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LM555 as a Astable Multivibrator help!!

Hello The basic circuit I am using is at this link:

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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

Reply to
pranthony
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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

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petrus bitbyter

Reply to
petrus bitbyter

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...

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Real Programmers Do things like this.
http://webpages.charter.net/jamie_5
Reply to
Jamie

Reply to
pranthony

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.

Reply to
Jamie

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