Need to find replacement for EH Toroidal

[aron]

The EH Toroidal is being discountinued for us.

I did a little searching and came up with R.G.'s link:

AMVECO TE62012
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=TE62012-ND

How do I read this chart?
http://rocky.digikey.com/WebLib/Amveco-Talema/Web%20Data/62000%20Series%20Low%20Profile%20Miniature%20Transformers.pdf

Is it the no load voltage? 2X17.3 that define the ratio?

Would this be an exact replacement for the EH Toroidal?

[stephanovitch]

Is it a power supply transformer?

[stephanovitch]

If you want replace the EH transformer you must use a transformer with almost sames dimensions or same current if you know it.

[aron]

Yes, use like this:

http://www.el34world.com/projects/images/TubePedalSchematic.gif

I was going to build a few tube projects....

[stephanovitch]

Ok, i have ever made this transformer circuit, you must use a transformer with same voltage reverse connected with the first AC source

[stephanovitch]

To supply two tubes in this circuit you need 4mA minimum on your transfo out

[stephanovitch]

In my circuit i have used a 7VA toroidal for HT on 3 tubes. I think you can use the same power in your circuit.

[jaytee]

I think the numbers get a bit wacky because it's being used backwards. At no load with this transformer you would need to put 17.3 volts in to get 230 volts out. So at 12 volts in you would get less. If I have it right, about 160 volts out. Then the more you load it the more it would sag from there. If you want higher voltage out the 9 volt transformer would do that. Around 210 volts at no load.  At 3.2VA you would get 14ma at 230v easily enough for a few tubes (not including the heaters). What voltage does the EH transformer give out?

[aron]

This is what I found online for the EH transformer.

Primary 220-Volt 50-60Hz. Secondary 10-Volt@120mA x 2.

[jaytee]

I'm guessing that's the full load secondary voltage? If it is the 9v transformer would get you fairly close.

[stephanovitch]

If you use a 12V transformer you will obtain approximaly 320V rectified out (230*1.414) with no load.
If you want less voltage remove the 4.7k/3W resistor with higher value

[soulsonic]

Weber has a transformer that's intended to power tube pedals. It has a 12VAC input and a 260VAC output. I've used one before and it seemed to work alright. The only problem is that it's not small at all. I think it would probably be considered too large for many enclosures. The part # is WPDLPT.
https://taweber.powweb.com/store/pdlptsch.jpg

[aron]

>At no load with this transformer you would need to put 17.3 volts in to get 230 volts out.

Wait, how did you figure this out with the datasheet? Where is the ratio on the table?

Hmmmm are just reading the table backwards. So for 230V connect primaries in series and read the table to get the "input".

So the 62010 would give approx. 230V with a 10.2V input?
62031 would give 230V with 12V input?

[R.G.]

Let's play "Calculate the transformer".

A transformer ALWAYS converts voltage on whichever winding is being used as the primary to voltage on whichever winding is being used as the secondary by the turns ratio.

The turns ratio is always the same as the No-Load voltage ratio, because with no current flowing, there are no resistor losses to muck up the measurements. So to reverse engineer an unknown transformer, you always test at no load and get the true voltage ratio.

Measuring the transformer at full load will show a voltage drop at the winding being used as a secondary because of (principally) the resistance losses in the copper.

You can back-calculate the wire resistances by measuring the primary and secondary voltages under no load and full load, and also the load current. That drop in voltage with current comes from the wire resistance and you can then use Ohm's law to calculate an equivalent resistance that is the result of both primary and secondary wire resistance.

In the case of the 62012, the no load voltage is 17.3, the full load is 12.0, and the full load current is 133ma. That means the equivalent resistance referred to the secondary is (17.3-12)/0.133 = 39.85 ohms.

We can refer this to the primary by using the square of the turns ratio. The turns ratio is 230/17.3 (no-load voltage ratio) or 13.29 going from secondary to primary, so the resistance referred to the primary is (13.29*13.29)*39.85 = 7043 ohms.

So you could replace the 62012 with a perfect, no resistance transformer of ratio 230:17.3 with either a 7.043K resistor in the primary or a 39.85 ohm resistor in the secondary, and this perfect transformer with the resistor would act exactly like the 62012 as far as the load knew.

[petemoore]

I was going to build a few tube projects....
  You found the tube breadboards ?

[MarcoMike]

Here in Europe I found these... I'm not sure if there is what you are looking for Aron, but for sure there is quite a lot of transformers here:
http://www.banzaieffects.com/Talema-Transformers-c-996.html

[jaytee]

>At no load with this transformer you would need to put 17.3 volts in to get 230 volts out.

Wait, how did you figure this out with the datasheet? Where is the ratio on the table?

Hmmmm are just reading the table backwards. So for 230V connect primaries in series and read the table to get the "input".

So the 62010 would give approx. 230V with a 10.2V input?
62031 would give 230V with 12V input?

Yes that's it. The EH transformer says 2*10v out at 120mA. I'm taking that as being full load voltage out. So at no load the voltage will rise. Without measuring it I would guess it would rise to about 12v. So the EH transformer will be around 220v out for 12v in. At 2.4VA.
62031 is quite close, 230v out slightly higher output but much bigger at 7VA. 62011 will give 210v. 62010 will give 270v out. The actual measured numbers might not be so exact. It might be useful if you can measure the EH one if you want something that will match it closely.

[aron]

It seems like the 62031 is the one to try. About 1.85 inches square. Less than an inch thick.

The 62012 could be used if we don't mind less plate voltage (if I'm thinking correctly).

[puretube]

FRIEND...