# RE: [TCML] voltage divider

```Very simple ohms law: p= E^2 / R

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of David Nelson
Sent: Monday, June 23, 2008 8:12 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] voltage divider

Paul

Thanks for your post about voltage dividers. For measuring NST outputs what
power rating of resistors is required. I mean will 1/4 watt resistors work?
100W?

Dave Nelson
----- Original Message -----
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Monday, June 23, 2008 1:31 PM
Subject: Re: [TCML] voltage divider

> hi douglas
> im hoping this ascii drawing works but if it doesnt i can draw up a pic n
>
> basically you need resistors to divide the voltage down by a certain ratio
> for example 5kv -> 5v you would need a ratio of 5000:5 or 1000:1
>
> the resistors configred as follows
>
> HV+ O-----[=R1=]-----(meter +)------[=R2=]------(meter -)---O HV-
> for ac measurements HV+ = HV(hot) and HV- = HV(ground)
>
> where R1+R2 : R1 = 1000:1
> so the values can be any range of ohms/K/M ect
> if we use 10K for R1 we will need 9990K for R2
> reason for 9990K is because the 10K is included in both sides of the ratio
> this is because the HV will be seen by all resistors (R1+R2) but the meter

> will only see the 10k portion (R1)
>
> R2 can be made of any number of series resistors provided it adds up to
> 9990K ohms
> as an example you could have 9x1M + 9x100k + 9x10k (9000k + 900k + 90k)
>
> this circuit is best with either a digital multimeter or a
> CRO/oscilliscope
>
> the formulas are as follows
>
> v1 = max range of the meter
> v2 = required HV reading (try keeping it as multiple of 10 for ease of
>
>         v2-v1
> R2= ------  x   R1 v1
>
> if that didnt turn out well R2 = ( ( v1 - v2 ) / v1 ) x R1
>
> hope this helps
>
> --
> Regards
> BidSpec Electronics Engineering
> Mob: 0404 259 733
>
>
>
>
> douglas smith wrote:
>> i hear you guys talking about  voltage dividers for measurement of kv.
>> is that for meters or scopes?
>> i was hoping someone had a good schematic so it can measure my high
>> voltages
>> as right now my meter only goes to 750 a/c volts.
>> Ive never built one for  KV
>>
>>
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>>
>>
>>
>
>
>
>

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