Hi Rod.
--- "rod.badcock" <rod.badcock@...> wrote:

> Rick,
>
> I *have* been hammering the poor little transistor
> used in the FET
> driving circuit (base connected to the PIC), and yes
> this is the one
> that blew. I must have been lucky that the original
> transistor must
> have been 'a good un'

I was thinking the same thing.

> as I didn't realise the
> mistake in adjusting
> the trimpot for a good long time.
>
> So thanks for that Rick; I'll replace the transistor
> with something
> more rugged

If you reset the pot and leave it alone it should not
need an upgraded transistor.

> and look at adjusting the circuit *and
> leaving it*.

Let me say this.

Adjusting the pot is not entirely "forbiden", but a
fair amount of testing went into the setting that it
ships with. Adjustments should be made only by those
who know what they are doing.

If you do crank the pulser up, you will get more power
out, but may drive some components out of their safe
range. If you crank it up too far, you may diminish
the pulses as well.

If you are carefull, you can play with it, but at the
RISK of damaging the circuit or burning it up
(unattended fire?)

I would first set it to "default" as per Richard's
instructions, mark the pot so you can always find
default, and then procede to play with it.

At this point, you know what it can and cannot do.

>
> Having said that the circuit has been great for the
> last few years;

I am thrilled that people like it as much as they do.

It is too bad that it has been banned from the
EZ-board forum. Initially, all I wanted was to be part
of an online cominity and develop a really good
pulser.

> you wouldn't believe the number of batteries that
> have been brought
> from (on a tester showing as) useless back to near
> original
> performance. A friend of mine works in a garage here
> and has kept
> all of us supplied with dead batteries that we now
> all use on solar
> and wind power systems.

Well the good news is that I started work on the
second generation of my pic pulsers yesterday. It is a
way off yet, but it looks like I have commited to
designing it.

Thanks to your playing with the pot, I have realized
that it should have different power settings, so I
decided to make the next generation able to self
adjust based on the condition of the battery.

Rick.

>
> Rod
>
> --- In randrdesulfatorforum@yahoogroups.com, Rick
> <fun_4_me_now20012000@...> wrote:
> >
> > Hi Rod.
> >
> > --- "rod.badcock" <rod.badcock@...> wrote:
> >
> > > Sorry I haven't posted back on this forum
> sooner!
> > >
> > > To answer some questions: the 'amplitude' I was
> > > referring to was the
> > > pulser trimpot - as the coil audible
> oscillations
> > > got louder I had
> > > assumed amplitude.
> >
> > The trim pot is supposed to be set at build time
> and
> > left alone. When you turn it you can operate the
> > pulser WAY outside of it's specs. It is a wonder
> it
> > didn't blow out sooner.
> >
> > >
> > > With regards the fitted 2N3904 I was mystified
> that
> > > after having
> > > worked for years I'm only now getting a problem
> > > (even when replaced
> > > with 2N3904) and caused me to question if that
> was
> > > all that was
> > > going on.
> >
> > The one who's base goes directly to the pic
> through a
> > resistor?
> >
> > That transistor gets hammered. If you crank up the
> > pulser, you will excede it's max ave current and
> cook
> > it.
> >
> > I suggest you replace it with something more
> rugged,
> > and then set the pot to where it was when you
> bought
> > the pulser. Richard Lines can help you with that.
> >
> > The next generation does not even have a pot. It
> is
> > set by fixed resistors.
> >
> > I hope that helps.
> >
> > Rick.
>
>
>


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