SSLV1.1 builds & fairy tales

[Marra]

Thanks Salas.

 

[niss_man]

hi TeaBag

Can you help me with how to connect the boards to my najda? The najda has one 5 vdc input (2 terminals) so I will connect the 5 v bib section to this. It also has 12v +/Gnd/- though(3 terminals). I am wondering as +12v on bib has 2 terminals(well 4 if you include the sense circuit) and also -12v on bib has 2/4 terminals on bib as well and it seems they are both separate circuits. Can I connect 2 of the outputs of the bib to make a common ground on the 12v side and that way have the 3 outputs +12/gnd/-12 that I need?

Regards

Simon

 

[Salas]

Connect all the 0 sense and 0 force cables from both polarity sections to your GND power input point on your circuit. Connect +F +S to your +12V power input point. Connect -F -S to your -12V power input point. Twist each sense pair of cables as it leaves each regulator.

 

[niss_man]

Connect all the 0 sense and 0 force cables from both polarity sections to your GND power input point on your circuit. Connect +F +S to your +12V power input point. Connect -F -S to your -12V power input point. Twist each sense pair of cables as it leaves each regulator.

Thanks Salas

 

[niss_man]

Connect all the 0 sense and 0 force cables from both polarity sections to your GND power input point on your circuit. Connect +F +S to your +12V power input point. Connect -F -S to your -12V power input point. Twist each sense pair of cables as it leaves each regulator.

I seem to have low voltage when doing it this way it drops to 5.8 when connected to najda. I have 12v +- when connecting to dummy load resistors though. What do you think is wrong. I have dual coil outputs on my transformer. should the 2 wires be connected for the centre tap maybe?

Regards

Simon

 

[Salas]

Is the dummy as strong a demand as the nadja? Maybe you need more current setting? Looks like current limiting now. Dual coils are correct separate for those regs because each one has its own bridge on each pcb section.

 

[niss_man]

the dummy load was tested with both 27r and also 13.5r. So tested at around .45A and and .9A . Reccomended for najda 12+- is .5A

 

[Salas]

If the regs hold at +/- 12V on 13.5R each, then the current limit you set is sufficient and it it must be another kind of problem like oscillation. Lets continue that in the builds thread, upload a picture on how you connect the regs to the + 0 - nadja inputs there.

 

[Salas]

Tech talks moved from the GB thread.

 

[niss_man]

Continuation from GB thread. Another thing Salas, my +ve 12 v was set using 13.5R but the -12v was set using 21r resistors. The reason is the najda documentation says to use .25A minimum for -ve.

Connections I used was S+ and F+ to 12v+
S- and F- to 12v-
The other 4 0v S and F joined and go to GND/0

 

[Salas]

That's correct connections. Make sure the negative reg stands 13.5 R too. They tend to differ for R101 & R201 for same CCS setting. Minimum spec is a tricky thing because there could be start up maximums we don't cover with the now settings.

 

[Salas]

P.S. You should join all zeros at the nadja end, not pre-joined.

 

[niss_man]

I can not fit all 4 wires into terminal hole so I had to pre join at najda end with about a 2cm flylead to najda.

Should both R101 and R201 be the same? or can they be different as I have done?

 

[Salas]

They can be different if surely sufficient for each rail's transient max. If you can't fit all those wires, close locally at the regs connectors F+ to S+, F0 to S0 and so on and so forth for the negative. Make them normal two wire output regs in other words since you can bring them so near to the load. Connect with few wires as if with standard output type regs. So we see if something changes. If not, scope the rails for possible oscillation(s).

 

[niss_man]

I will do more test tommorow. Thanks for your help today.

 

[Salas]

Alright.

 

[niss_man]

Ok. Coverting to 2 wire output regs by joining F+ to S+ etc has fixed it. Now it has correct voltage at the terminals.

Thanks

 

[Salas]

Its one way or the other, avoiding mixed principle connections. That can perplex matters some times. Like when the polarities consume differently, i.e. showing different impedances.

 

[wineds]

Salas is there any way to make two sslv into a tracking +/- power supply?

 

[Salas]

Salas is there any way to make two sslv into a tracking +/- power supply?

There could be a stereo linear pot with a value comparable to your R103 & R203 replacing those. The trimmers could bring the range base voltages together so to ensure voltage tracking. Because its a pot that will be connected in the heart of Vref(s) you should ensure that no interference is picked up by wires. Better use shielded coax, ground the pot's body etc. Haven't tried that, if it brings oscillations, noise, etc. it may well prove just non doable due to side effects.