Building a symmetrical psu B1 buffer

[KatieandDad]

The only problem that I am having with the Toner Transfer method is that I have whiskers between tracks that I have to get rid of.

The photo etch process, IMHO, is far more accurate.

[Salas]

Originally Posted by KatieandDad

Looking at POST 138 you are using traffic lights to acurately produce the reference voltages - Am I right in this assumption ?

You mean the pictures of the black original boards in post 138 I guess. Yes some combine colors. Try 9.4V total, the old ones had an additional drop of a 10R that boosted the 9V a bit. No sinks low Id build that one. Easy to squeeze in crowded box.

[Salas]

Originally Posted by KatieandDad

I've been busy measuring my collection of LEDs - well the 3mm RED and GREEN ones.
I reckon that the best match that I can get for 9V and 5V4 is as follows.
9V = RED RED RED GREEN GREEN. (1.61+1.62+1.61+2.08+2.08 = 9V0)
5V4 = RED RED GREEN. (1.63+1.63+2.11 = 5V37)
I can then match both strings to within 10mV of each other and the target voltage.
Is that sufficiently accurate ?

How did you measure those? This is the best method to measure near real circuit operating conditions:

[tommy_o]

Hey there, I am just starting to source components and wanted to double check the transformer selection before proceeding. Is an Antek AN-0515 appropriate? Specs read 15V and 50VA, but I can't tell if it is 15+0+15 or not (or if I should be using a different product altogether). Link is here .

Or does anyone know of a more logical transformer choice (lower the price, the better; for someone in USA).

[Marra]

The link says two outputs so it should be 0-15;0-15. You would just need to common the two centre wires to make 15-0-15 to connect to the pcb. 50VA is fine if you want to go down the hotrod line.

[tommy_o]

Originally Posted by Marra

The link says two outputs so it should be 0-15;0-15. You would just need to common the two centre wires to make 15-0-15 to connect to the pcb.

Great, thanks Marra!

[KatieandDad]

Originally Posted by Salas

How did you measure those? This is the best method to measure near real circuit operating conditions:

I used a 5V regulated supply and a series 330R resistor to simulate a 10mA current.

I thought that would be accurate enough.

I've just sourced a pair of 0-15 0-15 50VA toroids. I only need one so I've put the other on Swap-Meet.

[buzzforb]

Any benefir to using v rated parts in dcb1?

[KatieandDad]

Originally Posted by buzzforb

Any benefir to using v rated parts in dcb1?

I've heard of V rated tyres for cars but never V rated components ???

[Salas]

Originally Posted by KatieandDad

I used a 5V regulated supply and a series 330R resistor to simulate a 10mA current.

I thought that would be accurate enough.

Not far.