I've been trying to build a circuit based on a timing wheel with a hole that switches on a photo resistor by a LED shining through the timing hole and then producing a high tension spark through an ignition coil.
I've got two parts working.
1. The comparator LM393P that gives correct ON/OFF signal dependent on whether the timing hole is sensed.
2. Spark driven by a N3055 with safety diode across collector/emitter and dissapative snubber across collector and positive rail. The N3055 circuit works with a 4.7K pull up resistor on the base. Strangely enough it oscillates with a continuing spark which is not a bad thing as long as it will switch OFF reliably !!
The 'theory' is that when the LM393P is ON it has an 'open collector' which if connected to the base of the N3055 should earth it and switch off the N3055 and hence the spark.
The problem is when I connect the LM393P output to the N3055 base the two circuits become unstable.
Can anyone help with a circuit to connect the two parts correctly?
Perhaps I should try a simple npn low current transistor between the LM393P out with the transistor's collector connected to the base of the N3055. Is this the next step?
I've got two parts working.
1. The comparator LM393P that gives correct ON/OFF signal dependent on whether the timing hole is sensed.
2. Spark driven by a N3055 with safety diode across collector/emitter and dissapative snubber across collector and positive rail. The N3055 circuit works with a 4.7K pull up resistor on the base. Strangely enough it oscillates with a continuing spark which is not a bad thing as long as it will switch OFF reliably !!
The 'theory' is that when the LM393P is ON it has an 'open collector' which if connected to the base of the N3055 should earth it and switch off the N3055 and hence the spark.
The problem is when I connect the LM393P output to the N3055 base the two circuits become unstable.
Can anyone help with a circuit to connect the two parts correctly?
Perhaps I should try a simple npn low current transistor between the LM393P out with the transistor's collector connected to the base of the N3055. Is this the next step?