by Brendan » Tue Dec 31, 2013 12:09 pm
I see GS, if you're are an electronic hobbyist, a variac can be a very useful tool for testing and experiments. Very flexible as you said. I just thought that you were considering that option purely to run a 10amp element or two :) If you have the option and availability of the equipment, well then it's no problem.
Although modern solid state components can generate a lot of heat, their size and cost outweigh a large, heavy transformer for overall cost analysis and efficiency (in terms of producing a commercial device, different story for hobby equipment obviously). Where possible with resistive loads, a zero cross switching topology can be used to eliminate switching losses and noise/harmonics...in our case of heating elements, smoother control is derived by utilising the much less efficient phase angle control which is normally employed for inductive loads due to the phase shift between voltage and current.
In regards to your variac...be mindful of some of the cheap Chinese built devices on eBay. Can get some real shockers on there. I think you're in the right mind to be 'scrounging', as an old well-built variac can last forever if maintained well. I have known of a few electronic shops near where I am which were going out of business due to people not getting tv's and amps repaired so much anymore, and they were parting with a lot of their equipment. You should also keep an eye on eBay for second hand ones that may pop up near to your locality...if you look to RS, you will pay through the nose and I assume as a hobbyist, that is not something you are prepared to do.
Good luck mate :handgestures-thumbupleft:
Last edited by
Brendan on Tue Dec 31, 2013 12:12 pm, edited 1 time in total.