Spark Gap Transmitter

[BlackGT97]

Hey,
Some of you may have seen the t.v. show "The colony". The stuff this guy comes up with confuses me. So i decided to join this forum in hopes for some answers. I will make several threads refering to differnet inventions from different episodes.

The fist one I have is the spark gap transmitter. I get the concept of how it works, but the trouble im having is that.

At 3:27, is that the transformer that he says increases power from 120v to thousands of volts?

At 7:08, what kind of electronic parts turn DC into AC?

If someone can give me a rundown on how this whole thing works would be great.

Another question. Could you make a homemade step up transformer? info on that would be great to.

here is the video https://www.youtube.com/watch?v=fWkTcAIuAE4

Thanks.

 

[Reloadron]

We have several members here in this little colony who love this stuff. Would have been better if the thread title was Spark Gap Transmitter and in the High Voltage section. The ignition coil on a car transforms 12 volts DC to thousands or volts to bridge a spark plug, so yes, with patience (and a hell of a lot of wire) a home brew spark coil (induction coil) can be fabricated. I am not sure how he did the DC to AC in the clip. There are numerous ways to go about doing it. All I saw was when he ripped what looked like a sand power resistor off a board he cooked.

Hopefully one of our resident HV peeps will wander in with some ideas to share.

Ron

 

[KeepItSimpleStupid]

I'm going to go way back in time a bit and give you this article to read: https://www.electro-tech-online.com/custompdfs/2012/01/The20Model20T20Ignition20Coil20-20Part201.pdf

AND back before electronic ignitions =, we had the point ignition system. It has a capacitor, coil and a gap (the spark plug). The spark plug wires could act as an antenna. Resistor plugs and wires eliminated some of the noise.

With an AM radio we used to hear tick tick tick tick... depending on the RPM of the engine.

Essentially a miniature radio transmitter.

What isn't clear in the video is that the transmission was morse code. The synthesized voice is part of the shop props. It does not occur. Voice is not transmitted.

Now it is possible to create an oscillator using a spark gap and I've fixed those used in lighting an ARC lamp. The lamp needs about 40KV to start.
So, you can effectively do the same thing here. Create an oscillator. The KEY allows the oscillator to run for a certain amount of time. The spark gap tunes the Oscillator. The spark gap breaks down depending on the distance apart and the dialectic constant of air.

 

[cowboybob]

Blackgt97,

I am Amateur Radio Operator (K4NFF) and have experience with your query.

More than willing to help, but I feel compelled to add some caveats first...

Keep in mind that any manner of electromagnetic Pulse (EMP) is closely watched by the FCC (not to mention the NSA, TSA, CIA and all the alphabet soup Feds). A spark gap transmitter is a broad spectrum EMP device. i.e., it transmits across a huge range of frequencies and quite some distance if attached to an antenna.

Doing so requires a federal license (such as mine) and at that you would be limited to very specific frequencies, something that is inherently not possible with a spark gap device.

That said, probably the easiest way to create this is to, as mentioned in a previous post, get a 12 volt (DC) auto spark plug coil, some manner of a momentary on/off switch, a 12vdc battery and some spark plug high voltage wire and hook that sucker up. Additional components can be added to enhance the spark.

Don't forget that you'll be playing with some serious voltages (though low current); upwards of 35,000 to 50,000 volts. Probably won't kill you but it can knock you down (think TASER).

I can provide a schematic if you like.

 

[BlackGT97]

a schematic would be great. But i think were getting the wrong idea. I dont want to build one, I simply would like to understand how he increased his voltage. I dont know if he made a transformer or if he used a transformer from something else. Thats what is getting me. First he went directly from a 110v AC Plug. When he hurt the inverter, he hooked it up to a 12 volt DC battery. So a simpiler question is...how did he increas from 12v to thousands of volts? and how did he change polaraties?

 

[KeepItSimpleStupid]

Here is a link with a schematic: https://en.wikipedia.org/wiki/Spark-gap_transmitter

I think you missed a couple of things. He mentioned a Solar panel and 120 V inverter and that's how he gor power to the shop.

I also noticed a neon sign transformer. The block with big insulators on each side. See: https://en.wikipedia.org/wiki/Neon_sign_transformer That will get you about 15,000 V. Then the air-cored transformer (The clear plastic thing with posts and wire) increases it more.

Neon transformers are inherently current limited by design. His swiped resistor from a computer also help current limit.

 

[cowboybob]

Looked at the video. I think I see what your asking.

The battery (or solar panels) produce DC only (direct current: does not vary in amplitude), 12 volts generally.

Remember that the spark at the spark gap device was a short but steady arc, not a single zap like the spark one sees in a spark plug. The morse code was made up of short and long spark periods

To increase a DC voltage it is necessary to, first, convert the DC to AC (alternating current: does vary in amplitude) and then (secondly) feed this AC to a "step-up" transformer. Transformers will do nothing work with a steady DC only input, except heat up.

Ordinarily, in order to generate AC from a DC source you have use some manner of self-oscillating device (in the old days, a "Chopper" 0r "vibrator" device, or nowadays a solid state circuit (555 Timer or the like) whose output is an AC signal that is , essentially, a train of on/off/on/off, etc., DC pulses. Think of a rapidly blinking light.

A "step-up" transformer has a greater number of turns of wire in the secondary (output) than in the primary (input). For instance, a secondary with 1000 turns of wire and a primary with 100 turns of wire will boost an input voltage by a factor of ten (12 volts AC in, 120 volts AC out). That 120vac could then be fed to a 1 to 100 ratio transformer (100 turn primary with a 10,000 turn secondary) to produce 12,000 vac. A "step-down" is merely the reverse.

The inverter mentioned performs the above combined functions. It takes 12vdc and "inverts" it to 120vac.

They kind of glossed over what the guy did once he had to use a battery to power the spark gap transmitter. But whatever he used, he would have had to use something similar to what I described above.

 

[BlackGT97]

Here is a link with a schematic: https://en.wikipedia.org/wiki/Spark-gap_transmitter

I think you missed a couple of things. He mentioned a Solar panel and 120 V inverter and that's how he gor power to the shop.
.

Yes. I know how he repowered the batteries (with the solar panel). But when the inverter blew when he first tried the spark gap, He used a 12v car battery with out hooking it up to the inverter.
Thanks for helping me by the way.

 

[BlackGT97]

Thanks for that schematic, it really simplefied it. I was just confused by the voltage increase, and now i see it was a neon sign trnasformer.
Does anyone have a simple schematic for a step up transformer (something like anyone can make at home)? Just curious how to make a homemade one (if you can)
Note: I will not be trying to make one, just want to learn some of this stuff.

 

[cowboybob]

I know you said that you don't actually want to build a transformer, but I can't help myself.

You'll need:

- 16p steel nail (or bigger, just easier to manipulate) This acts as the transformers "core"
- Roll of insulated 22 to 26 gauge wire (preferably, shellac insulated, easier to wind)
- Some source of low voltage AC (< 15 VAC)
- Volt meter

Wrap one half of the nail with, as an example, 50 turns of the wire, leaving extra wire to connect to the AC source. This will be your primary coil.
Next, wrap the other half of the nail with 100 turns of the wire in the same fashion. This will be your secondary coil. Make sure there is a gap between the two coils.

The ratio of primary to secondary windings is 50 : 100, or 1 : 2.

Example: 10 VAC connected to the primary will result in 20 VAC at the secondary (1 :2, step up).
Reverse the connections and the secondary will read 5 VAC (2 : 1, step down).

NOTE: The actual number of turns of wire is your call. Fewer turns means less current carrying capacity; more turns means greater current carry capacity. Just remember the turns ratio of primary to secondary dictates the voltage change ratio of the transformer.

As an afterthought, this same rig, but with only ONE coil, connected to a simple flash light battery will make an electromagnet. Use it to pick up metal objects. Same physics going on, but using DC current only.

This site's post editor is weird!!??!

 

[BlackGT97]

i was thinking of making one with a LOW voltage power source. no way im experimenting with 110v lol. Thanks.