Baluns

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Dave the bass
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#16

Post by Dave the bass »

Veroboard?

Handy for little projects like that. You can cut the tracks with either a proper cutting tool or a drill bit if you need to break continuity of the tracks.

Like this...
Image

DTB
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IslandPink
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#17

Post by IslandPink »

I love the smell of Veroboard in the morning .
Smells like ..... Victory !
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pre65
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#18

Post by pre65 »

Using a 30v bench power supply, and making a virtual centre tap with two resistors I get +/- 15v.

Thing is, if I use 100R (as in 6.3v heater circuits) the current in each resistor is 150ma.

Is it OK to go higher to say 1K, and limit the current to 15ma ?
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JamesD
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#19

Post by JamesD »

Yes it is fine to go to 1K.

Conventionally one would use two caps of say 100-220uF or so, value is not critical, and a couple of 4.7k resistors to divide the 30V to +/-15V. With the caps in parallel with the resistors.

The caps act as a current reservoir and allow the use of bigger resistors i.e. less current wasted!

J
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Dave the bass
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#20

Post by Dave the bass »

I'm a-wondering if the load you put across the supply is going to unbalance the virtual CT anyway Phil so it might be a case of AOT (Adjust on Test). I think you'd need to take the centre of the PD to the 0V rail of the rest of the cct to reference the split rail supply to achieve what you're after. I've not tried it myself, it be all pants! :)

DTB
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Nick
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#21

Post by Nick »

There are chips designed to produce stable centre voltages. Can't remember the number off the top of my head.
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pre65
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#22

Post by pre65 »

JamesD wrote:Yes it is fine to go to 1K.

Conventionally one would use two caps of say 100-220uF or so, value is not critical, and a couple of 4.7k resistors to divide the 30V to +/-15V. With the caps in parallel with the resistors.

The caps act as a current reservoir and allow the use of bigger resistors i.e. less current wasted!

J
Like in the PSU bit of this diagram ?

http://www.waynekirkwood.com/forum/php/ ... f=12&t=474
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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pre65
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#23

Post by pre65 »

[quote="Dave the bass" I be all pants! :)

DTB[/quote]

Oh prosperous one. :wink:
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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pre65
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#24

Post by pre65 »

Dave the bass wrote:I'm a-wondering if the load you put across the supply is going to unbalance the virtual CT anyway Phil so it might be a case of AOT (Adjust on Test). I think you'd need to take the centre of the PD to the 0V rail of the rest of the cct to reference the split rail supply to achieve what you're after. I've not tried it myself, it be all pants! :)

DTB
That's the plan prosperous one. :)
The only thing necessary for the triumph of evil is for good men to do nothing.

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#25

Post by JamesD »

yes, just like that.

J
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pre65
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#26

Post by pre65 »

Nick wrote:There are chips designed to produce stable centre voltages. Can't remember the number off the top of my head.
The only chips I have knowledge of are oven chips. :wink: :lol:

For the first iteration the bench PSU will suffice. If it works out as planned, then there will have to be a proper PSU built.
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)
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