Hello guys
This is my first post on this forum
I got an idea of making a dual power supply from a single power supply without using a centre tapped transformer (my c.t trans should be arriving today but while I was waiting thought i'd experiment)
Basically the design revolves around using a potential divider to reference a ground halfway between the + voltage and the actual ground of the single power supply.
If 2 resistors (for example 1k and 1k) are used , then when a current is pulled across one of them then there is a voltage drop and the 'ground' shifts which is impractical.
Now what if we put a pair of transistors instead of the resistors and an op amp which references the voltage divider ground to the new 'ground' and corrects the transistors so that the new ground stays at the voltage divider ground.
I've attached a link to the design that I made in circuitlab.
Well... it works when I try pulling current by putting a low resistor (200Ω) across the new 'ground' and say the Positive rail then there is a very slight shift (a few tens of milivolts) in ground corresponding to half of the voltage droop across the positive and negative rail of the power supply which is completely logical.
The problem is if I try to use this supply with an op amp to drive a speaker or something (at about 1khz ), then the ground goes haywire and just can't keep up which is frustrating because the design looks pretty legit to me (i'm still an amateur) and it is as if the op amp can't keep up which doesnt make sense to me . I mean i'd understand if it was at a few hundred khz or at Mhz , but at a few khz it should work fine no?
Any advice/comment/critisimn or improvment that I can make on the design?
I'd well appreciate it
Thanks
https://www.circuitlab.com/circuit/7qnzpt/single-to-dual-power-supply/
The is also a png of it in the attachments
This is my first post on this forum
I got an idea of making a dual power supply from a single power supply without using a centre tapped transformer (my c.t trans should be arriving today but while I was waiting thought i'd experiment)
Basically the design revolves around using a potential divider to reference a ground halfway between the + voltage and the actual ground of the single power supply.
If 2 resistors (for example 1k and 1k) are used , then when a current is pulled across one of them then there is a voltage drop and the 'ground' shifts which is impractical.
Now what if we put a pair of transistors instead of the resistors and an op amp which references the voltage divider ground to the new 'ground' and corrects the transistors so that the new ground stays at the voltage divider ground.
I've attached a link to the design that I made in circuitlab.
Well... it works when I try pulling current by putting a low resistor (200Ω) across the new 'ground' and say the Positive rail then there is a very slight shift (a few tens of milivolts) in ground corresponding to half of the voltage droop across the positive and negative rail of the power supply which is completely logical.
The problem is if I try to use this supply with an op amp to drive a speaker or something (at about 1khz ), then the ground goes haywire and just can't keep up which is frustrating because the design looks pretty legit to me (i'm still an amateur) and it is as if the op amp can't keep up which doesnt make sense to me . I mean i'd understand if it was at a few hundred khz or at Mhz , but at a few khz it should work fine no?
Any advice/comment/critisimn or improvment that I can make on the design?
I'd well appreciate it
Thanks
https://www.circuitlab.com/circuit/7qnzpt/single-to-dual-power-supply/
The is also a png of it in the attachments