opamp negative supply from single output power supply

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pager48

Joined Nov 25, 2018
161
Is there a simple method to obtain Vee power from single output positive 12v power supply?

This is to power a Vee side of a tda2030 which prevents using large coupling capacitors and improves audio fidelity since those large capacitors introduce distortions and more power can be output from from using -12v instead of using single 24v supply with coupling capacitors.
 
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DickCappels

Joined Aug 21, 2008
6,534
On the output. No large coupling capacitor and as a bonus you get twice the output voltage across the load. The speaker could connect in place of the transformer windings.
upload_2019-5-20_16-57-29.png
As for your transformer idea, something like the circuit below should work, though you would select a different transformer so you get the voltage you want. Just search the web for DC-DC inverter transformer for more examples.
 

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DickCappels

Joined Aug 21, 2008
6,534
Yes, transformers distort audio signals, simetimes noticeably.

Audio transformers are designed with that in mind. I don't know about audio transformers but suspect that some company makes what you are looking for.
 

Bordodynov

Joined May 20, 2015
2,644
See. The scheme shown below will work at 12 volts. If more current is needed, replace the transistors with lower voltages, but with less resistance, and double the capacitors.
2019-05-20_15-07-14.png
 
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DickCappels

Joined Aug 21, 2008
6,534
This circuit is without transformer or capacitor coupling and needs a tap for ground but its better than using switching regulators or transformer coupling. The transformer in the circuit can be a 1:1 low voltage transformer.

Can a ne555 be configured to drive a low side MOSFET to provide power to the TDA2030 but switching off when voltage on TDA2030 side is reached to specified value?

In the circuit in post #11what is the purpose of C6?
Yes an NE555 is an oscillator. People have used them to make switching power supplies but you would be much better off using a switching regulator chip like the TL494 or even the MC34063.
 

MisterBill2

Joined Jan 23, 2018
6,736
If the power supply is a switch mode package then this concept does not work, but for a transformer supply often another set of rectifier diodes can provide the opposite polarity on some circuits. BUT BEWARE that with a second voltage output the total power capacity has not increased.
 
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