D-lator Tutorial step by step as I do it.

[Structo]

Now I am getting confused (not unusual).
On a couple schematics I have it shows a 47uf bypass on Vb, but on a couple others I have this is notated at 4.7uf.

I thought I had read somewhere in my search that it really is a 47uf.

Which one is correct for the Dumbleator 1?

[ToneMerc]

Is there another PT that would work well for this?

The key is what type of enclosure, the trick is finding a PT form factor that's compatible with a 1RU enclosure. I was going to use hammond PCB trannies or a custom torroidal. I also had Heyboer quote me a price on a small open frame 140/6.3v, but I never followed up and placed an order.

Outside of an 1 RU enclosure I think you can use any scheme to get yourself 320-350VDC under load and then modify your voltage string accordingly. I took Henry's advice and used a Fender reverb power trans and I have also used a Stancor 8416.

Check out the D'lator II it has the choke

My understanding is that the 47uF was actually used, however others have used the 4.7uF with sucess.

[Structo]

The tranny is confusing me.
On one hand it is said it is a 135v secondary with no center tap.

Is the diode arrangement on the Dumbleator a voltage doubler?

The Hammond 269JX was mentioned as a substitute for the Triad R-2C.



But when I look up the specs on that it says it is 500v with center tap.

The 269 AX is 250v CT.
Isn't that more in line what I want?

Thanks, I'll check out the Fender Reverb tranny.

[ToneMerc]

Secondary schemes

Doubler-no center tap..........unless u like smoke

Full wave-center tap

Half wave-Fender reverb trans diagram

TM

[ChrisM]

Not a bad idea at all to use the Reverb PT. Weber sells their version for $25, even includes a heater CT!

With a 260V secondary you should be getting around 368V DC (not under load), should work nicely.

[Structo]

Cool thanks guys!

I looked up the Reverb PT at AES and they list the specs as:

306 VDC @ 27mADC, 240 VAC @ 27mA, 6.6V @ 1.05A

[img:320:402]http://www.tubesandmore.com/cemirror/in ... wiring.gif[/img]

Will having the heater voltage at 6.6v cause any issues?

[Structo]

Checked out Weber and the specs are much better:

[img1105]https://taweber.powweb.com/store/wrvbptsch.jpg[/img]

So with this tranny, would I just use a half wave rectifier?

[ChrisM]

Yep, and the adequate filtering of course.

[Structo]

The Fender reverb unit shows three 1N4007's in series.
Is this something that should be done on the Dumbleator or is that overkill?

Then for the filtering, the D lator shows 33uf but the Fender shows 40uf.

Would this be better to use the larger caps?

In looking at the D lator II, it shows a loop around the dropping string.
What is the purpose of that?

[ChrisM]

First off the Fender Reverb unit and a Dumblator are two totally different things, not totally sure why your comparing them.

Anyways the Fender uses early silicon diodes. They don't have the specs of modern diodes. They were probably similar to a "weak" 1N4001, so they maybe could not handle the reverse breakdown voltage. Anyways point being, they are weak early si diodes so a bunch were strung together in series to "strengthen" them.

33mF is fine. Most electro have wide enough tolerances that some caps marked 33mF measure pretty close to 40mF.

[Structo]

Well I was comparing the power supply since I will be using the same type of PT.
So I wanted to see how Fender had theirs wired up.

[Structo]

I think if I do use the P-TF47609 reverb PT, that I will use a full wave bridge rectifier.
This tranny has a secondary of 240vAC.
But it is also rated at 306vDC.

I can't seem to find how to determine the voltage after the rectifier.
I know that each diode will drop .7v but what will be the actual voltage of the pulsating DC.
So I can figure out my dropping string.

I see on the PS schematic the first node is spec'd at 368vdc and the second 256vdc.

Also, the heater winding on this tranny is listed at 6.6v, is that going to be a problem?

Would a choke be a good idea on this supply?

[erwin_ve]

Hi Tom,

Take a look at the EU builders. We all use bridge rectifiers for our dlators. Almost the same voltages on secondary as with a reverb PT.
Airniles and me made some topics of it.

A 2,2 R (3w)resistor in series with your your heaters will drop the voltage a little.

[Structo]

Hey thanks,

I'm having trouble with this power supply.

If we have 135v on secondaries, and the rectifier is a doubler, how are we getting 368v on the first node and 256 on the second?

Doesn't the doubler type rectifier only roughly double the voltage, so this would be 270v?

So is this schematic wrong or what am I missing.

I plan on using a bridge rectifier but doesn't that also double the secondary voltage?
The PT I am looking at says it is 240vac sec.
Is the bridge going to put that at 480? Or is this where the 1.41 number comes in?

Believe me I have been reading all morning and I am not getting this.

[Structo]

By the way, I did read your thread where you built 3 Dumbelators.

Do you recall what your secondary voltages were and your B+ nodes?

http://ampgarage.com/forum/viewtopic.ph ... sc&start=0