The simplistic Salas low voltage shunt regulator

[donovas]

sorry, above problem fixed. Q1 gate was not connected...

 

[AndrewT]

It will depend on which voltage (current demand) depletes earlier.

If there is a load on the output then this will deplete the voltage across the Vref string.

If the load is low then the 17Vdc supply could go down quicker via the current through Q5.

 

[donovas]

also what do you think about using zetex 851 in substitute of bc550? i happen to have some on hand and also understand that theyre lower noise than 550

 

[Salas]

Should probably work without oscillation although it has much higher Cob but it remains you see about that in practice.

 

[Vbenonisen]

This has probably been answered a million times before, but what is the output impedance of the SSHV2, and how long can the output wiring be before the performance starts deteriorating? The reason I'm asking is that I have a SSHV2 -15 V supply on my 1541A DAC that I would prefer to move some distance away from the DAC Board if possible (I'm already using a small decoupling capacitor on the chip).

 

[Vbenonisen]

This has probably been answered a million times before, but what is the output impedance of the SSHV2, and how long can the output wiring be before the performance starts deteriorating? The reason I'm asking is that I have a SSHV2 -15 V supply on my 1541A DAC that I would prefer to move some distance away from the DAC Board if possible (I'm already using a small decoupling capacitor on the chip).

The questions is of course regarding the SSLV and NOT SSHV2 (No idea why I wrote that).

 

[Salas]

Its heavily dependent on spare shunt current allowed and if BJT or MOSFET output type.

Near to 1 mΩ in the passband can be typical if with MOSFET output and 200mA spare.

There is no sure max length. It depends on the load and RFI. Takes to scope and see if its all well in a system. If in doubt, use two wire mode not to expose the sense and don't add more than 10mΩ in copper resistance for two wire mode I would say. Heavy gauge wire can help.

 

[merlin el mago]

Salas the BiB powering the Amanero 3.3VDC is gone, I don't know what's happened only heard an explosion and red LED don't shine, any idea where to start to fix the issue?

 

[Salas]

Can't guess with virtually no info. Can only say that a bang usually means hard short or damage in big parts. Like power semis, electrolytic capacitors, bridges.

 

[merlin el mago]

Salas there is a way to measure the semis with a DVM to know if are good or gone?

 

[merlin el mago]

I checked the D306 red LED and shine.

Green LEDs 302A, 302B, 303 & 304 all shine.

All rectifier diodes ar OK.

 

[merlin el mago]

I believe not so big bang like a cap exploited, perhaps I suspect a small semi like: Q303, Q304 & Q305?

 

[merlin el mago]

Visual inspection not show anything exploited.

 

[Salas]

Salas there is a way to measure the semis with a DVM to know if are good or gone?

Quick checks are done with the DMM in diode mode. See there: How to Know if MOSFET is Defective - ElectronicsBeliever

 

[merlin el mago]

IRF9610
0,61VDC
So is OK

Have I to measure same way the MJE15029G?
If yes pin 1 base, pin 2 collector & pin 3 emiter
Connected red probe pin 2 collector & black probe pin 3 emiter
DVM set diode measures out of range .0L

 

[Salas]

How to test a TRANSISTOR with a multimeter PNP or NPN
How to test a TRANSISTOR with a multimeter PNP or NPN MF#63 - YouTube

 

[merlin el mago]

Salas was the load (Amanero exploited)

 

[Salas]

Had bad tantalums in it that shorted? Has burns in some parts that explain the sound of little explosion you heard?

 

[merlin el mago]

Spoked with Domenico (Amanero owner) to know what's the output impedance and he said 50 ohms so I changed the 4th order LP filter made by abraxalito to have 50 ohms in place of 195 ohms, once changed the Amandero exploited, spoked again with Dom and now he said "la scheda non ha il PCB con l'impedenza controllata quindi è possibile che abbia valori differenti": PCB without controlled impedance so can be different values. "Appena posso misuro l'impedenza di più schede per vedere se ci sono differenze notevoli" asap I can measure the impedance in more PCB to see if there is remarkable differences.

 

[rhythmsandy]

can we use BF256 instead of 2sk170 jfet? for the shunt regulator?