

You can see them right there.

That's the first terminal, and that's the second one there.

So I'm going to use a screwdriver,

and discharge that capacitor before we move forward.

Okay. I went ahead and discharge the capacitor of the camera.

I will show you a complete discharge using that method.

It's just fun to do later on during the video.

So, you can take a flash circuit out by moving this pin on the side.

So let me do that, and here we go.

So the flash circuit comes right out.

It's one single unit. We don't need this.

We can throw the rest of this out,

and let's take a close look at this,

and see what components are involved in making one of these,

and then we will analyze a circuit.

So of course, from the back you can see that flash tube,

and you can see the two terminals of the battery,

and the little terminal here that does the firing of the flash itself,

and in the front we can see that the entire circuit uses only one transistor.

So there is one transistor.

There's one diode.

There's three resistors.

One little in here.

I hope you can see this on camera.

There's one there, and there's one resistor right there.

There is a big transformer here,

and a little transformer on this side,

right here, and there is another capacitor up here, and a big one here.

This big this is electrolytic capacitor,

that's capacitor that keeps the charge for the flash,

and this is an aluminum foil capacitor here that is for a slightly different function,

so I'll tell you about that later,

and this transformer has a top connection.

This top connection from this transformer goes directly to the center top of the flash,

and these two connectors of the capacitor go to the other two sides of the flash,

and we will take a look at that, too.

So, what I've done is that I've taken this,

and I have drawn a full schematic of it,

and we would like to find out how this works.

So there's going to be a little bit of theoretical stuff there,

and then we will see what we can do with it.