This bulb will begin to glow when the back EMF reaches about 100V or more.
Impulse rc driver fixer alternative series#
You can also place a small neon indicator bulb (Ne1)in series with a 1k resistor and place this between the low voltage wires to your ignition coil. The MOV chosen must be able to dissipate the power ans have a voltage rating that will cause it to activate before the voltage gets too high for the drive circuit.
Impulse rc driver fixer alternative driver#
In the example shown above, the MOV will short out any spikes coming from the load, but it is also shorting the driver circuits output for the same brief instant. It will stop conducting when the voltage goes low again. These are semiconductor devices which will only begin conducting when the voltage between its terminals exceeds its rated value. The next diagram uses a device known as a MOV ( Metal Oxide Varistor). A compromise must be found that best suits your setup. Generally speaking, a bigger capacitance and smaller resistance will snub more, but also absorb more drive power thefore reducing efficiency. The values used will depend on your drive frequency. The top digram uses a series connected capacitor and resistor.
These are known as dissipative snubbers because the excess energy is disspated as heat or light. These diagrams represent a few possible ways you can snub EMI in an ignition coil driver. There are many ways to reduce EMI and it can often be useful to use various snubbers in different parts of the circuit. Snubbers are a tricky subject, but in general they are used to reduce electromagnetic interference (EMI) or voltage spikes. Without it, it is very likely you will destroy the transistors or driver ICs. If you build an ignition coil driver to make high voltage sparks and arcs, you will need some sort of EMI protection for your circuit.
It also includes an early warning indicator which will show you how severe the back emf is from your load. We sell an ignition coil driver module which has built in protection against most spikes that would damage a driver. When an ignition coil is being driven unloaded (open circuit on the output) there will be significantly increased back emf and risk of damaging the driver circuit. These circuits will work great for driving ignition coils for high voltage but they can be susceptible to damage from inductive spikes. Using this configuration the output is taken from the two coils output terminals, whereas the circuit above uses the output terminal and ground. This means that the output voltages of each coil are out of phase or opposite to each other (when one is positive, the other is negative). Two ignition Coils are connected in parallel but with opposite polarity. This next circuit is designed for a higher powered output. T2 represents two power transistors connected in parallel and mounted on a heatsink. RC1 is used to help suppress high voltage spikes that can destroy the power transistors. If you use a MOSFET or IGBT instead of a bipolar transistor like the 2n3055, you should also add a pulldown resistor of about 10k between the base/gate pin and GND. Further protection methods are outlined lower down this page and in the comments. Ones with higher voltage ratings will be less likely to be damaged by spikes.
Pretty much any power transistor, IGBT or MOSFET can be used in this circuit as long as it is rated for at last 5A and 100V. While these are cheap and high temperature tolerant, they are susceptible to voltage spikes caused by the inductive nature of the load (ignition coil). This driver circuit is based on the commonly used 2n3055 transistor due to it high power switching capability. Click the link to check stock.Ģn3055 Power Transistors or HV MOSFET or IGBTġN4007 will do but preferably a Schottky Diode We have some compact induction coils available for sale for under £20. It is not essential to use two 12V batteries like shown in the circuits shown below, but it will allow you to obtain bigger sparks. Standard ignition coils can be obtained from most car parts stores for around £25.