Salas hotrodded blue DCB1 build

[gadut]

I'll try another ccs combination to get equal both rails after receiving 15V transformer, i think that the difference is caused by different Vgs, +rail 4.25V and -rail 4.56V but at least now I know the rule of thumbs I have changed BC517 for 3 times, still got several stocks on my drawer. What i shorted in fact was base& collector. BC517 Vbc shows 6.6V, Vbe shows 0.5V. BC550 Vbe 0.8V

 

[Salas]

BC550 Vbe is rather low. Can you measure drop across 2x600R before you do something else?

 

[gadut]

I measure Vdrop accross 2x600R is 2.7V, and before them 11.6V, after them 8.9V

 

[Salas]

That is with the relay in off state?

 

[gadut]

I don't know whether it's off or on state, but after powering up, no relay click. Relay only clicks after i connect BC517 base+collector

 

[Salas]

Looks like there is not enough voltage for the OMRON to engage, or something's wrong with the 550. Do you have a spare 600R to clip with crocodiles across one of the 2X600 so we see what happens?

 

[sonnya]

Salas!

It is the first time i have seen your buffer! I like it a lot!!!!!!!!

 

[Salas]

Thanks.

 

[gadut]

I can't find another 600R, so I try 150R, V on in4002 3.2V, try 47R and V on in4002 4V with both test make relay click. Should I achieve 5V which I can try several Rdrop combinations.

 

[Salas]

So we found the problem.

 

[Salas]

Is 7812 still giving 11.6 after those changes?

 

[Salas]

Keep in mind it needs 2V+ not to drop out, so maybe the chip is dropping out with your now 12V Tx and mains voltage. After 15+15V Tx re-evaluate the 2x600 vs. click.

 

[gadut]

it's still 11.6V after 7812 another request actually, how to increase relay delay time such 2-3 sec after powering up?

 

[Salas]

Time how long it takes now with the 47K and make it bigger to elongate RC time accordingly.

 

[Salas]

What Vbe the 550 shows after the changes?

 

[gadut]

BC550 Vbe is 8.4V with additional 47R or 150R

 

[Salas]

OK it works as a Zener now as it should when collector is hanging on air.

 

[gadut]

Thanks Salas for your great support

 

[Salas]

BC550 Vbe is 8.4V with additional 47R or 150R

Where you got that OMRON? Ebay?

 

[ypaudio]

Merry Christmas to you all

Today I got a new multimeter, and I have checked my 2SK163, the IDSS is arround 8.22mA ~8.34 mA. Surprisingly, I have 4pcs exact 8.24mA. Is it good JFET for DCB1 ?

Sorry for beginner question, I guess the functionality of the relay in Hypnotize board is only for power on delay, is it works for DC protection? What is the benefit of relay circuit in DCB1?
My amplifier have already capacitor 1uF in input section. Do you think it is enough for speaker DC protection without using the relay in DCB1?