# Re: how much does current matter?

```Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Ben,

```
After re-reading your question, I understood where you were going with your question. I don't know Tesla Map, but I do understand what it's attempt. The problem is that streamer physics has more variables than meets the eye, but power is certainly a major factor. How a streamer propagates and how far it will reach is a classic question from the novice to the experts on the subject. I am not the right person to shed any new light here. The best I could do is point you towards some of the literature I've read on the subject which has helped me get at least a concept of what is going on. They are not directed at the spark length of a Tesla Coil, but they are related.
```

Take care,
Bart

Tesla list wrote:

```
```Original poster: ben eells <squeels2171@xxxxxxxxx>

Hi Bart,
```
What I meant by that statement was if it is output wattage that determines streamer length you wouldn't need a transformer because output wattage = input wattage (of course output wattage will be slightly less because 100% coupling can't be achieved). Although the Tesla map program doesn't actually say this, one could determine that a transformer is not needed, because no matter what the voltage and current are changed to the input and output wattages should always be the same. (Assuming near 100% coupling in a transformer that isn't current limited) I do believe this to be incorrect though in a spark gap system. If it were correct I'm sure somebody would have built one already. I can't really speak on SSTC's because I know nothing about them.
```
Tesla list <tesla@xxxxxxxxxx> wrote:
Original poster: "Barton B. Ander son"

Hi Ben,

Wow, good question. You are correct in that input watts will always
be greater than output watts. The only possibility that both output
could equal input is if the input were also the output. Anything
else, and output is always more.

I don't understand the last statement regarding no need of the
transformer. You make a statement there, but you didn't say why you
determined this.

As far as max streamer length, well, it's pretty easy. Just measure
input watts vs. output streamer length, but note that if you take
concentric readings of input V and I, it's not power, it's volt*amps
which really doesn't tell you much. Some may say it's only about 10
percent off, but that's not accurate. You really need to measure true
input watts with a watt meter to determine input watts vs. streamer
length. That particular measurement takes into account all factors
throughout the sys tem. It's really the only way to determine coil
efficiency when spark length is the main factor.

Take care,
Bart

Tesla list wrote:

>Original poster: ben eells
>
>In my attempt to build a more powerful tesla coil I have come across
>this question. How much will the output current of your NST affect
>the length of your streamers. I'm using the program Tesla map to
>help design this coil and it calculates the max streamer length by
>the output wattage of the NST. Unless I'm mistaken output wattage
>can never be higher than input wattage. If this program is correct,
>and I'm sure it's not, I wouldn't need a transformer at all. So what
>is a better way to determine max streamer length given the output
>voltage and current of a NST?
>
>
>
>
>

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