I have built this in the Multisim simulator and it works there as desired. Now I have built it on a "lame" breadboard.
Is the upper PNP current mirror correct?
Since the "left" leg behaves opposed to the "right" leg when in working order, the current should follow the left leg, right?
Using Ohm's law: 5V / 100 Ohm = 0.05 ampere, which would impossible to achieve from a 78L05. The probe shows 670 microamperes, albeit having 2.5 volt (via a voltage divider of 100K ) on the base of both NPN transistors. Can the output of the simulator be trusted?
It seems the voltage drop is huge from the upper 5 volt rail to beneath the pair of NPN transistors.
The second current mirror I took from the LM13700 datasheet:
It needed different values over the opamp to achieve the same output as above. It is hugely offset towards the positive power rail, hitting it and chopping a little piece of the the wave. Although the voltages on the tail are similar to upper schematic the difference between the legs is bigger than the schematic above.
I just want to omit the balance trimmer between the legs.
to prevent clicking sounds from "Gates" on Q6 (Q4) and Q3 (Q3) from the upper schematic, I have added a Zener Diode to generate 2.5V + a Trimmer to aim for the 0.6 V bias voltage for the bases of the transistors. Question is now, What type of capacitor would be suited best. Polarized or non Polarized and what value?