I know that other countries have other styles of igniters that might be wired differently but I am specifically asking about the US style metal halide ignitors.

1: Output

What is output by one of these? It a high voltage pulse or is it more like a continuous output?

2: Innards

What is inside? Is it just a simple few components or does it have chips and triacs and stuff like that? How is the output achieved?

3: Wattages

What is inside that is different for different wattages?

I have next to no knowledge on this and I would like to know if I could maybe use igniters for other purposes or use other things as ignitors. Just curious. Thanks! 

It it true that the vast majority of North American HID lamp ignitors are of the semiparallel type, meaning that they require ballasts with dedicated taps in order to function properly. Because of that, they will not function properly on a mercury vapor ballast due to the fact that almost all mercury vapor ballasts have no ignitor tap. On rare occasions, there are some HID ignitors that are wired differently that specifically do not use dedicated ignitor taps on specific ballasts. This means that those ignitors can function very well on mercury vapor ballasts. Some ignitors are high voltage 2 wire parallel ignitors and interestingly, Payne-Sparkman manufactured the Ultrasonic superimposed ignitors for the North American market. Additionally, I often see European specification superimposed ignitors being frequently sold in North America for tanning bed applications.

The basic US ignitors tend to use 4 components:
A capacitor, about 47..220nF (depends on the energy required), connected between the lamp end and a "center point" within the ignitor
A SIDAC (a voltage controlled switch - once the voltage across its teminals exceeds certain threshold, then remains ON as long as current is flowing through it), connected between the ballast tap and the "center point"
A resistor with a choke in series, this combination is connected between Neutral and the "center point".

After power ON, when the lamp is not ignited, full ballast OCV is across the lamp. So each half wave the capacitor is getting charged via the resistor. Once the voltage across the capacitor reaches the SIDAC threshold voltage, the sidac turns ON and connects the capacitor to the section between the tap and lamp. This then acts as a primary winding the ballast as a pulse transformer, the secondary is then formed by the whole main secondary of the ballast, so a pulse of the capacitor voltage multiplied by the turns ratio appears there as the ignition pulse for the lamp.
Once the lamp ignites, the arc is limiting the voltage so the circuit is not able to charge the capacitor beyond the SIDAC threshold voltage, so the igniter stop pulsing.

The inductor in series with the charging resistor is there to separate the high voltage pulse from being loaded by that resistor (for the short pulse the inductor can have way higher impedance than the resistor).

The sidac threshold uses to be 100V for the series reactor lamps (the 35..150W low voltage HPS), otherwise it uses to be 200V. It then determines the voltage across the capacitor when the pulse is started.
The turns ratio is then set so it transforms this voltage level leads to the ignition peak voltage required for the given lamp type.


European superimposed ignitors use principally the same operation, they just have the dedicated HV pulse transformer in the ignitor and do not use the ballast winding for stepping up the pulse.
The European semiparallel ignitors however work in a different way.

Another interesting thing to know is that in Japan, pulse start metal halide lighting systems often have ignitors built into the ballast, but in cases where the ignitor is separate from the ballast, the ignitor is often integrated into a dedicated remotely ballasted fixture. I learned about this information from a 1992-1993 Toshiba catalog.

The basic US ignitors tend to use 4 components:…

Thank you so much! This was very helpful. I now realize that repurposing these for other things is near impossible because of the need for a tap on the transformer. Had to look up what a SIDAC was but it is essentially what electronics people like me call a DIAC.
Thanks again!

Terminology is somewhat overlapped. There was a discussion on these some time ago. Usually, diac is a small low-voltage transistor-like 3-layer non-linear device typically in use for triggering SCRs and starting CFL ballasts, while SIDAC is a self-triggering TRIAC meant for generating strong pulses at high voltage itself, like in lamp ignitors, gas boiler ignitors, also used in overvoltage protection circuits etc.

The European semiparallel ignitors however work in a different way.

What is the difference between European and American semi-parallel ignitors?

The basic US ignitors tend to use 4 components:
A capacitor, about 47..220nF (depends on the energy required), connected between the lamp end and a "center point" within the ignitor
A SIDAC (a voltage controlled switch - once the voltage across its teminals exceeds certain threshold, then remains ON as long as current is flowing through it), connected between the ballast tap and the "center point"
A resistor with a choke in series, this combination is connected between Neutral and the "center point".

After power ON, when the lamp is not ignited, full ballast OCV is across the lamp. So each half wave the capacitor is getting charged via the resistor. Once the voltage across the capacitor reaches the SIDAC threshold voltage, the sidac turns ON and connects the capacitor to the section between the tap and lamp. This then acts as a primary winding the ballast as a pulse transformer, the secondary is then formed by the whole main secondary of the ballast, so a pulse of the capacitor voltage multiplied by the turns ratio appears there as the ignition pulse for the lamp.
Once the lamp ignites, the arc is limiting the voltage so the circuit is not able to charge the capacitor beyond the SIDAC threshold voltage, so the igniter stop pulsing.

The inductor in series with the charging resistor is there to separate the high voltage pulse from being loaded by that resistor (for the short pulse the inductor can have way higher impedance than the resistor).

The sidac threshold uses to be 100V for the series reactor lamps (the 35..150W low voltage HPS), otherwise it uses to be 200V. It then determines the voltage across the capacitor when the pulse is started.
The turns ratio is then set so it transforms this voltage level leads to the ignition peak voltage required for the given lamp type.


European superimposed ignitors use principally the same operation, they just have the dedicated HV pulse transformer in the ignitor and do not use the ballast winding for stepping up the pulse.
The European semiparallel ignitors however work in a different way.

A European semiparallel ignitor WILL INSTANTANEOUSLY GO UP IN SMOKE on a North American ballast.

@WorldwideHIDCollectorUSA: Your Philips SI-51 two wires parallel ignitor never damaged by your ballasts, and this ignitor uses the ballast to make pulses, similar to a fluorescent starter.

Thank you so much! This was very helpful. I now realize that repurposing these for other things is near impossible because of the need for a tap on the transformer. Had to look up what a SIDAC was but it is essentially what electronics people like me call a DIAC.
Thanks again!

From the outside view, the main principal difference is, once triggered, the the DIAC will snap the voltage across it by about 5V, so from e.g. 35V trigger voltage to 30V hold voltage.
The SIDAC snaps the voltage back to about 1..3V, so once triggered by e.g. 200V, the voltage drop becomes the 1..3V, so nearly a hard short circuit.
So the 5V difference on DIAC is enough to provide triggering pulse from a capacitor to the triac gate in e.g. dimmers, for the ignitor you need the full capacitor voltage to be dumped to the pulse transformer (either the one within the superimposed type, or the ballast winding tap acting as that pulse transformer).

When speaking about the internal structure:
The deep snapback of the SIDAC needs the more complex triac or thyristor structure (where an NPN+PNP pair is driving each other), very often it is implemented as a pair of voltage triggered reverse conductive thyristors connected antiseries (usually with anodes connected together within the package, cathodes then form the terminals). Really two separate dies.

The shallow snap-back of the DIAC is indeed VCEO type of breakdown of an open base NPN transistor, although the one within DIAC is explicitly designed to work in this way, it is still a kind of "simple" NPN (well, the challenge is not that much to get any gain or so, but to reach precise symmetrical characteristics; I would not be surprised, if someone would use pair of identical components antiseries or antiparallel, as most semiconductor processes lead to physically asymmetrical structures. So using two of them, each for one polarity could be easier than really attempting to convince an inherently asymmetrical structure to behave symmetrically, mainly when more current-robust vertical structures are desired).