| ggherold@gmail.com: Nov 12 06:27AM -0800 On Friday, October 30, 2020 at 1:30:43 PM UTC-4, Runner wrote: > arrays, but it burned out almost instantly. I wasn't surprised of > course, but thought I'd give it a try. Any ideas as to how to vary the > power welcome. Re: varying power. Since the resistance of copper goes up with temperature (R is ~ temperature) controlling the voltage might be best. (no thermal runaway) Are you using AC or DC power. AC might be easier, get a transformer (maybe filament transformer?) and drive it from a variac. DC will be trickier ('cause that power has to go somewhere) and some PWM scheme might be the way to go. Or buy a variable DC supply... you can use it for electroplating when not staying warm. :^) In general I'm wondering why not try a heating pad and a nice down comforter? George H. |
| Phil Allison <pallison49@gmail.com>: Nov 11 01:43PM -0800 David Farber wrote: =================== > board, I mentioned in passing that the second channel audio amplifier > components were not installed. There are however marked out spaces for > them. In summary, any components that refer to CH2 do not exist. ** So you posted the wrong schematic. Bound to be many differences when the PSU only has to power 1 channel instead of 2. > As to > whether it is class D or class H (I don't think my electronics training > from the 1970's went past class C), ** No, classes G and H are more recent inventions. If you have not kept up with the literature (ie electronics magazines) since the early 70s you are living in the dark ages. Before the internet ruined everything, I used to buy 4 magazines each month. Only one of them is still published. Wireless World from the UK was the best, but it folded years ago. > I'll leave that up to you and in the > meantime, I'll turn to the internet to update my knowledge about the > alphabet soup of amplifier classes. ** Be sure not to confuse the topic with "alphabet people". ..... Phil |
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