linear regulator with inverted output voltage?
linear regulator with inverted output voltage?
(OP)
Dear Engineers,
Please may i confirm that a linear voltage regulator (as opposed to the switching type) cannot produce an output voltage that is an inverted form of the input voltage (i.e. a linear regulator cannot produce a negative output voltage if its input was a positive voltage).
Having said this, there are, i believe, methods of using additional circuitry with linear voltage regulators such that such voltage inversion can be realised. If any reader has a circuit diagram for such a circuit then i would be most grateful to be told of the relevant web page.
Best Regards.
Please may i confirm that a linear voltage regulator (as opposed to the switching type) cannot produce an output voltage that is an inverted form of the input voltage (i.e. a linear regulator cannot produce a negative output voltage if its input was a positive voltage).
Having said this, there are, i believe, methods of using additional circuitry with linear voltage regulators such that such voltage inversion can be realised. If any reader has a circuit diagram for such a circuit then i would be most grateful to be told of the relevant web page.
Best Regards.





RE: linear regulator with inverted output voltage?
1.) motor-generator
2.) heater--thermoelectric generator
3.) plasma generator -->magnetohydrodinamic generator
Inverting supply is possible only if it converts the electrical energy to some other kind like
Electrical --> mechanical -->electrical or
electrical --> thermal -->electrical or
electrical --> magnetic --> electrical
The last one is the switching regulator which doesn't
work with DC.
Plesae read FAQ240-1032
My WEB: <http://geocities.com/nbucska/>
RE: linear regulator with inverted output voltage?
You need to add a switching circuit to do as you ask. In it's simplest form the circuit is like this;
oscillator -> switch -> inductor -> rectifier -> regulator
If you're switching you might as well use an inverting DC-DC converter circuit that produces a regulated inverted voltage.
RE: linear regulator with inverted output voltage?
Negative voltages are generated from switching regulators and from inverting charge pump regulators.
Switching regulators use a switching voltage into an inductor to store energy that is then released and steered by a diode. You can buy ICs that have most of the functions on a chip - you only need an exteral inductor and fitercap, and sometimes a schottky diode or power MOSFET in addition to a few passive components. These types can be found from National, Linear Tech, Maxim, TI, Micrel, etc.
Charge-pump types use capacitors as the energy storage mechanism to increase or invert the voltage. You can buy these as ICs and generally need only two to four external capacitors. These types can be found at TI, Intersil, and others.
Waveboy, I assume this question comes from the post you made for the GaSFET transistor supply. In that one, It sounds like a 555 is used as a oscillator, then buffered to drive a diode/capacitor ladder to create both a higher positive and negative voltage. This is somewhat similar to the charge-pump type devices. Hex inverter ICs are also used in this manner with one inverter as the oscillator and the remaining 5 inverters paralled to buffer into a diode/cap multiplier arrangement.
RE: linear regulator with inverted output voltage?
RE: linear regulator with inverted output voltage?
The interesting exception is nbukska's #2 (heater - thermoelectric generator).
RE: linear regulator with inverted output voltage?
Also as VE1BLL points out, the thermoelectric generator and photo-electric are DC, which may have an advantage regarding noise generation in some applications (low noise RF circuits for example). The AC solutions are generally much more efficient that the DC ones.
RE: linear regulator with inverted output voltage?
There are a great many schemes to increase voltage or reverse the polarity, but a linear regulator isn't one of them.