Current passing for regulator IC's

[Audioguru]

Transistors and darlingtons have a wide range of base-emitter voltage that also changes as they get warm. The datasheets show a maximum voltage for some of them and a typical voltage for others but the range is so wide that you will need to test the one you use and calculate a resistor for it. Your idea of using a 100mA regulator and 1900mA in the pass transistor makes selecting the transistor and calculating the resistor a nightmare. The circuits I showed use a normal 1A regulator with about 600mA in it and a pass transistor with a few Amps. Then any minimum or maximum transistor will work and calculating the resistor value is easy.

 

[Alec_t]

For me its probably best if i breadboard this

Be aware that the contact strips in most breadboards aren't designed to carry heavy currents.

 

[sureshot]

Transistors and darlingtons have a wide range of base-emitter voltage that also changes as they get warm. The datasheets show a maximum voltage for some of them and a typical voltage for others but the range is so wide that you will need to test the one you use and calculate a resistor for it. Your idea of using a 100mA regulator and 1900mA in the pass transistor makes selecting the transistor and calculating the resistor a nightmare. The circuits I showed use a normal 1A regulator with about 600mA in it and a pass transistor with a few Amps. Then any minimum or maximum transistor will work and calculating the resistor value is easy.

Thanks for your help with this. Yes i can see its quite a tall order to expect that much current from a 100mA linear regulator. If i could keep the current through a 1 Amp 7812 with a small heatsink, that would be doable on the prototype size board i plan using. Say with in 250mA if i can achieve that or close to it. For an output current maximum of 2 Amps. I just get hung up on some of the maths, in practical terms I'm not bad at all putting circuits together from diagram shcematics. Thank you again.

 

[sureshot]

Be aware that the contact strips in most breadboards aren't designed to carry heavy currents.

Yes i know about a 1 Amp or there abouts should be the limit. Although i have made up heavier hook up wire for point to point wiring on breadboards before. It didn't go to bad. And the same with copper strip board. I usually solder up continuous heavy tracks, and double or even treble up wiring between tracks. I've done up to 12 Amps like that before now on euro type fibreglass boards. Thank for your help.

 

[sureshot]

I had no intention locking the thread, and I never mentioned such

I just want you to learn correct terminology, it would be a wise thing to do

and that file you attached is NOT the correct terminology

I'm more than happy to comply with forum rules. I only used the term " Amplified current, because every site I've come across uses this term to explain a low or modest input power to a much higher output power by way of single or multiple pass transistors. But if its the way you term it, then sure.