(Wasn't it great learning in an age before cars had seatbelts, before push mowers had kill bars, and when nothing had warning labels?)

I was mostly tongue in cheek about the danger above, as the most dangerous step would be relieving a previously functional CRT of the transformer block. The CRT discharge can kill you.

Using an ignition coil should work (I didn't try it) and is likely safer to source if you're getting it from something assembled instead of from a used parts bin.

As for the rest of the owl, this is from memory, nearly half a century ago, so, yeah, disclaimers:

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# How to Build a Prank Shock Box for a Science Exhibit

This fun project will surprise your friends with a harmless electric shock when they pick up a prank box to guess its weight. Here’s how you can build it and how it works.

## Materials:

- 9-volt battery

- Step-up transformer (designed to increase voltage)

\_ consider a flyback transformer from old CRT or auto ignition coil, talk to circuit electrician expert

- Switch (spring-loaded or pressure-based)

- Wires

- Small box (to hold the circuit)

- Electrical tape

- Conductive foil or metal strips for accessible sides of box

## How It Works:

This circuit uses a step-up transformer coil to generate a small electric shock when someone picks up the box. While transformers typically work with alternating current (AC), here you use direct current (DC) from the 9-volt battery. The trick happens when the circuit opens as the box is lifted, causing the transformer’s magnetic field to collapse and induce a voltage spike.

When the box is lifted, the switch opens, cutting off the current from the battery. This sudden interruption collapses the transformer’s magnetic field, generating a quick, harmless jolt.

## Steps to Build:

1. Assemble the Circuit:

- Connect the 9-volt battery to the primary side of the transformer, with a switch in between. The switch should stay closed when the box is at rest and open when it’s picked up.

- Wire the secondary side of the transformer to two sets of exposed contact points on the outside of the box: one set connected to the positive side and the other set to the negative side of the transformer.

2. Add Conductive Surfaces:

- To make it more effective, cover three sides or faces of the box with conductive material (like aluminum foil or metal strips) connected to the positive output of the transformer. Then cover the opposite three sides with conductive material connected to the negative output of the transformer.

- When someone picks up the box, their hands will naturally touch both a positive and negative side, allowing the shock to pass through them.

3. Install the Switch:

- Position the switch on the underside of the box so that it opens when the box is lifted. You can use a spring-loaded or pressure-based switch that triggers when the box is moved.

4. Test the Circuit:

- With the box resting, the current will flow through the transformer, building up a magnetic field. Once someone lifts the box, the circuit breaks, causing the field to collapse and induce the shock.

5. Secure the Box:

- Place and affix all the components securely inside the box, bringing your two wires through the sides and making sure the exposed contact points are positioned on opposite sides of the box. Tape down any loose wires.

## Science Explanation:

This project uses Faraday’s Law of Induction, which states that a changing magnetic field induces voltage. The transformer converts the collapsing magnetic field into a brief, high-voltage spike, delivering a small shock to whatever is completing the high side circuit when the low side circuit is opened. Although transformers usually work with AC, you’re using the moment when the DC current stops to mimic that effect.

https://en.wikipedia.org/wiki/Faraday%27s_law_of_induction

The conductive material on the box ensures that when someone lifts the box, their hands make contact with both the positive and negative sides, completing the circuit for the jolt.

## Safety Note:

When done correctly, this project delivers a tiny, harmless jolt, similar to static electricity. Always use low power, an appropriate transformer, and avoid using higher voltages or currents. Consult with a TV repair expert or similar on your design before starting. DO NOT TOUCH ASSEMBLED CRTs. Let the TV repair person do it. She'll have parts anyway.