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Re: Some questions on Power supplies [message #9380 is a reply to message #9370] Mon, 28 November 2005 20:14 Go to previous messageGo to next message
2wo is currently offline  2wo
Messages: 44
Registered: May 2009
Baron
There may be no best way.
If you make a design decision, to use a cap input or choke input, (which is best to use in a given application, I will leave that to Mr. Jones) Then you must work backwards. Do you have a bit of iron that you want to use, an off the shelf item, or will you have something custom wound.

If I were to start with a clean sheet of paper I would use a CT full wave rectifier as my first choice, one tube, most of the time or two SS diodes. clean and simple. And buy the transformer that supply’s, the needed voltage. There are some good multiple tap transformers such as the Angela universal or the DIY lady day that can fill many applications.

If I have a given transformer and a full wave bridge, will get me the voltage I need, then that is what I will use.

As to what rectifier to pick, well this gets personal. Of course there is tube versus SS. Let’s keep it to tube for now.

First any tube we choose must be able to supply the current and voltage we need. Next, are we constrained to 5V or 6.3V heaters? Or not. That’s the easy part.

Next we can divide the remaining tubes, into directly heated, such as the 5U4 and 5y3.Or indirectly such as the 5v4 or 5ar4. One advantage of the indirectly heated rectifier is a slower ramp up of the B+. How much this matters is up for debate.

Next up Voltage drop. Depending on the tube 20V to more than 70V, more or less. This can be useful when you need a bit more or less voltage.

From here on it’s my tube is better then your tube. So let your ears and your wallet be you guide…John




Re: Some questions on Power supplies [message #9381 is a reply to message #9379] Mon, 28 November 2005 21:03 Go to previous messageGo to next message
2wo is currently offline  2wo
Messages: 44
Registered: May 2009
Baron
Give a go.
I think you are underestimating the teaching potential of this tool.

Set something up, then change one thing at a time, try different tubes see what it dose to your voltage . Gee dose raising the second cap from 100uf to 220uf do much?

Take one transformer, say your 275-0-275 and run it thorough it’s possible permutations

full wave. Cap input.
Full wave Choke input

full wave bridge same as above.

Hey for extra credit try have wave.

A few pointers on using Psu2

referring to Damir’s post. You see that he runs for something like 2000ms after a delay of 0 sec.

I like to change the delay to say 30 sec sometimes to see what is going on after things settle down. Just beware that the graphs will look nasty , until you look at the Y axis and see how small it really is …John


PSUDii and settling [message #9389 is a reply to message #9381] Thu, 01 December 2005 18:29 Go to previous message
PakProtector is currently offline  PakProtector
Messages: 935
Registered: May 2009
Illuminati (2nd Degree)
I have played with many variations of tube PS with that Sim program. I don't thing that the tube warm up was properly modeled. I have examined two slow heating tube diode PS. Both were L-C and both showed considerable overshoot with PSUDii. No such overshoot was observed in the real world with tubes warming up fairly slowly.

I did try a hot switching ON-OFF-ON and found it did behave as PSUD predicted, leading me to the conclusion that they have a single parameter set for the tube diodes( or pairs of diodes ) which does not truthfully show the warm-up behaviour.

When I used Hg-vapour diodes, such as a pair of 816's I was able to see the current waveform in the brightness of the pretty blue glow. Even caught the oscillations as predicted by PSUDii.
cheers,
Douglas
cheers,
Douglas

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