Building a symmetrical psu B1 buffer

[Salas]

Originally Posted by MashBill

How many LEDs should I buy to get 2 matched strings of 8? More than 20? 30?

30 will do

[AlanElsdon]

Originally Posted by Salas

30 will do

Salas,

I used your method of checking each LED and then strining them together; however what I did before putting them into the proto Hypnotize board was to stick them in a breadboard and checked the entire string. However I was still using a 9v battery as the source; since mine worked first time with no chatter etc I was happy that each string was correct.

However I did wonder whether I should have used say a 12v battery.

Dealing with the strings as a whole seems to me to be more accurate - provided that the method is correct.

Alan

[AndrewT]

Hi,
two 8LED strings will need 16 LEDs.
There will be a small variation between the Vf of the LEDS, probably <20mV.
What is your tolerance on the total 8LED string voltage?

I suspect you don't need any extra LEDs to get a pair of strings with matching <5mV. But, what matching tolerance does the circuit need? +-20mV or +-50mV or +-100mV?

[Salas]

Originally Posted by AlanElsdon

However I did wonder whether I should have used say a 12v battery.

Dealing with the strings as a whole seems to me to be more accurate - provided that the method is correct.

Alan

If you really want to know the final total Vf don't use more than 3 with a 9V at a time. Jot down, add next 3 to the sum.

[dine1967]

Hi Salas,

I have the Mesmerize board and in the process of collecting parts. I was wondering if I could use the regulated supply from the board to feed a chip based phono pre (vsps)? will it effect the B-1 in any way or Iam better off with a seperate regulated supply for the phono. I think I need to adjust the 68R resistors if I run the phono too.

thanks,
Dinesh

[AndrewT]

If you need only a low current, you can tap off a secondary supply after the main smoothing capacitors, i.e. before the CCS of the regulators.
This will have less effect than tapping off after the regulators.
Even less effect if you tap off before the smoothing capacitors. This is where the relay supply comes from.

[Salas]

It can and it will if you allow for the extra mA and some sinks. Still separate would be optimum, but with equal quality psus. Maybe you can run the other application a bit lower B+ so you can utilize an RC drop filter for it, for some separation.

[JeroenR]

Newbie question (just to be sure).

I have some diodes lying around and I wonder if I can use them.

The relay needs an 1N4001 according to the BOM and I have some 1N4007. Can I use the 1N4007 instead? I checked the datasheet and could not see an objection (a bit overrated, ok).

Instead of the MUR120 I have some Vishay SF4007 and some Schottky SB1100. The Schottky's are rated for 100V, is that too low? The Vishay's look ok, a bit overrated again? I guess the diodes won't affect the sound too much...

Thanks,

Jeroen

[crt]

Originally Posted by JeroenR

Newbie question (just to be sure).

I have some diodes lying around and I wonder if I can use them.

The relay needs an 1N4001 according to the BOM and I have some 1N4007. Can I use the 1N4007 instead? I checked the datasheet and could not see an objection (a bit overrated, ok).

Instead of the MUR120 I have some Vishay SF4007 and some Schottky SB1100. The Schottky's are rated for 100V, is that too low? The Vishay's look ok, a bit overrated again? I guess the diodes won't affect the sound too much...

Thanks,

Jeroen

i think 1N4007 will not make problem
i use 1N4004 for Mezmerize

and for MUR subtitution i think no problem too.
LOW ? i use 1N5819 (only 40 Volt) and until now no problem

[massimo]

The 1N4001 in parallel with the relays coil can be replaced with almost everything.

Use the schottky for low voltage application and keep the very good ex TFK now Vishay SF 4007 soft recovery diodes for higher voltage ps (i.e. tubes) where the schottky can't be used.