555 Switching Compared to Stamp
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Posts: 46,084
I've been researching this ignition coil setup, and found a circuit
where a 555 timer continuously fires an ignition coil using square
waves, switching the current with a large NPN power transistor. My
question is, if the 555 can do it, can the stamp also this this
safely? Or am I better off just going with the MOSFET like some have
suggested?
Thanks,
Bill
where a 555 timer continuously fires an ignition coil using square
waves, switching the current with a large NPN power transistor. My
question is, if the 555 can do it, can the stamp also this this
safely? Or am I better off just going with the MOSFET like some have
suggested?
Thanks,
Bill
Comments
the Stamp -- use the 555. You could, if you need some logic involved in the
project, use the Stamp to control/gate the 555.
-- Jon Williams
-- Parallax
In a message dated 1/29/2003 11:10:48 AM Central Standard Time,
billak@f... writes:
> I've been researching this ignition coil setup, and found a circuit
> where a 555 timer continuously fires an ignition coil using square
> waves, switching the current with a large NPN power transistor. My
> question is, if the 555 can do it, can the stamp also this this
> safely? Or am I better off just going with the MOSFET like some have
> suggested?
>
> Thanks,
>
> Bill
[noparse][[/noparse]Non-text portions of this message have been removed]
but why would you want to?
do you need to control it for some purpose?
norm
>From: "billakay <billak@f...>" <billak@f...>
>Reply-To: basicstamps@yahoogroups.com
>To: basicstamps@yahoogroups.com
>Subject: [noparse][[/noparse]basicstamps] 555 Switching Compared to Stamp
>Date: Wed, 29 Jan 2003 17:09:19 -0000
>
>I've been researching this ignition coil setup, and found a circuit
>where a 555 timer continuously fires an ignition coil using square
>waves, switching the current with a large NPN power transistor. My
>question is, if the 555 can do it, can the stamp also this this
>safely? Or am I better off just going with the MOSFET like some have
>suggested?
>
>Thanks,
>
>Bill
>
>
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>
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only need to fire it at a certain time in the cycle. I suppose I can
also do as someone else suggested, and just use the stamp to turn on
and off the 555. I guess I'll just see what works. I'm just trying
not to blow up my next stamp once I get a new one.
Thanks
Bill
--- In basicstamps@yahoogroups.com, "norman doty" <normdoty@h...>
wrote:
> yes the stamp can do it also.
> but why would you want to?
> do you need to control it for some purpose?
>
> norm
>
>
>
>
>
>
>
> >From: "billakay <billak@f...>" <billak@f...>
> >Reply-To: basicstamps@yahoogroups.com
> >To: basicstamps@yahoogroups.com
> >Subject: [noparse][[/noparse]basicstamps] 555 Switching Compared to Stamp
> >Date: Wed, 29 Jan 2003 17:09:19 -0000
> >
> >I've been researching this ignition coil setup, and found a
circuit
> >where a 555 timer continuously fires an ignition coil using square
> >waves, switching the current with a large NPN power transistor. My
> >question is, if the 555 can do it, can the stamp also this this
> >safely? Or am I better off just going with the MOSFET like some
have
> >suggested?
> >
> >Thanks,
> >
> >Bill
> >
> >
> >To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> >from the same email address that you subscribed. Text in the
Subject and
> >Body of the message will be ignored.
> >
> >
> >Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
>
>
> _________________________________________________________________
> Protect your PC - get McAfee.com VirusScan Online
> http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963
billak@f... writes:
> Yes, I'm attempting to build a small engine control system, and I
> only need to fire it at a certain time in the cycle. I suppose I can
> also do as someone else suggested, and just use the stamp to turn on
> and off the 555. I guess I'll just see what works. I'm just trying
> not to blow up my next stamp once I get a new one.
>
> Thanks
>
> Bill
>
If you are not going to change the ignition timing (always fire at the same
point before TDC) I would not recommend the stamp. It is easy to trigger the
555 based on possible a sensor you will put on the crank shaft.
If you want details on that aspect, write back to this forum.....
[noparse][[/noparse]Non-text portions of this message have been removed]
done a great deal of math, taking into account RPM, engine stroke,
and a few other factors, and it does seem to be possible for this
project to work. (There should be enough time for the stamp to keep
up with the engine and do all of the calculations).
Perhaps the best option would be to have the stamp simply turn on
the 555 with a simple transistor, long enough to have it do say 5 or
10 pulses through the coil, then turn it off. Then the biggest load
on the stamp would be switching the transistor to give the 555
power. Does this make sense?
Thanks,
Bill
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> In a message dated 1/29/2003 4:37:36 PM Pacific Standard Time,
> billak@f... writes:
>
> > Yes, I'm attempting to build a small engine control system, and
I
> > only need to fire it at a certain time in the cycle. I suppose I
can
> > also do as someone else suggested, and just use the stamp to
turn on
> > and off the 555. I guess I'll just see what works. I'm just
trying
> > not to blow up my next stamp once I get a new one.
> >
> > Thanks
> >
> > Bill
> >
>
> If you are not going to change the ignition timing (always fire at
the same
> point before TDC) I would not recommend the stamp. It is easy to
trigger the
> 555 based on possible a sensor you will put on the crank shaft.
>
> If you want details on that aspect, write back to this forum.....
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
billak@f... writes:
> Perhaps the best option would be to have the stamp simply turn on
> the 555 with a simple transistor, long enough to have it do say 5 or
> 10 pulses through the coil, then turn it off. Then the biggest load
> on the stamp would be switching the transistor to give the 555
> power. Does this make sense?
>
> Thanks,
>
> Bill
>
Make perfect sense. I am pretty sure a transistor is not needed to interface
the stamp to the 555.
Connect 10k ohms from pin 4 of the 555 to Vcc.
Connect 0.01 uF cap from pin 4 of the 555 to a stamp output pin.
Make the stamp pin high.
When you want to "fire" the 555, make the stamp pin low then high. No delay
is needed.
example
high 6
low 6 '555 is "fired"
high 6
That's it!!!!!!!!!!!!!!!!!!!
No transistor needed.
[noparse][[/noparse]Non-text portions of this message have been removed]
on the 555 the same as they are in the circuit I am copying, correct?
Bill
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> In a message dated 1/30/2003 8:58:28 AM Pacific Standard Time,
> billak@f... writes:
>
> > Perhaps the best option would be to have the stamp simply turn
on
> > the 555 with a simple transistor, long enough to have it do say
5 or
> > 10 pulses through the coil, then turn it off. Then the biggest
load
> > on the stamp would be switching the transistor to give the 555
> > power. Does this make sense?
> >
> > Thanks,
> >
> > Bill
> >
>
> Make perfect sense. I am pretty sure a transistor is not needed to
interface
> the stamp to the 555.
>
> Connect 10k ohms from pin 4 of the 555 to Vcc.
> Connect 0.01 uF cap from pin 4 of the 555 to a stamp output pin.
> Make the stamp pin high.
> When you want to "fire" the 555, make the stamp pin low then high.
No delay
> is needed.
>
>
> example
>
> high 6
> low 6 '555 is "fired"
> high 6
>
> That's it!!!!!!!!!!!!!!!!!!!
>
> No transistor needed.
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
billak@f... writes:
> Sounds good to me! So just leave the resistors and everything else
> on the 555 the same as they are in the circuit I am copying, correct?
>
> Bill
>
Yes, the circuit I described related to pin 4 it to "fire" the 555.
[noparse][[/noparse]Non-text portions of this message have been removed]