I'm going to build a small and simple tube amplifier, and found a schematic which will be used for it.
Everything is clear except for the transformer. Here is the Circuit:
It doesn't say the exact values, just the output voltage after the full wave rectifier. What are the values thet should be used for the transsformer? Any recommendtations on one to use is cool also!
Everything is clear except for the transformer. Here is the Circuit:
It doesn't say the exact values, just the output voltage after the full wave rectifier. What are the values thet should be used for the transsformer? Any recommendtations on one to use is cool also!
I guess since I live in Europé, it should just be a 230 V AC in, with two outputs, one 6V AC, and one 290 V AC. Is that right. Do you know of a good Company that makes these, at a decent price (I don't have a big budget for this)?
I guess, what made me confused, was that they stated the voltage, after the full wave rectifier.
Also, regarding the 6V out, AC, there are Three Components, V1 to V3, what are these?
I guess, what made me confused, was that they stated the voltage, after the full wave rectifier.
Also, regarding the 6V out, AC, there are Three Components, V1 to V3, what are these?
Your schematic asks for 290 DC, not AC. Here are some formulas to calculate the AC needed before the bridge to get a particular DC after the bridge.
http://www.hammondmfg.com/pdf/5c007.pdf
Hi Fun Stuff, welcome to the forum.
Don't know if you need to read our sticky thread on safety, here's a link to it anyway
http://www.diyaudio.com/forums/tubes-valves/30172-safety-practices-general-ultra-high-voltage.html
How much of this schematic are you going to use and to what end ?
Don't know if you need to read our sticky thread on safety, here's a link to it anyway
http://www.diyaudio.com/forums/tubes-valves/30172-safety-practices-general-ultra-high-voltage.html
How much of this schematic are you going to use and to what end ?
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This schem. is for control reverb. device for guitar amp. It's not for audio listening. You can use every first stage /with tube 6SN7/ from DIY audioprojects in this forum and add interstage cap, about 4 -10 uF/250v to Your /maybe/ SS amp. If You want for begin to build simple tube amp, You can find the tread for SE ECL82, PCL86, ECL86 on this forum, for example.
If You need 290 v AC, You must divide it to 1.33 /if You use diodes rectifier/ to receive AC U from power transformer.
If You need 290 v AC, You must divide it to 1.33 /if You use diodes rectifier/ to receive AC U from power transformer.
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So, according to that, the secondare voltage is just the (Voltage D.C)/0,9 = 290/0,9 = 322 V. So if I have 230 V going in, and then have 322 V and 6 V going out, then the turns ration should be:
1: 1,4 &
1: 0,026 = 38 : 1.
Is this correct. Where can I find a transformer with these values. Or maybe it's better to first turn the A.C. down, to American standard (110 V A.C.), Before going to the transformer. And then have:
1 : 2,9. &
1 : 0,0545 = 18,34 : 1.
Or maybe it's easier to go to a higher value voltage, after the transformer, and then bring it down there?
Also, it seems that the standard for heater voltage is 6,3 V, and here it is 6 V. Is it better to go with 6,3 V?
Oh, I get it. So where should these Connections be made on the tube legs, in the schematic, one only see the 3 Connection, not the 4 & 9. Are these legs/connections 3,4 and 9 on the tube?
Sory, my mistake....If You need 290 V DC..../Why in schem. is shown 230 v? Must be 290 v/.
290/1.33=220 v approx. You need PT with secondary coil 220 V.
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6.3 Vac is ideal, but + or - 10% is OK with most valve components. The original design may have called for a specific power transformer to be used that happened to have a 6 Vac winding. Perhaps you could supply us with a link to the original article ? Note that a 6 Vac winding may measure 6.5 Vac or more off load. If lightly loaded it may still read above 6 Vac.
The 7247 has two triodes inside the glass bottle each with it's own heater filament. If the filament supply voltage is 6.3 Vac then the filaments are connected in parallel. This is achieved by connecting one side of the filament supply to pin 9 and the other to pins 4 and 5 bridged together. (If the filament supply is 12.6 Vac only pins 4 and 5 are used driving the filaments in series. Pin 9 (a centre tap between the filaments) is not needed.)
Pins 3 and 8 are the cathodes, not sure why pin 3 is bridged with pin 4 on the schematic instead of pin 5, perhaps an error
Here is a link to the 7247 valve specs showing pin (leg) details.
7247, Tube 7247; Röhre 7247 ID6150, Double Triode
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So, then I need approx. 322 V rms value, after the transformer, to get the 290 after the full wave rectifier.
Is it best to use a 1:2 stepup transformer, giving 460 V rms (if I remember correctly, it was over a year, since I checked the math), and then dropping the voltage, or can one find 1: 1.5 = 2 : 3 transformers (giving 345 V rms)?
I found some 1:4 transformers when searching, and they were for audio, I didn't have time to check if they could be used with higher voltage.
I didn't find 1 : 2 transformers, or 1 : 1,5 transformers, are they unusual?
I don't want to pay a lot of money for a specialist audio transformer, to put in a Power supply.
FULLWAVE BRIDGE Capacitor Input Load
DC = 1.41 X AC. So AC into the rectifier = 220, and DC out of the rectifier with a capacitor smoothing would equal 310VDC peak, depending on current draw might be more like 290VDC.
It sounds like before you get into something over your head and will end up just being confusing, you might want to read up on electronics like the US Navy's NEETS manuals.
You'll need a power transformer with 220VAC in and about 220VAC out and 6.3VAC out. You'll have to find out how much current you'll need. It should cost you something like 50-70 euros.
DC = 1.41 X AC. So AC into the rectifier = 220, and DC out of the rectifier with a capacitor smoothing would equal 310VDC peak, depending on current draw might be more like 290VDC.
It sounds like before you get into something over your head and will end up just being confusing, you might want to read up on electronics like the US Navy's NEETS manuals.
You'll need a power transformer with 220VAC in and about 220VAC out and 6.3VAC out. You'll have to find out how much current you'll need. It should cost you something like 50-70 euros.
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It's V AC after rectifier = (1/ 0,9) * V after transformer (rms value).
Giving 290 = (1/0,9) * V after transformer =>
V after transformer = 290 / 0,9 = 322. So we need 322 V, rms value, after the transformer (see the link in my last post for reference).
It's not complicated. My question was just regarding the suitable transformer to use, and their availability and prices.
Giving 290 = (1/0,9) * V after transformer =>
V after transformer = 290 / 0,9 = 322. So we need 322 V, rms value, after the transformer (see the link in my last post for reference).
It's not complicated. My question was just regarding the suitable transformer to use, and their availability and prices.
(1/0.9) * V after transformer is for just a resistive load, you have a capacitive load, giving you:
V (Peak) D.C. = 1.41 X Sec. V A.C.
V (Avg) D.C. = 0.90 X Sec. V A.C.
I D.C. = 0.62 X Sec. I A.C.
Depending on your capacitor and current, you can have from 0.9 to 1.41 times the AC. Download PSUII from duncanamps.com It will tell you what voltage transformer you'll need.
V (Peak) D.C. = 1.41 X Sec. V A.C.
V (Avg) D.C. = 0.90 X Sec. V A.C.
I D.C. = 0.62 X Sec. I A.C.
Depending on your capacitor and current, you can have from 0.9 to 1.41 times the AC. Download PSUII from duncanamps.com It will tell you what voltage transformer you'll need.
But, the capacitor only works to stop DC voltage, when no signal is coming in to the amp (say from your CD player), when it's Active, the amplifier, we have a AC current, and then the capacitor lets it through, and then we only have a resistor, thus giving a resistive load (with the two resistors), and not a capacitive.
It may be a capacitive load though. Would be cool to have this straightened out also.
Look into guitar amp, most have reverb circuit. Look at guitar amp schematics and find something similar and Check places like
Small Bear Electronics Stock List Home Page
https://www.tubedepot.com/t/diy-central/transformers-and-chokes
Mojotone Amplifier Transformers
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