Replacing failed powersupplies on qbus PDP-11s

[Gordon JC Pearce MM3YEQ]

On Sun, 2009-02-01 at 16:27 -0800, Chuck Guzis wrote:
> On 2 Feb 2009 at 0:09, Gordon JC Pearce MM3YEQ wrote:
> 
> > I've lost count of the number of people I've spoken to in ##electronics
> > and on forums who have got hopelessly lost and confused by trying to
> > simulate simple electronic circuits.  Just build the damn thing and test
> > it, you'll learn far more! But no, they don't want to do that because
> > apparently "it's a waste of time and money".
> 
> Simulation is an essential part of working with programmable (i.e. 
> SystemC, Verilog or VHDL) devices.  Being able to write a good 
> simulation testbench is probably just as valuable as being able to 
> write the original programming for the device.

Again, that's all very well if you're doing something sufficiently
complex and well-defined.  If you are investigating the effect of
putting what is basically a tuned circuit across the supply to a
non-linear load, where a) it's simple enough to build, and b) it's not
clearly defined enough to model, then you're far better just warming up
the soldering iron and breaking out the 'scope.

Likewise, a lot of people seem to be taught that the only way to
investigate a circuit's behaviour is to simulate it.  When someone shows
me a simulator that can accurately reproduce the behaviour of a simple
twin-T filter under all possible conditions then I'll start to warm to
them.  A circuit that doesn't work properly doesn't sit there Just Plain
Doing Nothing, or producing an odd error message.

Gordon