Power and references

[atferrari]

I am ready to build this circuit for the shown voltages and comsumptions.

+1V and - 1V are just voltage references.

Can anyone comment any eventual flaw?

 

[audioguru]

The voltages are poorly regulated. If you need better regulation then use IC voltage regulators.

 

[MikeMl]

Very complicated (large part count) for what it does. You know that zener+voltage followers have rather poor voltage regulation?

 

[crutschow]

Yes, it would likely be better if you used IC regulators which have better regulation and short circuit protection.

What is the source of your power?

 

[atferrari]

Yes, it would likely be better if you used IC regulators which have better regulation and short circuit protection.

What is the source of your power?

Transformer + diode bridge + filter capacitors.

Yes, I've been thinking of ICs. Maybe two LM317 and two LM337?

Yes, the parts count is too high.

 

[alec_t]

If the +5 and -5 rails were well regulated by ICs then a simple voltage divider string connected betwen them could give the +1 and -1 reference voltages.

 

[atferrari]

If the +5 and -5 rails were well regulated by ICs then a simple voltage divider string connected betwen them could give the +1 and -1 reference voltages.

Problem is that LM7805 / LM7905 cannot be hanging from +32V/-32V.

Independent of the above, I want stable voltage references.

 

[MikeMl]

...I want stable voltage references.

Then why did you use a voltage divider containing diodes to get +-1V?

Can you use an LM431? It is a programmable shunt regulator that intrinsically puts out 1.200V or higher....

How much does the load current change on the +-5V supplies. Min current? Max current?

 

[alec_t]

Problem is that LM7805 / LM7905 cannot be hanging from +32V/-32V.

Instead of using the TIP29/30 to get +5/-5 you could use them as pre-regulators to get, say, +12/-12 then use ICs to get +5/-5 from the +12/-12.

 

[crutschow]

Transformer + diode bridge + filter capacitors.

Yes, I've been thinking of ICs. Maybe two LM317 and two LM337?

Yes, the parts count is too high.

For the input voltage you are showing you should use the LM317HV and LM337HV high voltage versions.

 

[atferrari]

For the input voltage you are showing you should use the LM317HV and LM337HV high voltage versions.

Why not common ones?

From the datasheet (LM117)

Besides replacing fixed regulators, the LM117 is useful in a wide variety of other applications. Since the regulator is "floating" and sees only the input-to-output differential voltage, supplies of several hundred volts can be regulated as long as the maximum input to output differential is not ex-ceeded, i.e., avoid short-circuiting the output.

 

[crutschow]

Why not common ones?

From the datasheet (LM117)

Besides replacing fixed regulators, the LM117 is useful in a wide variety of other applications. Since the regulator is "floating" and sees only the input-to-output differential voltage, supplies of several hundred volts can be regulated as long as the maximum input to output differential is not ex-ceeded, i.e., avoid short-circuiting the output.

That's OK if you can guarantee that you will never once short circuit an output. Remember all it takes is just one momentary short.

Personally I would use the HV devices and not have to worry about zapping them with a short.

 

[atferrari]

From the datasheet

Then why did you use a voltage divider containing diodes to get +-1V?

The datsheets suggests it.


Consumptions are those (steady) values.

 

[atferrari]

That's OK if you can guarantee that you will never once short circuit an output. Remember all it takes is just one momentary short.

Personally I would use the HV devices and not have to worry about zapping them with a short.

Yes, I am really concerned. The HVK was my intention but not available locally.

 

[crutschow]

Yes, I am really concerned. The HVK was my intention but not available locally.

Well you could add a current limit circuit at the input to the regulators such as this, using transistors with sufficient voltage rating. You can use the same design for both the plus and minus sides. Just reverse the direction of the circuit (keeping the current flow direction the same).