Power Your Bug Zapper with Solar: 12V DC to 12V AC Conversion Guide

[NTL2009]

Something like that would do it, but I really doubt you need to go to that extreme. I'd be very surprised if it could not handle lead-acid battery voltages, especially with that dome lamp in series dropping it down a bit.

Or a low-drop-out regulator like this, only ~ 0.1-0.2 V drop-out (that is, it needs ~ 12.1 ~ 12.2 V into maintain 12 V out, will stay at 12V out as the input rises above that minimum) at the currents you need, a battery like that probably won't be blow 12.2 with a decent charge, and the zapper would likely work a little below 12V anyhow:

http://www.mouser.com/Search/ProductDetail.aspx?R=LM2940T-12.0%2fNOPBvirtualkey59500000virtualkey926-LM2940T-12.0NOPB

 

[Phil12]

OK, just rigged it up in series. From the battery + (Red wire) - through the dome bulb - through the 10 ohm resistor - to the zapper. The - (black wire) then comes straight back to the battery/solar panel.

When checking volts, I get the same 13.5V - 13.7V between the + and - sides which would be expected, since I'm in parallel and seeing battery and/or solar panel volts. When I read the + wire from before the dome bulb to after the resister I see less than 1 volt (.97). Does this sound "logical"?

It's been on the "UV LED and zapper" for about an hour now. No smoke, flames, or LED's going out yet. :-)

Thanks!

Phil

 

[NTL2009]

If I follow, you are seeing a drop of ~ 1 V across the combination of 10 Ohm R and dome light, which are in series between the battery and zapper. If so, then your 13.5-13.7 V at the battery would be 12.5-12.7 V at the zapper. That is what you should see if you measure across the leads of the zapper.

That's probably as high as the battery voltage will go - I think you'll be fine.

Did you figure out how to get the zapper on through an off/on cycle of your timer?

 

[Phil12]

The 1 (.97) volts is what I see on the multimeter (set at 20V DC scale) when touching the probes "ahead and behind" of the dome light and resistor. Red Probe > dome light > 10 ohm resistor > Black Probe, all on the same + Red wire, heading for the zapper.

That switch to go from "LED Light only" to "UV and zapper" will be the next challenge. As mentioned, it seems to 'always' come on at 'first power-up' in the "LED Light only" mode. Then the push-button switch must be pressed to turn that off, and turn on the "UV and zapper".

That does seem strange to me, as if I had a string of them and always wanted zappers on, I'd have to walk down the string every evening and push every button? It could be a fatal flaw in the design of the zapper for this experiment. That's not mentioned anywhere in the instructions, etc. ie. "You must push the button to switch over to zapper mode each time they come on. I did see something about the "zapper only works in 'UV mode', not with the other 'LED only' mode." I'll check further and see what I can find though.

Photocell - (dusk to dawn switch) is still in transit, but won't matter much if this thing comes on to "LED Light only" each time it gets power, and the button needs to be pressed. It probably doesn't help too much, but the 2 Red wires on the Left side of the board in photo #1 are both going into that switch. The Red to the right of the board goes down into the light and powers either the 'LED' or the 'UV and zapper'. Not sure which one is which.

Thanks!

Phil

 

[Phil12]

Update: Left the zapper on all night, and about 6 bugs total (2 of them mosquitoes) have gone to the happy hunting ground. That part seems to be A-OK! :-)

Will update again in a day or two on this switch between LED and zapper.

Thanks!

Phil

 

[jim hardy]

Sounds like it's not drawing very much current at all.

Does voltage change when you press the button to turn on UV/Zapper ? Do they come on ?

Can't quite make out part numbers on your picture.

What happens if you press and hold the pushbutton ?
Do UV and zapper come on ? If so you can probably just short the switch, or remove it and twist the wires together. Try a piece of tape to hold it pressed, see if it starts okay.

 

[Manolis]

A couple of points:

I agree that that black device is a bridge rectifier. Sometimes these are specified right on the limit. Running with AC input means that all 4 diodes are sharing the heat dissipation. Running with a DC input means that 2 diodes are dissipating ALL the power resulting from the voltage drop x current so they are dissipating double what they would be with AC. (This matters only if you can feel the device getting hot.)

12 volts RMS will produce 12 x 1.4 = 16.8 volts DC, minus about 2 volts lost through the rectifiers. So 14.8 volts.
12 volts DC will produce 12 minus about 2 volts lost through the rectifiers. So 10 volts. Consequently, I wouldn't recommend adding a resistor or bulb to lose even more voltage. In fact, had it not worked I would have been suggesting linking out the bridge rectifier.

 

[jim hardy]

Consequently, I wouldn't recommend adding a resistor or bulb to lose even more voltage. In fact, had it not worked I would have been suggesting linking out the bridge rectifier.

The purpose of the bulb/resistor is to limit current flow into the device should something inside it latch "on". There's a SMPS on that board to make high voltage for the zapper , i wanted to limit current into the device just to rule out pyrotechnics. Don't know for sure yet whether it uses AC ripple to trigger something .

When he gets ready to button this one up the current limiters can go away.
Their 25 amp limit is probably for fire protection.

I did notice also that the zapper box flap says - "Use ONLY with low voltage outdoor landscape lighting products with power packs that have a maximum output rating of 12 volts, 300 watts per circuit."

The light bulb current limiter is an old technician's trick. Being an old technician i just wanted to not destroy the circuit board.

old jim

 

[Phil12]

Hey guys,

Just wanted to give a quick update on this "experiment". I think I'm going to leave it As Is, without the photocell. The zapper works great, almost too well, as I have to disconnect it and clean it off every day or two. I've put it on the front porch and just leave it on 24/7.

Many mosquitoes have gone to the Happy Hunting grounds, though! :-D

Thanks so much for your time and patience with this 'babe in the woods'!

Phil