UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Other Discussions > Homebrew Equipment

Notices

Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members.

Closed Thread
 
Thread Tools
Old 25th Feb 2021, 6:37 pm   #1
indiosse
Triode
 
Join Date: Jul 2020
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 12
Default Load resistor on low voltage power supply

Hi all.

I have a few load resistors lying around.

I use them on DC power supplies, but am wondering if they would work on a low voltage AC power supply as well, say to test 0.5A on 19VAC supply.

Thanks
indiosse is offline  
Old 25th Feb 2021, 7:04 pm   #2
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
Default Re: Load resistor on low voltage power supply

They'll work fine so long as they can handle the power. 8.5W in the example you quote, but obviously current and power will depend on the resistance.
__________________
Graham. Forum Moderator

Reach for your meter before you reach for your soldering iron.
Station X is online now  
Old 25th Feb 2021, 7:29 pm   #3
Al (astral highway)
Dekatron
 
Al (astral highway)'s Avatar
 
Join Date: Nov 2006
Location: London, UK.
Posts: 3,496
Default Re: Load resistor on low voltage power supply

Quote:
Originally Posted by indiosse View Post

I have a few load resistors lying around.

I ... am wondering if they would work on a low voltage AC power supply as well, say to test 0.5A on 19VAC supply.

Sounds like this is from a simple transformer?


What do you want the test to establish? It may be productive to monitor voltage when that current is passing - if that's the current you will be needing. Depending on the relative size of the transformer, the volts may 'sag' at full current, so worth checking that.
__________________
Al
Al (astral highway) is offline  
Old 26th Feb 2021, 11:44 am   #4
PsychMan
Octode
 
PsychMan's Avatar
 
Join Date: Jun 2013
Location: Fleet, Hampshire, UK
Posts: 1,764
Default Re: Load resistor on low voltage power supply

Also worth bearing in mind that they will work for you just as they do on DC supplies, but only for testing purely resistive loads.

If you're making an AC supply, perhaps you're looking to work with inductive loads, in which case the maths gets more complicated than simple ohms law.

Adam
PsychMan is offline  
Old 26th Feb 2021, 6:06 pm   #5
Guest
Guest
 
Posts: n/a
Default Re: Load resistor on low voltage power supply

Quote:
the maths gets more complicated than simple ohms law.
The maths and arithmetic stay the same, it's the numbers that change from "simple" to "complex"*, any good scientific calculator will handle these. It is not hard at all, just a bit more long winded.

*complex numbers, not complex but A complex of two, just two, per number. Easy to see on graph paper, perhaps they should have been called graph or Cartesian (as in two dimensional) numbers.
 
Old 27th Feb 2021, 11:34 am   #6
russell_w_b
Dekatron
 
russell_w_b's Avatar
 
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,684
Default Re: Load resistor on low voltage power supply

Quote:
Originally Posted by merlinmaxwell View Post
Easy to see on graph paper, perhaps they should have been called graph or Cartesian (as in two dimensional) numbers.
Rectangular form, as opposed to Polar form, sounds less intimidating than 'complex'.
__________________
Regds,

Russell W. B.
G4YLI.
russell_w_b is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 11:06 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.