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Old 5th November 2012, 12:32 AM   #1
freax is offline freax  Australia
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Default Suggestions for a cheap Stereo Phono tube preamp based upon this power transformer?

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This has been sitting around the house for 7 years or more, after obtaining it from my beloved cousin.

Was wondering if anyone could point me in the right direction for a phono preamp based around this transformer?

The B+ mA rating is known as 100mA: Unknown mA on Gardners mains transformer
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Last edited by freax; 5th November 2012 at 12:44 AM.
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Old 5th November 2012, 02:13 AM   #2
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Thankfully, this is an easy 1.

Build a tweaked RCA setup. I've attached the schematic.

Greinacher double, using Schottky diodes and BIG 'lytics, the 6.3 VAC and follow with a 7812 3 terminal regulator to get a good DC heater supply.

FWCT rectify the 300-0-300 taps, with 1200 PIV Schottky diodes. CRCRC filter the "raw" DC. The drops in the filter resistors are your "friend", in this situation. Use a pair of LR8 regulators to provide isolated 250 VDC to each channel.
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Old 5th November 2012, 08:27 AM   #3
freax is offline freax  Australia
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Sounds good to me, will start looking for some wood to prototype it on.

Could do with some help with the voltage doubler circuit. 2200uF values for the caps in the volt doubler circuit?

Just found this:

DC heating, parallel diodes

Whoa, 2x 10,000uF!?
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Last edited by freax; 5th November 2012 at 08:43 AM.
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