Hello all, I have been in the process of building a power console of sorts for testing and prototyping tube equipment.
For my heater outputs, I would like to make it adjustable from ~0-12.6v dc and ac.
I was thinking about using a 317T with a pass transistor, what are your thoughts? Also, I know that the 317 datasheet shows an AC regulator, but some questions arise from this:
1) is there a way to adjust this output voltage with a pot
2) will the clipped sinewave forms caused by regulating the ac peaks induce any noise into the heaters?
one further note: I have seen circuits for a LM317 and 2995 transistor, which seems the simplest, however radioshack no longer carries that transistor. Is there an equivalent that I can use that is fairly common? I think the 2995 wast the complimentary device to the 3055 ( correct me if I am wrong.)
Also, what about just switching a 3055 backwards in the same circuit, since it is a bipolar device?
I am more into tube stuff than hollowstate... so any help in this area is happily taken..
For my heater outputs, I would like to make it adjustable from ~0-12.6v dc and ac.
I was thinking about using a 317T with a pass transistor, what are your thoughts? Also, I know that the 317 datasheet shows an AC regulator, but some questions arise from this:
1) is there a way to adjust this output voltage with a pot
2) will the clipped sinewave forms caused by regulating the ac peaks induce any noise into the heaters?
one further note: I have seen circuits for a LM317 and 2995 transistor, which seems the simplest, however radioshack no longer carries that transistor. Is there an equivalent that I can use that is fairly common? I think the 2995 wast the complimentary device to the 3055 ( correct me if I am wrong.)
Also, what about just switching a 3055 backwards in the same circuit, since it is a bipolar device?
I am more into tube stuff than hollowstate... so any help in this area is happily taken..
Variable ac filament voltage can be obtained by connecting the primary of a filament transformer to the output of a variac. Added advantage is that u will have sine wave supply for filaments.
However filaments are better supplied with DC voltage, preferably slow rising at power on to increase filament life.
Gajanan Phadte
However filaments are better supplied with DC voltage, preferably slow rising at power on to increase filament life.
Gajanan Phadte
I don't know the current level nor your input voltage, but the standard regulator like the 317 can perform poorly, especially if the difference between the input voltage and output voltage is different.
Instead of a standard regulator, a simple switcher could be used that would far more efficient. Not only does better efficiency reduce power consumption, it can also reduce heat sink size (saves PCB real estate) Adjustable switchers can be controlled like the 317. A google search for "Simple Switcher" should turn up loads of datasheets for varios switchers. If Noise is a concern, it can be reduced with a PI filter (ie Inductor and pair of capacitors).
Although you won't be able to produce a 50/60 hz AC output using a switcher (nor the LM317) (DC only).
If the output current is above about 4 Amps, you'll probably need to step up to a Buck Convertor (Search for "Buck Controller), which uses an external (non-integrated) Switching Transistor.
I believe most Simple switchers include a slow-startup option that could be used to slowly raise the output voltage as discussed in this thread.
Instead of a standard regulator, a simple switcher could be used that would far more efficient. Not only does better efficiency reduce power consumption, it can also reduce heat sink size (saves PCB real estate) Adjustable switchers can be controlled like the 317. A google search for "Simple Switcher" should turn up loads of datasheets for varios switchers. If Noise is a concern, it can be reduced with a PI filter (ie Inductor and pair of capacitors).
Although you won't be able to produce a 50/60 hz AC output using a switcher (nor the LM317) (DC only).
If the output current is above about 4 Amps, you'll probably need to step up to a Buck Convertor (Search for "Buck Controller), which uses an external (non-integrated) Switching Transistor.
I believe most Simple switchers include a slow-startup option that could be used to slowly raise the output voltage as discussed in this thread.
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