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6,3 V DC filament supply

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4/25/2000 11:05 AM

6,3 V DC filament supply

Hi there,
I have a question regarding 6,3 V DC filament supplies or the building of thereof. In my preamp, I rectified the 6,3 V AC with two 1N4007 in series and one to ground after the first 1N4007. Then I put a 1000 uF (16V) to ground. The odd thing is that when measuring the 6.3 V DC with my VOM the voltage won´t settle on a constant voltage, but rather fluctuates +/- 0.5 V between 5,9 V and 6.4 V. I dont have a scope, but I guess the voltage has lots of ripple riding on its back. What to do??

Thanks for any input,
Dominik

4/25/2000 12:31 PM

In my preamp, I rectified the 6,3 V AC with two 1N4007 in series and one to ground after the first 1N4007. Then I put a 1000 uF (16V) to ground.
what type of rectifier is this, I don't think I've seen this connection before (or am I missing something). Is the 6.3vac winding center tapped or do you have one side grounded?
Recitfing and filtering 6.3vac should result in a higher voltage than 5.9 to 6.4 volts.
jason

4/25/2000 12:33 PM
A.S	Have you tried a larger cap? If not, try something like 4700uF. It all depends on the current. A.S

4/25/2000 1:02 PM

Diodes such as the 1n400x series are pretty cheep so why not try a bridge rec circuit using four diodes. That should give you about 8v to play with. Depending on the current of the heaters 1000-4700uf should be enough. To regulate down to 6v, a good trick is to take a 7805 or equiv, 5v regulator and two forward biased diodes in the ground connection (anode to IC cathode to ground). This will raise the voltage by 1.4v and give you a stable 6.4v heater supply. I've used similar tricks with 12v regs. and heaters in series.

Hope that idea helps

Chris

4/25/2000 3:05 PM
Don Symes	Please take a look at www.aikenamps.com. Under tech info, then under DIY, there is a circuit to do DC haters that you might compare with.

4/25/2000 5:22 PM

Hey, wait a minute. Where is the D.C. haters? I love D.C. and
I'll fight anybody that says differently!

Cheers,

Steve Slick
Badest D.C. Lover On The Block

4/26/2000 5:03 PM
Dr. Know	The Bad Brains were banned from D.C. so they might have some strong feelings about the place.

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