Piezoelectric igniter crystal from a BBQ lighter

Many barbeque lighters use a piezoelectric crystal to create a spark to ignite a gas such as butane. When the crystal is used in this way it is often refered to as a piezoelectric igniter. The source of the gas is contained within the lighter body. If you remove this piezoelectric crystal while keeping the trigger mechanism and wires attached, you can see that it creates a spark around 7mm in length. This is in the kilovolt range.

Getting a crystal from a BBQ lighter

I needed such a crystal so I purchased one of these lighters and removed it as the following pictures show. Care must be taken in taking it apart since there is a flamable liquid under pressure here. I first kept lighting the lighter until it wouldn't light anymore in order to decrease this pressure. Note that this decreased the amount of fluid by only half so care must still be taken after this point.

The lighter. Note that this has been reassembled for purposes of taking this picture but without the trigger. But this illustrates what you should look for in the stores.

Here it is after disassembly (trigger and crystal not shown, see pictures below for these). You basically pull off the long black part. Then you pull off the shorter black part. The part with the flamable liquid is on the right. You have to CAREFULLY cut this away while splitting the remaining body part as the picture below shows.

Here is it with the body split apart. At this stage you can remove the trigger and crystal.

The trigger and crystal. At this point you can hold the ends of the wires about 7mm apart and work the trigger. When you do, you'll see a part between the wire ends. If you don't get a spark then you're probably shorting the wires with your fingers where you're holding on to the crystal. Move your fingers away from the wires.

The crystal is the light olive colored part that the wires connect to. In the Testing section below you can see the crystal.

Testing the crystal

I didn't make any measurements or take pictures with the kilovolt spark. However, having extracted the crystal, I did some simple measurements hitting it in other ways.

Actually, the crystal is a cylinder embedded in the rectangular plastic and epoxy body so you never see it. On one end is a small metal ball. This is the end you hit. The pressure is applied on the same axis as the polarity. Here I'm flicking it with my fingernail.

This is the resulting 4.16 volts as a result of the flick with my fingernail.

Here I'm hitting it against the table top.

This is the resulting 240 volts as a result of hitting it against the table top. Note that I've seen voltages as high as 500 volts, the highest my oscilloscope will show.

Video - How to get a Piezoelectric Crystal from a BBQ Lighter

Here's a step-by-step video I made of another BBQ lighter I took apart. This crystal is cylindrical and wired a bit differently.

Piezoelectric static electricity generator

You can turn your igniter into a piezoelectric static electricity generator. Here I show how I did that using the ignitor from the above video. It's easy enough to make it give a shock during the instant that you press the trigger, but the idea here was to build up a charge on an attached metal ball (see photo below) by pressing the trigger repeatably, which turns out to be tricky. You'd think you could just attach a ball to the end, but the instant you release the trigger the charge is lost.

The BBQ ignitor I used.

The finished electrostatic generator.

To make it, the ignitor is shortened (see photos below.) A piece of plastic then extends out the end to support a metal ball. The metal ball is electrically isolated from everything else.

The wire that went from one end of the piezoelectric crystal to the tip of the ignitor is lengthened and made to be one end of a spark gap facing the ball (red wire in the photos below.)

Then a piece of aluminum foil is draped over the outside of one half of a ping pong ball and grounded by being connected to the other side of the piezoelectric crystal, which is also attached to the ignitor's silver case, hence the term grounded (see below.)

To charge it, the grounded foil is brought near the metal ball. Note that the half plastic ping pong ball acts as an electrical insulator, preventing the foil from electrically contacting the metal ball. Instead, each time the ignitor is triggered, a spark crosses the spark gap from the red wire to the metal ball. It's held on the ball during the spark by the attraction from the foil, since the red wire and the foil are connected to opposite sides of the piezoelectric crystal.

To get the ball to act as an isolated charged object, the foil is moved away, in this case by a plastic lever mechanism. When the ball is brought near the terminal of an electroscope, the electroscope's leafs separate, indicating that the metal ball is now charged.

Charging the ball.

Testing using an electroscope.

Other piezoelectricity explorations