/diy/ - Do It Yourself

It's useful as a power supply mainly. What components are you planning on using in it?

>>1215610
i want something like this.

what should i do to get 260V? should i use two of those so i get 230V from the other side? i know fuck about transformers in general so any advice will be useful.

>>1215613
Patience please. I know what to do but I'm too tired now.

>>1215613
Here's the idea. No calculations yet. Your transformer is way too big. I need a coffee.

your toroidal transformer is completely unsuited to the task. what you need is a transformer with an input voltage equal to your line voltage (either 120Vac or 240Vac) and two secondaries, one of around 200Vac to generate +250Vdc and either a 6.3Vac or 12Vac to power the heaters in the tubes. you can use 6.3V and wire the heaters in parallel, or put two in series and wire them to 12V.

if you like to live dangerously, you can get the 250Vdc directly from the power lines, with no transformer, and get shocked every time you plug something in.

doing the 2-transformer trick in >>1215713 is certainly doable, but it's heavy and expensive.

your toroidal transformer is completely unsuited to the task. what you need is a transformer with an input voltage equal to your line voltage (either 120Vac or 240Vac) and two secondaries, one of around 200Vac to generate +250Vdc and either a 6.3Vac or 12Vac to power the heaters in the tubes. you can use 6.3V and wire the heaters in parallel, or put two in series and wire them to 12V.

if you like to live dangerously, you can get the 250Vdc directly from the power lines, with no transformer, and get shocked every time you plug something in.

doing the 2-transformer trick in >>1215713 is certainly doable, but it's heavy, expensive, and takes a lot of space.

also, your toroid is rated for 120W, which is better suited to a power amplifier, rather than a pre-amp. but the voltages are wrong for a power amp as well.

>>1215608

>0-12-26V SEC

use it for a class D or AB amp or something

>>1215713
Did some calculation.
Tiny transformers, all the power required:
230V 12V 4,8VA -- 12V Heaters 4 EUR
230V 12V 1,8VA -- 260V Anodes 2 EUR

>>1215746
>class D
>tube amp
Now that's slightly interesting.

>>1215729
found a micro toroidal transformer with primaries of 115 and 240 and 2 secondaries of 9V, i could put them back to back and get 240V, very light and very little space, is this a bad idea?

>>1215794
how do i google these

>>1215887
okay found it its a "gerth". but how do i go with these two to the 260V output? how many of those do i need here?

>>1215608
tell us what voltage and current your amplifier is going to be designed to draw and i will happily read the values from the picture and tell you if it will work or not.

>>1215885
Have a look at the circuit diagram at >>1215713. The upper left transformer supplies 12VAC which is then rectified and stabilized for the heater(s). This is the +12V connection in the pre-amp diagram at >>1215613. The nominal voltage is 2x 6.3V = 12.6V. If you insert the (grey) diode in the ground pin of the 7812 you get 12.6V rather than 12V.

The other transformer produces the 230VAC that is rectified and filtered for the anode voltage of 260V. The voltage directly after the rectifier is about 325V and the resistors can be calculated to leave 260V as the loaded output voltage. The total resistance of the filter chain would be (325-260)/1.5mA = 433K or 2x 220K if you leave off the 8K2 resistor. The two capacitors can be the same as in the pre-amp, 47µF/450V.

Now the numbers in the pre-amp diagram do not add up: V1b (250-160)/68K = 1.32mA, V1a (250-140)/270K = 0.41mA, sum is 1.731mA but (260-250)/8K2 = 1.22mA. I used 1.5mA as the total anode current of V1a plus V1b to calculate the transformer. The net power is 3.8W.

>2 secondaries of 9V
9VAC is not enough for the heater circuit and 18VAC is too much, you would need to heat away a lot.
>back to back and get 240V
That's what I did, look at the diagram: 230|12 -> 12|230.

You do not need to use the suggested transformers, it's just the smallest solution. Any two 230/12 5W types will do equally well. Maybe 230/15 could also work for the anode voltage, didn't try it yet.

Good night for now, I need more sleep..

>>1215934
thank you. theres an equivalent of the transformator i mentioned but instead of two 9V it gives 12V. will read what you put if i can make up something out of it.

>>1215937
230/12 to 15/230 doesn't work. I'll leave it at that. Good luck.