The regulator appears to be working just like it is supposed to, from what I understand.
So next I try to run the oscillator closer to its original environment. The only windings of the transformer used are primary and feedback (and an AC voltmeter at heater). The regulator is still driven by a PSU.
With expectations running high, I switch on the power. No oscillation. I vary the input to the regulator, which has a profound effect on the collector current of the driver: It's either in the vicinity of 0.45 amps or around 72 mA. But
it does not oscillate.
Next I pull out Q1484. No change. I use the exact same 47 nF capacitor I used on the breadboard, a 5.6 k\$\Omega\$ resistor and drive it by my PSU, exactly like I did yesterday. The collector current stays around 72 mA (didn't measure explicitly yesterday, but the PSU showed 0.08 A), but
it does not oscillate.
The remaining difference is the 22 volts supply, the inductor (I had only 56 µH), the 47 µF 'lytic. Added my 47 µF from the breadboard, just to make sure (I had had measured Tek's cap and it had shown good). No change.
This is ridiculous. The circuit is now exactly the same as yesterday, where I had rock solid oscillations. I better call it a day.
![Banging Head |O](https://www.eevblog.com/forum/Smileys/default/bangheadonwall.gif)
![](https://i.imgur.com/iTeKbGB.jpg)
With the original fan removed, I also had to create some extra wind - at the current temperatures it seemed very necessary to me. One more hindrance.