LM555 as a Astable Multivibrator help!!

[[email protected]]

Hello
The basic circuit I am using is at this link:
http://i9.photobucket.com/albums/a60/phil54/lm555circuit.jpg
The resistors are set at 470k and the caps are .1 uf. This gives me a
10Hz
pulse.

Here is my problem I need help with.I am wanting to use this to pulse
the neg.post of a ignition coil to groundcoil to ground.,( to cut
ignition in and out to add it shifting).Now my problem is this circuit
pulses positive.
I can soldier and put things together but when it comes to designing
something like this I am lost.
Can someone give me some help here.
Thanks

 

[petrus bitbyter]

Hello
The basic circuit I am using is at this link:
http://i9.photobucket.com/albums/a60/phil54/lm555circuit.jpg
The resistors are set at 470k and the caps are .1 uf. This gives me a
10Hz
pulse.

Here is my problem I need help with.I am wanting to use this to pulse
the neg.post of a ignition coil to groundcoil to ground.,( to cut
ignition in and out to add it shifting).Now my problem is this circuit
pulses positive.
I can soldier and put things together but when it comes to designing
something like this I am lost.
Can someone give me some help here.
Thanks

Standard way to connect a coil to an output of a (logic) IC. Values of R, D
an Q depend on information you did not provide. It is not even clear to me
how the coil should be connected so I draw the "standard".

-------+------------Vcc
|
|
|
|
+--+---. ,-
| )|(
| )|(
D - +-' '-
^ |
| |
+----+
|
R___ |/
from 555 --|___|-----| Q
output |>
|
--------------+--------Gnd
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

petrus bitbyter

 

[Jamie]

Hello
The basic circuit I am using is at this link:
http://i9.photobucket.com/albums/a60/phil54/lm555circuit.jpg
The resistors are set at 470k and the caps are .1 uf. This gives me a
10Hz
pulse.

Here is my problem I need help with.I am wanting to use this to pulse
the neg.post of a ignition coil to groundcoil to ground.,( to cut
ignition in and out to add it shifting).Now my problem is this circuit
pulses positive.
I can soldier and put things together but when it comes to designing
something like this I am lost.
Can someone give me some help here.
Thanks

that's good that it does.
use that signal to drive a NPN transistor in common emitter mode.
use a decoupling resistor of course so not to over drive the tranny.
the collector should be on the - side of the coil.
P.S.
you mite want to have a small cap from the - side to common other
wise, you mite be seeing your tranny in semi after life land.
there are other ways like, not allowing the tranny to go into
cut off? etc...

 

[[email protected]]

So Jamie,exuse my ignorance,remember I am a boater not to much of a
electronics wiz.
I use a npn transistor connected to the +vcc of the lm555 with the
collector connected to the neg.post on coil? Any suggestions on a
particular npn transistor that would be heavy enough to handle the
switch to ground?

 

[Jamie]

So Jamie,exuse my ignorance,remember I am a boater not to much of a
electronics wiz.
I use a npn transistor connected to the +vcc of the lm555 with the
collector connected to the neg.post on coil? Any suggestions on a
particular npn transistor that would be heavy enough to handle the
switch to ground?
Jamie wrote:

the + side of the coil should be connected to the Vcc source(12 volts)
the 555 timer output should be driving the base of a 2N3055 type
transistor with a resistor in line of approx. 270 ohms or close to it.
the collector will be on the - side of the coil.
the emitter to the common (Vee)..
and at last . a small cap to the collector and emitter or a
diode which maybe better for time response across the coil connections
with the cathode (line side) on the + side of the coil and anode on the
- side of the coil..
when coils are charged and then released from its charging source,
the back flow energy is many times higher in voltage and in reverse
polarity. the diode will conduct at this point and absorb it to protect the
transistor..
you use a simple 1 amp type diode.