Stamp crapped out?
Archiver
Posts: 46,084
Hey guys, I got that injector driver circuit working last night, I
was playing with it all last evening, I started messing with it
tonight, and I could hear the injector clicking for a couple
seconds, like it was working correctly, then it stopped. Now the
program recognizes the stamp as connected, but can't download any
programs to it.
What could have happened? I didn't do anything wrong I don't think,
I was just messing with a circuit I had working just fine last night.
Do they have a warranty on these things?
Bill
was playing with it all last evening, I started messing with it
tonight, and I could hear the injector clicking for a couple
seconds, like it was working correctly, then it stopped. Now the
program recognizes the stamp as connected, but can't download any
programs to it.
What could have happened? I didn't do anything wrong I don't think,
I was just messing with a circuit I had working just fine last night.
Do they have a warranty on these things?
Bill
Comments
billak@f... writes:
> Hey guys, I got that injector driver circuit working last night, I
> was playing with it all last evening, I started messing with it
> tonight, and I could hear the injector clicking for a couple
> seconds, like it was working correctly, then it stopped. Now the
> program recognizes the stamp as connected, but can't download any
> programs to it.
>
> What could have happened? I didn't do anything wrong I don't think,
> I was just messing with a circuit I had working just fine last night.
>
> Do they have a warranty on these things?
>
> Bill
>
Warranty on electronics? I think not......
Did you have any kind of diode connected across your injector (cathode to +12
side) to catch inductive spikes when the injector turns off?
[noparse][[/noparse]Non-text portions of this message have been removed]
stamp even through the transistor?
I guess I'll have to order another one, live and learn I guess...
Bill
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> In a message dated 1/25/2003 4:54:24 PM Pacific Standard Time,
> billak@f... writes:
>
> > Hey guys, I got that injector driver circuit working last night,
I
> > was playing with it all last evening, I started messing with it
> > tonight, and I could hear the injector clicking for a couple
> > seconds, like it was working correctly, then it stopped. Now the
> > program recognizes the stamp as connected, but can't download
any
> > programs to it.
> >
> > What could have happened? I didn't do anything wrong I don't
think,
> > I was just messing with a circuit I had working just fine last
night.
> >
> > Do they have a warranty on these things?
> >
> > Bill
> >
>
> Warranty on electronics? I think not......
>
> Did you have any kind of diode connected across your injector
(cathode to +12
> side) to catch inductive spikes when the injector turns off?
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
it didn't just "Smile out." We've been building them for a long time and we
test everything that goes out the door. That said, we're not perfect. Call
our Tech Support group at 916-624-8333 and they'll help you out.
If you're driving some king of inductive load (coil), you'll want to put a
fly-back suppression diode in the circuit, or better yet, buffer the Stamp so
that it's not directly subjected to it.
-- Jon Williams
-- Parallax
In a message dated 1/25/2003 6:54:21 PM Central Standard Time,
billak@f... writes:
> Hey guys, I got that injector driver circuit working last night, I
> was playing with it all last evening, I started messing with it
> tonight, and I could hear the injector clicking for a couple
> seconds, like it was working correctly, then it stopped. Now the
> program recognizes the stamp as connected, but can't download any
> programs to it.
>
> What could have happened? I didn't do anything wrong I don't think,
> I was just messing with a circuit I had working just fine last night.
>
> Do they have a warranty on these things?
>
> Bill
[noparse][[/noparse]Non-text portions of this message have been removed]
connected across the injector coil, as is often done with relay coils. If
you watch an injector waveform with a scope, you will see that the spike is
allowed to go fairly high -- 60 to 80 volts is common. A zener is often
included in the injector driver to clip the spikes at that level.
If you connect a diode across the injector winding, you will find that the
injector stays open MUCH longer after the driver turns off. Some years ago
I had a "discussion" about this with an acquaintance who had written an
injector theory article which was published in one of the automotive trade
magazines. This spike and injector closing stuff was erroneously explained,
and I ended up cooking up a little experiment to show what happens...
I programmed a PIC (Stamp would have been fine too) to switch a MOSFET which
drove an injector for a specific number of 2mS pulses. Using fuel (er... I
mean non-flammable test fluid) at a constant pressure, I was able to measure
the total injected quantity in a large graduated cylinder with repeatability
better than 1%. The MOSFET was rated for 100 volts or more so it handled
the raw injector spikes just fine. Then I installed a spike suppression
diode across the injector and ran the test again. MUCH more fuel was
collected.... and a correction was eventually published.
So, if you want tight control of your injector, you have to do what the
automotive industry does - let the spike go fairly high, and use a driver
transistor that can handle it.
FYI, unless Parallax has changed their policy "cancelled" Stamps can be
exchanged for a replacement at about 1/2 the cost of a new one.
Randy
www.glitchbuster.com
randyjones@w... writes:
> Automotive injector driver circuits do not use a spike suppression diode
> connected across the injector coil, as is often done with relay coils. If
> you watch an injector waveform with a scope, you will see that the spike is
> allowed to go fairly high -- 60 to 80 volts is common. A zener is often
> included in the injector driver to clip the spikes at that level.
>
> If you connect a diode across the injector winding, you will find that the
> injector stays open MUCH longer after the driver turns off. Some years ago
> I had a "discussion" about this with an acquaintance who had written an
> injector theory article which was published in one of the automotive trade
> magazines. This spike and injector closing stuff was erroneously
> explained,
> and I ended up cooking up a little experiment to show what happens...
>
> I programmed a PIC (Stamp would have been fine too) to switch a MOSFET
> which
> drove an injector for a specific number of 2mS pulses. Using fuel (er... I
> mean non-flammable test fluid) at a constant pressure, I was able to
> measure
> the total injected quantity in a large graduated cylinder with
> repeatability
> better than 1%. The MOSFET was rated for 100 volts or more so it handled
> the raw injector spikes just fine. Then I installed a spike suppression
> diode across the injector and ran the test again. MUCH more fuel was
> collected.... and a correction was eventually published.
>
> So, if you want tight control of your injector, you have to do what the
> automotive industry does - let the spike go fairly high, and use a driver
> transistor that can handle it.
>
Good information.....I often wondered how that situation was handled. ie, a
mosfet that can handle the inductive spike....
[noparse][[/noparse]Non-text portions of this message have been removed]
using to drive that injector?
Bill
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> In a message dated 1/25/2003 8:28:33 PM Pacific Standard Time,
> randyjones@w... writes:
>
> > Automotive injector driver circuits do not use a spike
suppression diode
> > connected across the injector coil, as is often done with relay
coils. If
> > you watch an injector waveform with a scope, you will see that
the spike is
> > allowed to go fairly high -- 60 to 80 volts is common. A zener
is often
> > included in the injector driver to clip the spikes at that level.
> >
> > If you connect a diode across the injector winding, you will
find that the
> > injector stays open MUCH longer after the driver turns off.
Some years ago
> > I had a "discussion" about this with an acquaintance who had
written an
> > injector theory article which was published in one of the
automotive trade
> > magazines. This spike and injector closing stuff was
erroneously
> > explained,
> > and I ended up cooking up a little experiment to show what
happens...
> >
> > I programmed a PIC (Stamp would have been fine too) to switch a
MOSFET
> > which
> > drove an injector for a specific number of 2mS pulses. Using
fuel (er... I
> > mean non-flammable test fluid) at a constant pressure, I was
able to
> > measure
> > the total injected quantity in a large graduated cylinder with
> > repeatability
> > better than 1%. The MOSFET was rated for 100 volts or more so
it handled
> > the raw injector spikes just fine. Then I installed a spike
suppression
> > diode across the injector and ran the test again. MUCH more
fuel was
> > collected.... and a correction was eventually published.
> >
> > So, if you want tight control of your injector, you have to do
what the
> > automotive industry does - let the spike go fairly high, and use
a driver
> > transistor that can handle it.
> >
>
> Good information.....I often wondered how that situation was
handled. ie, a
> mosfet that can handle the inductive spike....
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]