8 Dec
2021
8 Dec
'21
3:14 p.m.
That would depend on the type and size of wire (solid core, stranded,
strands of stranded, etc.).
On 12/8/2021 5:06 PM, pbirkel at gmail.com wrote:
Seems to me that the actual coil resistance will limit
the max-current at lower voltages. 20 A through wire sized for 1 A seems ... unlikely?
-----Original Message-----
From: cctalk <cctalk-bounces at classiccmp.org> On Behalf Of Mike Katz via cctalk
Sent: Wednesday, December 8, 2021 5:58 PM
To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>;
wrcooke at wrcooke.net
Subject: Re: PDP-11/70 Boards
More accurately up to it's rated wattage "Power = Voltage * Current"
after all.
If you have a 100W max variac you can draw 20A @ 5V (approx) but only 1A at 100V.
On 12/8/2021 4:44 PM, Mike Katz via cctalk wrote:
"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