Right-the simple DC 300b heater supply is now up and running,and with the 5V Hammond transformer,diode bridge and 10000uf cap running into 0.5R resistor (2 X 1R in parallel) i am getting 4.8V under load,which was the target.
I'm using the original Chinese 300b that came with the amp and the sound has changed slightly. Seems a tad more low end and a tad less sparkle in the mid. Will try the EH valves later on to see if they make a difference.
The hum is now much reduced and using KLS3 i am not troubled by noise in quiet bits on discs.
It is still my ambition to try one of the current/voltage regulated modules in the future but this will do me for the present.
300b filament module
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Mike H
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#17 DC 300B heater supply
What do you reckon on this idea?
Duncan's designer says 20mV peak-peak of ripple at the filament (R1). I should mention the '6 Ohms' would need to be made up by padding resistors as necessary
Duncan's designer says 20mV peak-peak of ripple at the filament (R1). I should mention the '6 Ohms' would need to be made up by padding resistors as necessary
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"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
#18
The biggest problem (unless you have a source) is finding a 100mH choke thats happy with a coupel of amps of DCWhat do you reckon on this idea?
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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pre65
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#20
Hi-the DC supply i made was done that way cos i happened to have a couple of 5v Hammond transformers left over from a dismantled project !
Are 10.5v transformers easy to source ? 10v would be enough if used with shottkies ?
I still would like to go with the Tentlab modules for the 845 when funds permit but in the meantime i hope to try a 10v CT transformer with the cathode resistors in the CT as recommended by our man in Bedford.
Are 10.5v transformers easy to source ? 10v would be enough if used with shottkies ?
I still would like to go with the Tentlab modules for the 845 when funds permit but in the meantime i hope to try a 10v CT transformer with the cathode resistors in the CT as recommended by our man in Bedford.
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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andrew Ivimey
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#21
Philip, what I have got is a 700-0-700 350ma transformer with 10 volt 5 amp windings plus 6.3 winding and 5 volt. Now you got to admit, that's tasty!
I have a couple of NOS 5-0-5 x2 5 amps transformers so they cook 845s a treat.
The original @tractor' had a 450-0-450 transformer with 3 amp 10 volt windings etc - again very useful!
I have a couple of NOS 5-0-5 x2 5 amps transformers so they cook 845s a treat.
The original @tractor' had a 450-0-450 transformer with 3 amp 10 volt windings etc - again very useful!
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Mike H
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#22
1,400V @ 350mA? 
Strewth...
Hold on chaps, it just happens that the TX has four 5V windings on it. I'm sure you could equally as well use 12V. Just needs a bit more 'padding out'
Strewth...Hold on chaps, it just happens that the TX has four 5V windings on it. I'm sure you could equally as well use 12V. Just needs a bit more 'padding out'
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
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andrew Ivimey
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#23
You can go 1,400 volts, sure but what's wrong with being conventional with 700 volts or so choke loaded - a brick of joy wrapped in gold foil.
What could you do with that! Nirvana.
1400 volts - well really, what could you do with that that is still relatively safe, that can't be done for 960volts or so !
What could you do with that! Nirvana.
1400 volts - well really, what could you do with that that is still relatively safe, that can't be done for 960volts or so !
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Mike H
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#24
It doesn't bother me, just don't let the health and safety people find out about it is all 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
#25
Won't tell them if you dontIt doesn't bother me, just don't let the health and safety people find out about it is all
Darren, still got that 833 going...
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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pre65
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#26
Now that is one amp i would love to see & hear !Nick wrote:
Darren, still got that 833 going...
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)
