Making A Jacob's Ladder - Danger & Fun Rolled Into One!

DIY time, let's make a Jacob's Ladder. Jacob's ladders were made popular back in the 50's & 60's being used as techy eye and sound catching props in science fiction and horror movies.

There's something intriguingly mesmerizing about watching and listening to that glowing electric arc of ionized air/plasma as it sizzles its way up the ladder, pops at the top, and then restarts the cycle over and over again.

A Jacobs ladder is educational and they are not that hard to build yourself for very little money; usually being under $100 if you purchase a used high voltage transformer or already have some of the parts on hand.

To get that cool classic movie "buzz" or "sizzle" electrical arc noise, old school high voltage 50/60Hz step-up transformers must be used. As shown in the video, oil furnace/boiler ignition transformers are great DIY options as most are rated at 10,000 Volts so enough voltage to self spark across an air gap. Oil burner ignition transformers are also low in cost, easy to find (both new and used) and fairly safe when given the respect they deserve / demand.

A few words on safety! HIGH VOLTAGE CAN KILL! If you're not comfortable working with and around the high voltages demonstrated in this Jacob's Ladder build video and don't understand the basic precautions of working with and around higher voltages, please don't attempt a build like this.
However, if you know & understand the basics and follow the required safety precautions, I think you'll find this a very fun, rewarding and entertaining DIY build project. You can make it as basic and easy or as complicated as you want.

I wanted my Jacobs build to have the flavor of a prop from the 50's or 60's, so I made a simple cube shaped enclosure with rounded edges from glossy black PLA plastic to give it the look of bakelite along with some shiny aluminum standoffs. An attractive wooden enclosure would look great and time period accurate too!

I never mentioned the top and bottom spark rod air gap distances on my Jacob's ladder in the video. This was intentional as it's going to be different depending on your transformer, the material your rods are made from and the thickness of the rods you use. There are also many variables in the air that will have an impact such as air movement, dust, humidity and temperature. Basically, anything that affects the ionization qualities of the air, are going to play a roll in the air gap distances of your rods. In short, you'll have to experiment.

With that said, here are the air gap distances of my rods to at least give you a starting point. My bottom air gap is about 5mm. The top of the rods I have spaced about 45mm apart which allows the spark to reach the very top of the ladder (24"/60cm of length) about 75% of the time if the air is dead still. Any air movement, and the arc will break sooner. Please experiment with gap distances to get the best results that you're after.

TIP: The rods slowly get carboned up during use and arc distance performance drops, so they must be kept clean if you want to maintain good arc qualities.

Time Chapters:
0:00 Introduction
1:00 The High Voltage Transformer
7:02 Standoffs & Rods For The Ladder
8:12 Testing Operation
9:26 Enclosure & Parts
11:46 Assembly
13:44 Completed Jacob's Ladder

Stuff Used In This Build:

Allanson Model 2721 10,000 V Ignition Transformers:
https://amzn.to/3NMqFyA

3D STL Print Files For This Jacob's Ladder Enclosure (Case & Lid):
https://www.e-junkie.com/i/1416f?card

1/2" Round Aluminum Bar Stock:
https://amzn.to/40tZrnX
or...
M5 Brass Standoffs:
https://amzn.to/4f4AOCX

Various Sizes of Stainless Rod:
https://amzn.to/4f7vxuq
or...
TIG Welding Rod:
https://amzn.to/3NO6C2S

C14 Power Receptacle:
https://amzn.to/3Yvd43E

DPST Toggle Switches:
https://amzn.to/40oGd30

120V LED Indicator Lights:
https://amzn.to/3C5pw2F

40KV High Voltage Wire:
https://amzn.to/48uaHCT

DISCLAIMER: This video is for information & entertainment purposes only! As with any electrical DIY project, you accept all risk and only you know if you have the required skills, tools and knowledge to perform such projects safely without hurting yourself or burning your house down!

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