Unusual Bias Method

If you ever do explain it, remember to explain why it was done that way, as well.

Spanish modern? I thought it was more "late shaker" or "early Amish".

As requested, entered into PSpice and simulated....

...Jim Thompson

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To get A-B bias that was reliable in the high temperature realm of a car parked in Phoenix. ...Jim Thompson

Depends. You have to apply l'Hopital's rule to verify. ...Jim Thompson

You are virtually on the money!

See...

From: Jim Thompson Newsgroups: sci.electronics.design Subject: Unusual Bias Method - Simulation Date: Wed, 27 Nov 2013 13:11:00 -0700 Message-ID:

for the simulation (and a readable schematic).

Q8 is just a current mirror operating on R13 to establish the bias current at the zero crossing (your observation that corrections only occur while passing thru the zero crossing are dead-on... except that the Q8 current prevents both off). ...Jim Thompson

Thanks. Interesting circuit, this sort of thing is why I scan headers on SED and read some. The above message ID does not seem to work for me however, is the simulation on your web site?

Regards, Glen

Nevermind, I found it.

You object to my use of the word "infinite" to mean "unboundedly large", and I can't see why. I object to Thompson's assertion that, in a stated situation, PCB trace inductance can blow a 2N7000, because he's plain wrong.

Since he won't defend himself, why don't you demonstrate the mosfet destruction? Spice, math, scope snapshot, whatever.

Except I didn't say that... PCB trace. I said uH's. Thus you yet again prove yourself necessary to lie to hide your ignorance.

Because we don't have to jump thru the hoops you seek to create to divert attention from your incompetence.

Why no comment on the amplifier? Awwwh, geeee! It _doesn't_ oscillate, so you need to start some diversionary tactic. Didn't work did it?

GFY >:-} ...Jim Thompson

The original situation was a 12 volt supply, a 30 mA relay coil, and a trace or wire, the issue being where to place the catch diode. You demonstrated a 25 KV spike, then claimed 1KV, then 150 volts, then 80 volts. As I noted, a trace or a wire is a transmission line, not an inductor.

Post the circuit that makes an 80 volt spike, and we'll see if your assumptions make sense. Maybe JF can help you.

Nah, nah, nah nah, nah nah! "A wire" is not a transmission line, nor is a PCB trace, unless it's over a ground plane.

Why don't you go away quietly now... I've wasted way too much time on dealing with your denigration. Larkin is apparently competing to be more obnoxious than Phyllis >:-}

Maybe you should try to prove my amplifier bias scheme oscillates?... that's what YOU claimed.

I sure wouldn't buy anything from a company whose president denigrates good engineering practice.... even if the company does use chips I designed. If you hate me so much, why don't you take out most of the ECL/PECL/CML in your products? Huh ?>:-} ...Jim Thompson

Excellent, Thanks for that Glen.

OK then... that pretty much does it... Do you use the darlington for biasing (Q1/Q2) because you are turning darlingtons on and off?

George H.

oops.. I mean Q5/Q6... Geo

You said you'd post a Spice model. Do it. You're 0 for 2 now.

The Q5/Q6 Darlington is simply to knock down the base current so that a long R/C time constant dominates. ...Jim Thompson

If you like no inductance in your wiring you can keep your wiring... period >:-} ...Jim Thompson