pulse motor and transistor problems

[jasonspinmaster]

i have a problem with my circuit.
i am using a 12 volt motor bike battery
when i connect up the circuit, .  i am getting a pulse but the transistor is staying on any ideas

[hartiberlin]

Hi ,
try to put a 1 to 10 Kohm resistor from the Basis to Ground ofthe driver transistor.
Then it should work.

[jasonspinmaster]

hi  i have connect up 1k to 10 k resistor from the base off the transistor to ground but the transistor is staying on

[Honk]

Have you measured if the transistor is broken or not?

What is the "low state" voltage output from your "555" driver circuit.
It must go lower than 0.6V or the transistor will conduct.
If the output is higher than 0.6V you could try adding a 330R resistor from the base to ground.

Another thing. A regular 555 IC is to weak to directly feed a powerful but low HFE 2N3055 transistor.
You should switch the bipolar transistor to a low Rdson mosfet. A much better solution.

One last point. Have you measured the frequency coming from the 555?
If it is set to high (>1Khz) you will have problems when using a slow big 2N3055 transistor.
It simply doesn't turn of in time. The only good solution in this case is to use a faster transistor, e.g mosfet.

[jasonspinmaster]

the low state out put of the 555 timer is 0.0v until the sensor is blocked and then it goes up to 12v

i do not know how to messure the frequency ?