piezo/ignition coil

[TurboSuper]

Very simple: Make a spark gap with the secondary of the coil. Connect the positive terminal of the battery to one terminal of the primary coil, and connect a lead to the other terminal of the coil BUT NOT TO THE BATTERY.

Then, by lightly tapping that lead to the negative terminal of the battery, you should see a spark. Make sure your cap isn't too far apart.

[FishBoy]

would you mind making a simple diagram, I think I know what you mean but I'm not positive

[TurboSuper]

Yeah, try that. But you won't get a spark at the battery terminal, you'll see it at the terminals of the HV part of the coil.

[jimmy101]

The piezo won't hurt the ignition coil, it can't supply anywhere near enough power to overcome the coils internal resistance and capacitance.

For the same reason, the piezo also won't actually do anything when connected to the coil.

Like others have said, there is no reason to even try it.

The ignition coil really shouldn't care which of its two inputs is connected to the batteries plus and minus, coils are non-polar devices. Using a 12V source you won't hurt the coil if it is hooked up "backwards". Using a 300V photocap might hurt the coil if hooked up backwards.

Make a firm connection between you battery (or charged photocap) to one of the coils inputs. Brush the other wire from the battery across the other input to the coil. You should get sparks between the HV lead and one of the two leads from the battery. Many ignition coils have their inputs marked as + and minus, if your's does then hook up that battery using that polarity. The HV should spark to the minus terminal of the battery.

The best test of the coil is that it produces HV sparks when you brsuh the contact with the wire.

If you really want to test the coil you'll need a volt-ohm meter (VOM). There should be a small resistance of perhaps an ohm or two between the two primer contacts. From the HV to one of the primaries there should be basically zero resistance. From the HV to the other primary contact there should be several ohms resistance, more than between the two primaries.

For a wiring diagram google "auto transformer" or ignition coil. This type of transformer uses one contact as the common for both the coils, which is why there are only three contacts instead of four.

Turbo's description is spot on, but you might indeed see small sparks at the battery terminal. (They are "contact" sparks instead of HV sparks.)

[jimmy101]

waffles
double post

[Insomniac]

Mark,
If you hook a battery or other energy source up to the coil the wrong way (with the positive lead hooked up where the negative should be, etc.), you'll destroy the coil. Or at least, that's what happened to me every time.

I wonder why that happens... As I understand it, it shouldn't matter what polarity you use. Hopefully somone with more experience in ignition coils can explain it.

[mark.f]

I've never had that happen, nor has my friend (and he has used tons more ignition coils than me). We just hook the leads up to the primary in any polarity.

[TurboSuper]

Mabye they put a rectifier in some of them for whatever reason