Then, I say keep it simple ... - Naz - Tube DIY Asylum

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Then, I say keep it simple ...

Naz

In Reply to: Yes, it's a linear power supply. posted by grhughes on January 24, 2006 at 08:07:14:

Hi Ray,
I'm thinking that unless you particularly want a reference supply with stella load and line regulation a simple circuit would be best. Generally, ripple and speed are important factors in power supplies for tubes but load and line regulation (within reason) is less important. Therefore a simple zener to set the reference voltage and a pot or switched resister network across the zener to divide the voltage for the gate will be more than adequate.
The knee on HV zeners is not very sharp meaning the voltage will change to some degree with current through the zener. This will occur on line voltage variations, mainly due to mains fluctuations but also to a lesser extent, with changes in load. However, you can improve the performance significantly by adding a current source in series with the zener to provide it with constant current.
If you want to take it one step further add either a regulator chip, or a voltage reference combined with a transistor or IC. Frankly I do not see the need to go that far in your application and I would only go as far as adding the current source in series with the zener. I would also bypass the zener with a good high frequency cap of say 0.47uf, use a relatively low value switched resistor network across the zener of not more than 10K and couple the divider output to the gate via a resistor not exceeding 1K and preferably down around 100R. Oscillation should not be a problem.
The most important factors in my book are the use of good quality caps and a choke in a CLC arrangement on the input and a good quality cap on the output.
Regards,
Naz

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Follow Ups Full Thread

Topic - Anyone used the IRF744 mosfet as a power supply pass transistor..?.. - grhughes 08:59:03 01/22/06 (8)

Re: Anyone used the IRF744 mosfet as a power supply pass transistor..?.. - Naz 17:05:07 01/22/06 (7)

If you could choose.... - grhughes 07:08:45 01/23/06 (6)

I'd choose the right Mosfet ... - Naz 18:45:04 01/23/06 (5)

Yes, it's a linear power supply. - grhughes 08:07:14 01/24/06 (4)

Then, I say keep it simple ... - Naz 22:15:44 01/24/06 (3)

The IRF450 in TO3 is almost 13 clamcakes!. - grhughes 14:01:11 01/25/06 (2)

I found some useful info for you ... - Naz 00:53:42 01/28/06 (1)

Thanks a lot! That's a big help. - grhughes 08:54:02 01/28/06 (0)

Follow Ups

Then, I say keep it simple ... - Naz 22:15:44 01/24/06 (3)

The IRF450 in TO3 is almost 13 clamcakes!. - grhughes 14:01:11 01/25/06 (2)

I found some useful info for you ... - Naz 00:53:42 01/28/06 (1)

Thanks a lot! That's a big help. - grhughes 08:54:02 01/28/06 (0)

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