WAD Phono2 power supply.
- shane
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#61 Re: WAD Phono2 power supply.
Ta Dave! Yes that's possible. I'm going to stick a scope on it tomorrow which should show if it's ripple on the HT or heaters.
Voltages are as follows:
HT 259v
60ohm r 1.91v
2n3906 c-e 2.52v
MJE350 c-e 0.71v
Does that sound right?
Voltages are as follows:
HT 259v
60ohm r 1.91v
2n3906 c-e 2.52v
MJE350 c-e 0.71v
Does that sound right?
The world looks so different after learning science. For example, trees are made of air, primarily. When they are burned, they go back to air, and in their flaming heat is released the flaming heat of the Sun which was bound in to convert air into tree.
#62 Re: WAD Phono2 power supply.
Either the current source is broken, or you need more voltage across it. I would aim for at least 20-30v across the current source, so the voltage in needs to be 280 at least if the VR tubes are regulating at 259, the voltage across the 2n seems oj, but I would expect the mje to be doing the heavy lifting.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
- shane
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#63 Re: WAD Phono2 power supply.
Ok, that gives me something to work on tomorrow. I suspect the supply voltage is low. Bit more measuring to do...
The world looks so different after learning science. For example, trees are made of air, primarily. When they are burned, they go back to air, and in their flaming heat is released the flaming heat of the Sun which was bound in to convert air into tree.
- shane
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#64 Re: WAD Phono2 power supply.
Took some measurements just now. So I'm getting 230v out of the second transformer which gives me 286.2v out of the diode bridge. I then lose 3.6v across the 100r (282.6v) and 18.9 across the choke (263.. Finally, I'm losing the last 4.47v across the current supply, giving HT of 259v.
Is the loss across the choke excessive? It's 7uH, with a DCR of 510 ohms.
Is the loss across the choke excessive? It's 7uH, with a DCR of 510 ohms.
The world looks so different after learning science. For example, trees are made of air, primarily. When they are burned, they go back to air, and in their flaming heat is released the flaming heat of the Sun which was bound in to convert air into tree.
- pre65
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#65 Re: WAD Phono2 power supply.
Using Ohms law the current draw is
A) Choke 510r 37ma
B) resistor 100r 36ma
So near enough.
I might have some other chokes, I'll check the DCR on them.
A) Choke 510r 37ma
B) resistor 100r 36ma
So near enough.
I might have some other chokes, I'll check the DCR on them.
Last edited by pre65 on Tue Jul 04, 2017 12:44 pm, edited 1 time in total.
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- shane
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#66 Re: WAD Phono2 power supply.
Yup. Got that. What I'm getting at is do I need a choke with a lower DCR in order to increase the voltage into the current supply, or is it not that simple?
The world looks so different after learning science. For example, trees are made of air, primarily. When they are burned, they go back to air, and in their flaming heat is released the flaming heat of the Sun which was bound in to convert air into tree.
#67 Re: WAD Phono2 power supply.
But given that you are only dropping 3.6v across that, its not going to help much is it.If you need a tad more voltage then play with the resistor (100r) value.
230v Ac should give you more like 320v. I would either find a choke with lower DCR or mix and match VR tubes to aim at a lower HT. Say a 0A2 and 0C2
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
- pre65
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#68 Re: WAD Phono2 power supply.
Just amended my last post.
That was my thought, but you can't gain a lot of volts. If you halved the choke resistance you would gain about 9.5v.
How many extra volts do you need ?
The only thing necessary for the triumph of evil is for good men to do nothing.
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G-Popz THE easy listening connoisseur. (Philip)
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- shane
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#69 Re: WAD Phono2 power supply.
According to Nick the current supply needs about 20v across it. Given that the gas tubes are regulations at 259, then I need about 280v out of the choke. Just looked at the choke again, it looks like it's 15mH, rather than the 7mh I thought it was.
The world looks so different after learning science. For example, trees are made of air, primarily. When they are burned, they go back to air, and in their flaming heat is released the flaming heat of the Sun which was bound in to convert air into tree.
- shane
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#70 Re: WAD Phono2 power supply.
The world looks so different after learning science. For example, trees are made of air, primarily. When they are burned, they go back to air, and in their flaming heat is released the flaming heat of the Sun which was bound in to convert air into tree.
#71 Re: WAD Phono2 power supply.
No. You need a choke for the purpose of DC soothing.
Try without the choke in circuit and see how that goes.
Try without the choke in circuit and see how that goes.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
- shane
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#72 Re: WAD Phono2 power supply.
That's what I like. Simple solutions.
The world looks so different after learning science. For example, trees are made of air, primarily. When they are burned, they go back to air, and in their flaming heat is released the flaming heat of the Sun which was bound in to convert air into tree.
- pre65
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#73 Re: WAD Phono2 power supply.
I thought the choke was 15H, not 15mH ?
Those are common mode chokes you link to Shane, not what you need.
I've measured some other chokes I had but the DCR is no less than the one you have.
Would putting a small capacitor (1uf motor run) before the 100r resistor give you enough of an increase ?
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
- shane
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#74 Re: WAD Phono2 power supply.
Hmmm. Choke out of circuit. Hums like a mad bugger.
Not going to be able to do any more investigations for a week now due to work schedules, but I'll look for a better choke in the mean time.
Not going to be able to do any more investigations for a week now due to work schedules, but I'll look for a better choke in the mean time.
The world looks so different after learning science. For example, trees are made of air, primarily. When they are burned, they go back to air, and in their flaming heat is released the flaming heat of the Sun which was bound in to convert air into tree.
#75 Re: WAD Phono2 power supply.
What were the voltages like?
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.