Thank you for your help 🙏🏾as a novice, I’m still learning how much I am affecting the elements inside
Yes, I have added a 470K in parallel instead of 1K, so now I should be drawing 1.1mA… but that is probably not ideal at all, since the transformer is supposed to output 201mA which means I may need to change up my resistor.
Here is a nice Hammond application note on transformer loading.
It notes a full wave, CT, capacitor input should be loaded at no more than the secondary current rating.
So about 200mA max for the 273BX. A bit of extra de-rating never hurts if you like long lived projects.
Yes the 1K resistor is too low in value.
You must replace the 1k load resistor with a much higher value such as 100k. Also replace the 400V rated input cap with a higher voltage rating cap, such as 600V or higher. Placing resistors in parallel only reduces the lowest value further.
Please read the sticky posts at the top of the board. Please educate yourself on series and parallel resistance. Please educate yourself on Ohm's law.
Consider buying a book on building tube/valve amplifiers and reading it all the way through. Make notes. Ask questions. 🙂 Morgan Jones has a really great book. Merlin Blencowe has a great book too, and he even posts here from time to time.
Your transformer is very likely damaged. It is unwise to use it, especially not in any permanent build.
I appreciate that this is painful to hear. If you continue to use it only for testing/experimenting purposes, nobody will stop you.
The suggestion to use a Variac to slowly power-up any 'experiment' you might be using it on is a very good one. I didn't comment on this, but for me this is a standard practice as well.
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One should not try to teach himself basic electricity/electronics with tubes and the voltages associated with them. Learn the very basics with a 12 volt lab supply or batteries, even in you have no intention of ever building solid state amplifiers. In many ways, tubes are easier to make viable amplifiers with, but you need to know what to expect when you hook X to Y before messing with 300+ volts.
I think that since he used the phrase "instead of" that he replaced the 1k with a 470k across the rectifier output. Hope that's what he meant.
I assume he meant that he wired a rectifier center tapped filament winding center tap to ground. If so that could have resulted in an interesting moment.
Good point. Or maybe he meant he paralleled two 470K ohm resistors and replaced the 1k with that? That would be OK too.
We still do not know what his real load for this power supply is to be. Is it for a single-ended 6L6 amp?
@soulmerchant also no, this is for 8 tubes. Stereo pushpull EL34 based amp of my own design. I plan on using two triodes, one phase splitter (left and right channel) and I have 2 EL34 and another 2 EL34 for the other channel.
If the diodes shorted, this could happen.
You should always use the transformer with the correct fuse on the mains to prevent this. Unfortunately the transformer may be shot. Using 4 1N4007 2 in series on each leg will give 2000v peak reverse voltage.
The bleeder resistor should be 100k .
1k will dissipate 200 watts
You should always use the transformer with the correct fuse on the mains to prevent this. Unfortunately the transformer may be shot. Using 4 1N4007 2 in series on each leg will give 2000v peak reverse voltage.
The bleeder resistor should be 100k .
1k will dissipate 200 watts
Sander, what is the purpose of the 470K resistor? That value will not load the transformer enough to bring its output voltage down into the normal output voltage range.
I chose that value to lower the power dissipated on that 1K resistor.. 470K provides roughly half a watt.. versus 200watts with 1K.
OK, but what are you trying to do with this arrangement? To test a transformer and the rectifiers, you need to pull 50%-75% of its rated output current. So that's over 50 watts. If you only load it with 1mA, the transformer could produce as much as 25% higher voltage than the rating, and that would rise to a peak voltage over 600v.
If you are going to be designing and testing then do yourself a favour and get a dim bulb tester, is a must, in most instances it will prevent damage to components/transformers etc in the event of an error in wiring, schematics or accidental shorts due to mistakes or poor construction techniques, and when you do make a mistake (we all make them) the dim bulb tester might save the day - if you are not sure what a dim bulb tester is, google the term, there are plenty of examples/videos on line for you to follow. Don't be tempted to power up the circuit until you have the dim bulb tester in place, take extra care in making one, it is connected directly to the mains.
Now for some constructive criticism:- the photo you posted gives the impression that you haven't had much/any experience at breadboarding/constructing a circuit - it all looks pretty woeful, almost like you are asking for trouble, however we all need to start somewhere, and I'm sure things will improve as you gain experience - I suggest you troll through as many forum posts as you can looking at pictures, of other peoples work - see how they do it - watch some youtube videos - practise your soldering techniques - invest in a turret board, they are cheap and plentiful on sites like ebay, it can be used over and over - with a turret board your components are safely anchored, the circuit is easier to follow, you can draw out a pictorial of the circuit on paper and double check it is correct before wiring and powering up. If you don't want to invest in a turret board then a few rows of small brass wood screws screwed into your particle board will also work, keeping the wiring neat is an advantage when it comes to asking for help on the forum - forum members will find it easier to spot errors when it comes to photos.
Now for some constructive criticism:- the photo you posted gives the impression that you haven't had much/any experience at breadboarding/constructing a circuit - it all looks pretty woeful, almost like you are asking for trouble, however we all need to start somewhere, and I'm sure things will improve as you gain experience - I suggest you troll through as many forum posts as you can looking at pictures, of other peoples work - see how they do it - watch some youtube videos - practise your soldering techniques - invest in a turret board, they are cheap and plentiful on sites like ebay, it can be used over and over - with a turret board your components are safely anchored, the circuit is easier to follow, you can draw out a pictorial of the circuit on paper and double check it is correct before wiring and powering up. If you don't want to invest in a turret board then a few rows of small brass wood screws screwed into your particle board will also work, keeping the wiring neat is an advantage when it comes to asking for help on the forum - forum members will find it easier to spot errors when it comes to photos.