The heaters in my 6550 push-pull home brew have been supplied from a spare laptop SMPS which has now given up the ghost. I've organised an AC supply from the mains tx, but now have loads of hum and can't use the relay input switching.
To save having to rebuild the whole thing, can someone suggest a straightforward DC supply circuit which will give me 12.6v (running each pair of 6550s in series) at about 6A?
DC Heater supply
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pre65
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#2
Hi Shane-have you only got the one 6.3v AC secondary on your transformer ?
Could you not use the 6550s at 6.3v and make up a DC supply with shottkie diodes and a cap (as in WD forum FAQ) ?
Could you try a pseudo centre tap with the AC heating ?
Could you not use the 6550s at 6.3v and make up a DC supply with shottkie diodes and a cap (as in WD forum FAQ) ?
Could you try a pseudo centre tap with the AC heating ?
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)
#3
You shouldn't need DC on the 6550's, just the input stage. Check the pairs in the push pull are wired with the heaters in phase, that will help them cancel.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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shane
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#4
True, but I'd need to redo all the heater wiring since none of it's twisted and run an extra cable from the PSU to the amp for the DC supply to the relay switching. The (usually well hidden) tidy person deep inside me would prefer to have a single cable between the two which would then have to have six cores (heater AC, 12v DC, two levels of HT and earth) without the heater current inducing hum into the HT over it's six feet.
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pre65
- Amstrad Tower of Power
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#5
How about getting another laptop power supply ?
If you give me the details i will have a look around for you.
If you give me the details i will have a look around for you.
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)
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shane
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- Location: Kept in a cool dry place.
#6
Sorry Philip, didn't see your post. The transformer has two 6.3v windings and with a six foot umbilical I'd rather have 12.6v at about 3A than 6.3v at 6A.
The other point is more psychological, in that as it was, the amp sounded really good, so I'm reluctant to change too much in case I spoil it!
I just re-read my original post and realised that I didn't make clear that the existing arrangement uses 12.6v DC, so I'm trying to maintain the status quo.
The other point is more psychological, in that as it was, the amp sounded really good, so I'm reluctant to change too much in case I spoil it!
I just re-read my original post and realised that I didn't make clear that the existing arrangement uses 12.6v DC, so I'm trying to maintain the status quo.
#7
Well, if thats what you need, just use PSD to design a supply using a toroid, some low voltage drop diodes, and big caps, if you can get them a high current choke would help as well.
The problem is that it would nag at me, for the sake of some rewireing, you are generating huge current spikes in the DC supply, and I would worry that would affect something.
The other option, is feed it with AC, then jsut rectify and regulate for the first valves near the first valves.
The problem is that it would nag at me, for the sake of some rewireing, you are generating huge current spikes in the DC supply, and I would worry that would affect something.
The other option, is feed it with AC, then jsut rectify and regulate for the first valves near the first valves.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.