VBITNGC building & comment

[digi01]

the third assembly is psu.
sch is here:http://www.diyaudio.com/forums/showt...698#post765698

part list is here:http://www.diyaudio.com/forums/showt...311#post748311

the attached is the modified assembly of psu.
attention:the ne555 chip should be set up in reverse station!

[Franz G]

For the tube which needs something between 35-0-35 & 100-0-100 @ 15+ mA or so...

Please, don't confuse people, this statement is completely wrong!

Again: for the tubes anode voltage, a single 35V to 45V secondary is needed. Please look at the schematics!

We use a voltage doubler circuit, so called Greinacher circuit.

Franz

[planet10]

Originally posted by Franz G
Please, don't confuse people, this statement is completely wrong!

Again: for the tubes anode voltage, a single 35V to 45V secondary is needed. Please look at the schematics!

We use a voltage doubler circuit, so called Greinacher circuit.

Completely wrong? I could have been clearer...

From the schematic you have plus/minus 45-63VDC. The original used +/- 35VDC and we talked with supplies north of 1/-100.

True that the "official" board uses a doubler, but those that don't want to use a doubler it is a perfectly valid (some would say better) approach to use a bridge & a dual secondary trafo.

dave

[wim]

Franz (or Zang), can the diodes D9+D10 (1A 1XYS 1-16D in the BOM) be replaced by the more common types 1N4007?

Thanks.

Dave, i do not understand your point. A simple and common low current trafo of 20-0-20 VAC is good for the job, with both windings in serie. What you get is 2*20VAC = 40VAC, fine in the range Franz told us.

Or do you mean something else? My English is not perfect you know.

[Franz G]

Franz (or Zang), can the diodes D9+D10 (1A 1XYS 1-16D in the BOM) be replaced by the more common types 1N4007?

Of course, it will work with 1n4007.

Franz

[wim]

Thanks a lot Franz.

[wim]

Franz, what is the resistor on the photo in post 31, on the backside of the PCB? Is that resistor named in the BOM or is it a fix, or additional?

And do you mean in also post 31 that the IC must by placed 180 degrees rotated than the PCB says?

Thanks again, and sorry for all my questions.

[Franz G]

Wim

Yes, the silk print is showing the NE555 in the wrong orientation.

About the resistor under the board: wait the answer from Zang. It seems, as he did not insert the trimmer pot and the resistor in series and replaced them by a fixed value under the board.

I am sorry about the errors on the silk print! I checked many times the solder side, but not enough the parts side. And I did not use a PSU board from Zang up to now.

Franz

[wim]

Thanks again Franz.

For the resistor at the bottom off the PCB i will wait as you told (mayby if i place the trimmer pot the resistor is not nessesury).

I (and all other builders i hope) will place the NE555 at 180 degrees turned around.

Don't wory about the mistakes. if we have a good communication on this forum it will be no problem, in fact it is part of the hobby!.

Till later,

Wim

[wim]

Sorry, but here i am again.

Franz, looking at your recently posted picture of the Murs on the PSU board: In the first place you changed de Murs and the C's (but thats no problem), but what is a problem I.M.O, you mounted all the Murs wrong. (cathode = anode and anode is cathode).

Please correct me if i am wrong, but i am pretty sure of it.

Best way to see it is to follow the schematic off the PSU and look good to the mountingway on your board.

If you lay down a Mur on your desk with the black plastic side in front of you, the left connectionwire is the cathode.

Hope to hear from you about it.

Till later,

Wim