PDP-11/70 Boards

Mike Katz bitwiz at 12bitsbest.com
Wed Dec 8 16:44:14 CST 2021


"As a general rule, a variable transformer (Variac) can provide full 
rated current at any output voltage. So a 2.5A unit can provide 2.5 A at 
1V, 10V, 120V, etc. With a 20V output, that is 50 VA (Watts, sort of)."

Up to the current rating of the variac.  When you draw more current than 
the transformer can deliver then the voltage will sag.

On 12/8/2021 4:22 PM, Will Cooke via cctalk wrote:
>
>> On 12/08/2021 3:58 PM Rob Jarratt via cctalk <cctalk at classiccmp.org> wrote:
>> So, to supply the bricks on the bench, would a variac rated at 2.5A be OK? I am not sure I know how much current the bricks will draw at 20VAC, and at what voltage the 2.5A rating is given. Otherwise, would this do the trick? https://cpc.farnell.com/block/steu250-48/transformer-250va-230-400v-2-x/dp/TF01418?st=24v%20transformer
>>
>> Thanks
>>
>> Rob
>>
>>
>>>> JRJ
> As a general rule, a variable transformer (Variac) can provide full rated current at any output voltage.  So a 2.5A unit can provide 2.5 A at 1V, 10V, 120V, etc.  With a 20V output, that is 50 VA (Watts, sort of).
>
> Will
>
> "I was born not knowing and have had only a little time to change that here and there."
> Richard Feynman



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