Simplest Single rail to Split rail

230

03:50:05

I saw hurz posted a very complex single rail to split rail power supply converter and I thought we should first start from the basics. One of the disadvantages of these kind of circuits is that when you split the rail you also split the voltage two so if you have a 40V tramsformer you can get only 20V and if you want it regulated even less (yes im not forgetting the x1.4 voltage increase from the capacitors but even with them if you tax it out you still wont get 20V at the output). Usually this circuit could be constructed by only a few diodes but the power transistors are for current amplification so you can get more thwn 20-30mA at the output. Another disadvantage id that when you detach one of the loads the other one becomes inert too. To compensate you must short one of the emitters depending on which load you've removed

published 11 years ago

rbrtkurtz

11 years ago

I actually built a setup very similar to this for a TDA2030A based amplifier, except it's regulated at ±15V from a 38V transformer. Of course, I'm sure a lot of setups are very similar to this, since it's basic and common. ;) Nevertheless, good demonstration.

thebugger

11 years ago

Its the ground zero for most split rail supplies. Often they add current limiters protective circuitry and such but depending on the purposrcthey are not needed and only this will suffice.

hamilton1300

11 years ago

I'm wondering, do the bulbs not draw the same current, our is it not available? They are the same and the topography is the same for each side but the negative and positive don't seem to have the same output current.

rbrtkurtz

11 years ago

It's because the MOSFETs aren't matched.

hurz

11 years ago

@rbrtkurtz, yes this is one issue

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