Salas SSLV1.3 UltraBiB shunt regulator

[tiggerkater55]

thanks salas, for your reply, thats the problem, i think, because i need 3.3V for the interface, as far as i know... so it has to be a reflector...



best, horst

 

[Salas]

V1.3 would need careful modification for supporting 3.3V.

 

[bbest]

Don't know, it looks rather tightly integrated to fit external units with some ease. You could try for the output stages power lines only and evaluate.

Thank you for answer!
And it is very interesting: what must be done for adjustment UltraBib for 3.3 or even 1.2 V?

 

[Salas]

To use a TTL level Mosfet for M2 of low Vgs (th) like the one in Reflektor, to use one LED only by shorting the other, to use 5mA IDSS J3 so to have lowest Vgs (off). That is for 3.3V. For 1.2V only the L-Adapter can possibly reach so low.

 

[fedde]

The 1.3 can also power digital with very good results. But it has a 5V bottom adjustment limit as standard.

I use 1.3 with JLsounds USB to i2s converter at 5V with good results. So if has no real benefit to move to Reflector D, right?

 

[Salas]

You are alright. It does the job well enough already.

 

[Flikoman]

For M1 you recommend FQP3P20 or is there any other mosfet?

Regards

 

[Salas]

IRF9610 is a sufficient M1 alternative if to set lower than 1Amp CCS current.

 

[Flikoman]

I need Vout 40V and current up to 100, 150mA for a phono stage. So, IRF9610 it is.

Thanks

 

[ronovar]

What is replacement for BC560C/BC550C becuse this is now obsolete part. Mouser or Farnell does not stock these.

Can we replace with KSA992/KSC1815? (Different pinout)

 

[Salas]

Can we replace with KSA992/KSC1815? (Different pinout)

Probably yes but I haven't used them. Look with the scope that there are no oscillations in the Vout rail. If stable with those transistors, it will be OK. (KSC1845 is the KSA992 complement).

 

[Salas]

*BC550C is still available. For obsoleted BC560C the BC559C or B can be used instead in up to 30V output. BC556B for 31V-45V output.

 

[gaszto]

Hi,


I need some help for troubleshooting. I built an UltraBiB v1.3 minikit positive regulator, I used 9VAC transformer, and I would like using it 5V DC Out. R1 resistor is 4.9Ohm, because my DAC Imax is 26mA. I used 100Ohm load resistor. I started to set the output voltage with the pot. the output voltage was constantly 11.36V independently from the position of the potmeter.
I've installed all fet-s, and transistor to the correct location and orientation, I double checked it. I've also double checked all resistors. Everything looks correct, but it looks like something wrong. Could somebody give me tips where should I start the measurement and the troubleshooting?


Thanks Laszlo

 

[Salas]

See if R1 has voltage drop across it first. How much?

 

[gaszto]

Voltage drops is 0.55V (12.27-11.72)

 

[Salas]

You may measure R1 across its two pins no need to measure each pin across gnd. Anyway 0.55V/4.9R=112mA CCS. So the M1 block works. See Vbe for Q2 & Q3 next.

 

[gaszto]

Do you mean voltage between emitter and base? It is strange Q2 is more stable voltage between emitter and bas is around 200mV but Q3 somethime I measured 200mV but sometimes 2.4V, sometimes I can't read, because always changing.

 

[Salas]

Yes, Vbe. That should be stable. Between 0.5-0.6V DC in this case. Are you sure about Q2 Q3 types are the right PNP ones?

 

[gaszto]

Yes, BC560C comes with minikit. Try to repalce it?

 

[Salas]

Remember its pins are CBE from left to right flat face. You measure between B-E. Unload the output and confirm the load resistor's value. Then measure Vgs for M1 & M2 (3-6V pins 1,3). Yes, replace Q2 and/or Q3 if Vbe is still wrong after those other checks.

Before doing semiconductors replacements lastly check the trimmer also with an Ohm meter between pins 1,3 when the power is off. It should be spanning a big range from zero to near its kΩ value (VR//VRR). It needs to be set very low near zero side for 5V out. Did you turn it down enough?