N.R.M.R.E. An investigation.

[Grumage]

Dear Zephir.

Thank you for your last post.

Cheers Graham.

[AlienGrey]

What has the above really got to do with Nelsons thread I'm asking myself ! Zephyr ?
           *****   Please! go away and stop filling the thread up with unnecessary irrelevant clutter.  *****

I must say I watched Nelson's video which was nothing much like the original card but thanks anyway as I got to understand what he is doing. I think having a 'radio amateurs license degree' would help explain what's going on here much better and I expect Nelson has really done his homework and has a good memory .
Could it be the whole thing is an exciter output device RFC and Aerial load coil radiant energy transmitter ?


Regards AG

[Zephir]

Pay particular attention to how the circuit operates when it first goes into "berserk mode", because after just tens of seconds, you will never see this again quite the same.  I think the voltages actually damage the electrolytic capacitors

IMO from all circuit schematics follows, that the Darlington TR1/Q1 isn't protected against negative voltage spikes to base (passing through C4 capacitor and R1 trimmer). The PN junction of base electrode must be very narrow for to enable carriers drift and high amplification and therefore its reverse voltage remains limited to only few volts. The diode D2/D5 protects only electrolyte capacitors but not base.

He's a young guy, impatient and eager, with everything pretty much black or white.  I remember those days.

You see - and I wouldn't hurry with replication of Nelson's circuit without its understanding instead, until I wouldn't have lotta spare transistors... You omitted the inconspicuous but substantial collector wire passing the toroid coil in your replica. Without it the circuit cannot run as a parametric oscillator and its increased inductance also protects the transistor against voltage spikes (the toroid serves as a massive ferrite bead on the cable).

The mine and your definitions of impatience and eagerness may therefore differ: I'm quick and impatient - but with cautiousness only.

go away and stop filling the thread up with unnecessary irrelevant clutter

Says the truly right guy... ;-)

[Dog-One]

A couple more items I dug up.  (While hunting for Verpies' totem pole lossless clamp circuit)

[Zephir]

OK - but as I said, Nelson Rocha probably drew his wire through toroid coil for a reason - not just for saving space at his picture..;-)