The common bug zapper works like this. 110 ac in--transformer changes it to around 5500 volts and charges up the capacitor (s). Bug flies between the grids and the capacitor(s) discharge, killing the bug. Almost all bug zappers fail because the capacitors burn out. The transformer is still good and the grid is still good but capacitors are toast. An automotive coil discharges around 30,000-40,000 volts to the spark plug, without the use of a capacitor unless there is one internal to the coil. (Yes, I know--old vehicles used to use a condensor with the breaker points) Assuming one could address the AC to DC issue, why can't you use an automotive coil in a bug zapper? Is it because a way would have to be found to break the current in the primary windings (collapse the magnetic field)?
Don't they use like a cascade voltage multiplier? A circuit board with diodes and capacitors in one?
'they' If you are asking about the Bug zappers, the ones I have had just have a transformer and one or 2 capacitors. If 2 caps, they are wired in parallel right off the coil with output going straightt to one side of the grid. New style automotive coils I don't know about.
a car ignition coil uses the point opening and closing and the back EMF to generate the high voltage, so using a square wave If you are feeding 12V AC at 60 Hz Sine wave into a car coil, it would work for a while until it burns because its now working all the time. I seriously think it will work for about an hour or two if your lucky ,then fail
I'm thinking of using an inverter (proff's information notwithstanding) or using a little solar collector and 12v dc battery like my fence charger's use. It only runs a few hrs per night.
Wouldn't upping the coil's input from 12V to 110V also up the output from 30kv to 300kv?
All things equal yes assuming the primary to secondary insulation doesn't breakdown (it will).
After seeing Don's last comment, there is no reason you can't use a car coil but the primary coil impedance (resistance) is pretty damn low so you will need a source driving it that can delivery a ton of current. In a car, the battery is an extremely large current source and it's being switched directly into the coil (with points) or being switched with a high current transistor or FET in the module. They are usually fused at 10-15 amps so you can see they are probably using 2-5 amps and fused at 2x that. That's why the modules heat up and need to be bolted to a big heatsink (sound familiar?)
Getting an inverter to supply that current will be the challenge. Also, car coils don't operate down at 60Hz. If you are idling a V6 at 600 rpm, it's firing three times per revolution so that is 1800Hz. Something lower than that will have a very long on-time and the primary will heat up. That's why they add resistors to many of the older coils in line with the points. When the engine is stopped and the points are closed the primary current is huge and the primary winding can be fried. The resistor limits that *on* current. The oscillator is easy and could drive a couple of high current transistors in parallel if someone wanted to do that. A simple bang-bang output.
Now that I think about it, can you find one of the old electronic ignition conversion kits (like Filco)? You can use the oscillator to drive that (slams 0-12V). The input to those kits were pretty high impedance and didn't need a lot of current (which is why the points would last forever.) Maybe you can score an old electric fence setup?
The condenser in the old systems formed an LC oscillator that would continue to ring when the points opened and stretched the HV output to the plug until the points closed again.
[This message has been edited by TK (edited 08-14-2014).]
... why can't you use an automotive coil in a bug zapper? Is it because a way would have to be found to break the current in the primary windings (collapse the magnetic field)?
Yes.
You could rig up something like an old auto-radio vibrator to switch the coil primary (I did exactly that for some of my high school science projects), but it would waste energy and would probably fail pretty quickly due to high-voltage breakdown unless you had a spark gap built into the system. FWIW, this is exactly the way the original Model T Ford ignition system worked.
quote
Originally posted by TK:
If you are idling a V6 at 600 rpm, it's firing three times per revolution so that is 1800Hz.
Better check your math. A V6 at 600 rpm would be only 30 Hz (i.e. 3 * 600 / 60). (600 rpm = 10 rps, 1800 ppm = 30 pps)
The rest I agree with. An automotive (i.e. Kettering) spark coil doesn't act as an ordinary transformer, rather it is used as a switched, double-wound inductor. (A capacitive-discharge ignition system does use the coil as a pulse transformer, but that's not what we're talking about here.)
[This message has been edited by Marvin McInnis (edited 08-14-2014).]
I think it may be easier to just replace the capacitor in the bug zapper. You can buy capacitors from electronics suppliers. And they're usually pretty cheap.
Your in Texas, why ya zapping the bugs ? Just lasso and tame 'em, or if they are really annoying shoot 'em.
I'm with MEM, just shoot-em, they are big enough down there in Texas ! Get the old AK out and get some target practice in, hell at your antiquity or WTF ever the right word is you may need it !
Steve
------------------ Technology is great when it works, and one big pain in the ass when it doesn't
I think it may be easier to just replace the capacitor in the bug zapper. You can buy capacitors from electronics suppliers. And they're usually pretty cheap.
I would, except the zapper in question is an older one, (Galaxy) with 2 wafer type caps in it. One has disintegrated into dust and the other has no writing on it at all. Manufacturer says "we no longer carry that part nor do we have any specs on that unit". It's been a great, all metal bug zapper for several years, and doing a web search reveals I'm not the first person to run into the stonewall from the manufacturer---they want you to just buy one of the newer/cheaper pieces of crap they make today.
... 2 wafer type caps in it. One has disintegrated into dust and the other has no writing on it at all. Manufacturer says "we no longer carry that part nor do we have any specs on that unit".
Just a guess, but I bet two 1 or 2 μf (microfarad), 10,000 volt, non-polarized capacitors would work just fine. YMMV.
Better check your math. A V6 at 600 rpm would be only 30 Hz (i.e. 3 * 600 / 60). (600 rpm = 10 rps, 1800 ppm = 30 pps)
The rest I agree with. An automotive (i.e. Kettering) spark coil doesn't act as an ordinary transformer, rather it is used as a switched, double-wound inductor. (A capacitive-discharge ignition system does use the coil as a pulse transformer, but that's not what we're talking about here.)
Lol, minutes vs seconds. Yes. Thanks for catching that!
The caps on the actual zapper are for RFI suppression to reduce interference with radios and TVs, etc.
[This message has been edited by TK (edited 08-14-2014).]
It's bug season with a vengeance again and my wife is hell bent that I fix this thing so she can sit on the front porch at night... TK: You said:
quote
The caps on the actual zapper are for RFI suppression to reduce interference with radios and TVs, etc.
Does that mean I can get by without the capacitors if I can put up with any RFI? My camera is broken right now, but I took the zapper apart again to make sure, and here's how it is wired (minus the separate circuit for the fluorescent light.) Only one of the capacitors has disintegrated.
The 110 IN is just a plug--no switch. There is another little coil, but it goes to the fluorescent light and it's starter and it's power just tees off the main 110 before the High Voltage zapper coil. No electronics--no circuit board components at all other than those 2 caps.
[This message has been edited by maryjane (edited 04-24-2015).]
So, the zapper actually works well enough to allow you to sit outside after dark? We must have more bugs here than Texas. I have never had much luck with one.
This one will--or did. Last night, you could barely see the porch ceiling fan light for all the bugs, so I need to do something, so we don't have to run the big fan just to keep the bugs away. This one is an 'old school' all metal Flowtron Galaxie unit--probably from the 70s.
[This message has been edited by maryjane (edited 04-24-2015).]
Back to the car coil. Would a cap not be consided potential energy that is released when the bug bridges the cap via the wire mesh? Are you talking about running a coil non stop? If you wanted to go super cheap you can make salt water capacitors. Im just curious if youre wanting to run the coil full time or not as doing so would be a PITA
All things equal yes assuming the primary to secondary insulation doesn't breakdown (it will).
After seeing Don's last comment, there is no reason you can't use a car coil but the primary coil impedance (resistance) is pretty damn low so you will need a source driving it that can delivery a ton of current. In a car, the battery is an extremely large current source and it's being switched directly into the coil (with points) or being switched with a high current transistor or FET in the module. They are usually fused at 10-15 amps so you can see they are probably using 2-5 amps and fused at 2x that. That's why the modules heat up and need to be bolted to a big heatsink (sound familiar?)
Getting an inverter to supply that current will be the challenge. Also, car coils don't operate down at 60Hz. If you are idling a V6 at 600 rpm, it's firing three times per revolution so that is 1800Hz. Something lower than that will have a very long on-time and the primary will heat up. That's why they add resistors to many of the older coils in line with the points. When the engine is stopped and the points are closed the primary current is huge and the primary winding can be fried. The resistor limits that *on* current. The oscillator is easy and could drive a couple of high current transistors in parallel if someone wanted to do that. A simple bang-bang output.
Now that I think about it, can you find one of the old electronic ignition conversion kits (like Filco)? You can use the oscillator to drive that (slams 0-12V). The input to those kits were pretty high impedance and didn't need a lot of current (which is why the points would last forever.) Maybe you can score an old electric fence setup?
The condenser in the old systems formed an LC oscillator that would continue to ring when the points opened and stretched the HV output to the plug until the points closed again.
Word pron.
