[Nerull]

Hey guys,

I'm going to get some boards made of these two beasts (dynatube "bamaslama", as shown in previous threads) This isn't for profit, but just to keep costs down. All those wanting a board can join (group buy maybe?) if not, you can always PM me and the first two people to PM me about it will get a board each. Otherwise really I'll have two unused boards, and I don't want to try balanced with this beast (the power supply would be enormous).

So if anyone's interested, please reply. Are group buys still banned here by the way? Again, I can always settle on selling the boards for the price I got them at to two lucky people

.

~Tom

*we need more dynatubes in the world! it can be done!*

 

[Nerull]

I'm in the process of making my own dynatube psu that's roughly what Dr. Gilmore presented (in schematic form) of the original dynatube thread. What I will be changing is the filament supply (from AC to DC) for lower noise (based on the 6AS7 datasheet). The other thing is the actual filtering capacitors (more in parallel for better filtering at given frequencies, low or high). I'll post the schematic shortly, and input will be greatly appreciated.

~Tom

 

[jarthel]

what psu design did you use?

 

[Nerull]

It's roughly based on the one attached:

The only thing is that I changed the filament supplies to DC, and will add more regulation if need be (mostly filtering). If you have any input, it'd be greatly appreciated! Most notably, a way to make it slow turn-on to help with tube life (avoiding the in-rush of current).

~Tom

 

[n_maher]

Quote:

Originally Posted by Nerull Hey guys, So if anyone's interested, please reply. Are group buys still banned here by the way? Again, I can always settle on selling the boards for the price I got them at to two lucky people . ~Tom

Tom,

They aren't banned but per the current rules you do need moderator (if not Jude's) approvall before even really discussing it. So I'd suggest dropping a PM to at least one of the DIY Mods and CC Jude on it asking for permission. Be sure to be clear about the not-for-profit motive and lay out exactly what it is you're going to do, at least that's what I've done in the past and it's gone without a hitch.

Best of luck,

Nate

 

[Nerull]

Will do n_maher!
Thanks for the advice, I wasn't really sure about how to go about that...
PMing as we speak...

~Tom

 

[jarthel]

I would prefer tube rectifiers for tube projects

 

[jarthel]

why not an ntc thermistor between the fuse and the ac switch?

for slow turn-ons, you would want the tube hot already before applying B+. so heaters must be instantly on but delay the B+ for say 30 secs. something like: http://img178.imageshack.us/my.php?i...5delay2bh2.gif

duration = 1.1 x Rpot x C. but from my experience, this is formula is useless for electrolytics since the tolerance is quite large.

I suggest wiring an LED + resistor from pin3 to pin8 (or pin4 as they are connected to the +9V). you can test the circuit (without the relays) using 9V batteries and use a watch to time it.

Connect the AC mains wire (I used the "line" wire (or is it called "hot" in other areas) to the normally open pin of the relay.

 

[jarthel]

for the transformer, I somehow think 140VAC secondaries are big using you'll be using a cap-input. why not an isolation transformer? not sure if this is cheaper but it'll surely be more than enough to product 150VDC.

 

[mrdon]

I'm interested!

 

[peterpan188]

Court me in too!

 

[jarthel]

looking at the schematics, it seems to me only the servo needs a pcb. the tube part can be easily done using P2P.

 

[jarthel]

does the board has enough space for big parts like PIO or teflon caps?

 

[Nerull]

Indeed it does, in fact, Dr. Gilmore made enough space specifically with that reasoning in mind (for caps like Mundorf or Jensen).
I'll always prefer a board to P2P, despite how easy it maybe to wire it up. I guess I'm just a board kind of guy and dislike P2P wiring (looks messy to me, and I'm OCD and I know it'd bother the crap out of me).

~Tom

 

[SilverCans]

put me down for some! hey, can start a group buy?