Caps as RF suppression are a common use case, as they are placed across a source, blocking DC shorts, and passing Ac/RF interference to ground... But... In this case, the high voltage flyback from the transistor whacking the transformer on and off is charging the cap up to higher than source voltage. It's either discharged through the bug on the wires, or (safely) bled off by the parallel bleeder resistor... (Whichever happens first... ⚡)
2:46... That is a high voltage storage capacitor. It charges when you press the button. There may also be a shunt resistor across the cap to discharge it once the button is released.
My better half loves her bug zappers, and I've had to repair the rechargable one twice now. The first time it was the battery terminal wire had come loose. The second time, it was the wire going to the "kill grid". So it seems the usual failure mode for these devices is due to poor quality soldering at the factory?
Perhaps they use that IC instead of a MOSFET because it has protections on the gate pin to keep spikes from the transformer from exceeding the dielectric strength.
You’re almost certainly right. That will also make the device less susceptible to being zapped by static during handling. You know how some people hate coof masks? That is nothing compared to my deep, abiding hatred of anti static wrist straps.
Thanks for the circuit reverse engineering. Looks like the wire corroded off, must have been a combination of steel wire and recycled solder form some consumer electronics PCB from the late 60's. Loved the sticker "Not a toy".
I had one of those and I had to change the high vlotage capasitor and when I did I had put one in at 600v by accendent and now the racket vaperize's the bug's
The voltage of the capacitor makes zero difference, except that you need to use one rated for at least as high as the original. However if you increase the capacitance of the capacitor, you will increase the amount of energy stores, which in turn creates a bigger zap.
Hi ..me again :) i watch all your vids and really enjoy them. you're my hero alongside big clive. i have a few of these things how can i 'upgrade' them. ie. get a bit more punch out to the grid wires, from say a 9v battery? thanks again :)
Double the zap if you double the size of the capacitor. Or simply add another one in parallel. You will blow the transformer if you increase the battery voltage.
@@johncoops6897 i see. thanks buddy :D question...if you dont mind, can there be an 'upgrade' that will work so as not to drain the batteries as fast also ? or am i dreaming? thanks again :)
@@Palmit_ - The only upgrade you can do to make batteries last longer is to change the battery holder from 2xAAA to either 2xAA or 4xAAA. The device runs on about 3V, which makes it perfect for LiFePO4 lithium if you rewire the batteries in parallel. ... AAA (original) size cells: AAA Alkaline 850-1200 mAh = 1.3-1.8 Wh AAA Ni-MH 350-1000 mAh = 0.8-1.6 Wh 10440 (AAA) LiFePO4 350mAh about 1.0 Wh ... AA cells are much better: AA Alkaline 1800-2850 mAh = up to 3.9 Wh AA Ni-MH around 2200 mAh = up to 3.4Wh 14500 (AA) LiFePO4 600-1000mAh about 3.2 Wh ... So, just changing from 2 x AAA to 2 x AA with more than double the life, probably triple it since these things pull a lot of power and AAA's fade fast under big loads. ... Ni-MH (Metal Hydride) aren't as powerful, but they are rechargeable. You need good quality cells to get decent life, and because cell voltage is 1.2V performance and the sparks will be less than new Alkalines. However Ni-MH has a pretty flat discharge curve so they won't fade much over their (shorter) operating life. ... LiFePO4 cells have a very flat discharge curve too, staying between 3.2 and 3.0V, so even when "flat" they will have similar sparking power to new Alkalines. The problem is that you need to rewire the battery holder AND add a under-voltage protection IC AND use a special charger. ... For me, the easiest is to replace the 2 x AAA Alkalines with 4 x AA LiFePO4 cells in parallel (ie: 3.2V nominal), then add a TP5100 Charging Module with USB-C port. So, you just plug it in to recharge. The charging module *MUST* also have "Protection" against under-voltage or the zapper will kill the cells the first time that you let the cells drop under about 2.5V (which the zapper will automatically do). ... Such a setup (4xAA LiFePO4) would have about 7-8 times longer run time than a pair of AAA's. But I'll repeat... you must have the correct cell protection because LiFePO4 cells cannot survive being over-charged or over-discharged. You could also fit a small battery voltage display so you can press a button to get approximate state of charge, but there is no harm just recharging every day as LiFePO4 cells can cope with a lot more charge cycles than LiPo etc.
@@Palmit_ - Additional info on 14500 (AA-size) LiFePo4. I use these a lot because our local hardware store sells them as replacement for certain high-end solar lawn lights. I use them as replacements for AA Alkaline, and charge them in a multi-slot charger designed for LiFePo4. What kills them is under-voltage, so I am looking for a better solution for myself. ... For "normal" 3.7V lithium you just buy a
Depends on the strength of the batteries and the value of the HV discharge resistor - usually these range from 1-2kV, sometimes higher for the ones that splurge on a voltage multiplier stage.
![NLE Choppa - Or What ft. 41 (Orchestra Mix) [Official Music Video]](http://i.ytimg.com/vi/biOFASEgSOM/mqdefault.jpg)
I have seen a few videos where people have used these as static grass applicators for model railroading.
Clever.
The capacitor is not to suppress inteference, but to give a zap
This. The capacitor stores enough energy that the insect explodes upon contact
I was gonna say that the capacitor to suppress RF doesn't make sense as they block DC but pass AC lol
Caps as RF suppression are a common use case, as they are placed across a source, blocking DC shorts, and passing Ac/RF interference to ground... But... In this case, the high voltage flyback from the transistor whacking the transformer on and off is charging the cap up to higher than source voltage. It's either discharged through the bug on the wires, or (safely) bled off by the parallel bleeder resistor... (Whichever happens first... ⚡)
Correct - it is definitely a ZAPacitor.
I have one of these. I replaced the cap with a larger value. It really zaps now.
I did the same with mine. Only problem now is actually managing to hit the darned fly without destroying the room.
2:46... That is a high voltage storage capacitor. It charges when you press the button. There may also be a shunt resistor across the cap to discharge it once the button is released.
I like the missing wire to give the bug a chance of escaping :)
Like the wrinkles on the bottom of elephant's feet, to save 50% of the ants they walk over.
British design ! It's got to be sporting old chap ! :)
My better half loves her bug zappers, and I've had to repair the rechargable one twice now.
The first time it was the battery terminal wire had come loose. The second time, it was the wire going to the "kill grid".
So it seems the usual failure mode for these devices is due to poor quality soldering at the factory?
This one is more than a decade old and has been bashed around quite a bit over that time.
I'm surprised it's not more damaged than it is.
This device can be used for building a static grass applicator, for use on dioramas and model railroad scenery. Just a thought 😊
Perhaps they use that IC instead of a MOSFET because it has protections on the gate pin to keep spikes from the transformer from exceeding the dielectric strength.
You’re almost certainly right. That will also make the device less susceptible to being zapped by static during handling.
You know how some people hate coof masks? That is nothing compared to my deep, abiding hatred of anti static wrist straps.
Thanks for the circuit reverse engineering. Looks like the wire corroded off, must have been a combination of steel wire and recycled solder form some consumer electronics PCB from the late 60's. Loved the sticker "Not a toy".
The capacitor stores the charge that inevitably does the zap
nice video as others have said I expect the cap is to charge up and discharge when a creature shorts the wires zapping it 🙂
Time to zap some wasps.
thanks for sharing.
I had one of those and I had to change the high vlotage capasitor and when I did I had put one in at 600v by accendent and now the racket vaperize's the bug's
The voltage of the capacitor makes zero difference, except that you need to use one rated for at least as high as the original. However if you increase the capacitance of the capacitor, you will increase the amount of energy stores, which in turn creates a bigger zap.
Missed opportunity to dramaticly zap yourself to increase the entertainment value of the video. Just look at how many subs Electroboom has! :)
What is the open cct output voltage ??
Show us the rfi generated with and without the capacitor installed.
Hi ..me again :) i watch all your vids and really enjoy them. you're my hero alongside big clive. i have a few of these things how can i 'upgrade' them. ie. get a bit more punch out to the grid wires, from say a 9v battery? thanks again :)
Double the zap if you double the size of the capacitor. Or simply add another one in parallel.
You will blow the transformer if you increase the battery voltage.
@@johncoops6897 i see. thanks buddy :D question...if you dont mind, can there be an 'upgrade' that will work so as not to drain the batteries as fast also ? or am i dreaming? thanks again :)
@@Palmit_ - the batteries in mine last for months. They aren't intended to be switched on continually.
@@Palmit_ - The only upgrade you can do to make batteries last longer is to change the battery holder from 2xAAA to either 2xAA or 4xAAA. The device runs on about 3V, which makes it perfect for LiFePO4 lithium if you rewire the batteries in parallel.
...
AAA (original) size cells:
AAA Alkaline 850-1200 mAh = 1.3-1.8 Wh
AAA Ni-MH 350-1000 mAh = 0.8-1.6 Wh
10440 (AAA) LiFePO4 350mAh about 1.0 Wh
...
AA cells are much better:
AA Alkaline 1800-2850 mAh = up to 3.9 Wh
AA Ni-MH around 2200 mAh = up to 3.4Wh
14500 (AA) LiFePO4 600-1000mAh about 3.2 Wh
...
So, just changing from 2 x AAA to 2 x AA with more than double the life, probably triple it since these things pull a lot of power and AAA's fade fast under big loads.
...
Ni-MH (Metal Hydride) aren't as powerful, but they are rechargeable. You need good quality cells to get decent life, and because cell voltage is 1.2V performance and the sparks will be less than new Alkalines. However Ni-MH has a pretty flat discharge curve so they won't fade much over their (shorter) operating life.
...
LiFePO4 cells have a very flat discharge curve too, staying between 3.2 and 3.0V, so even when "flat" they will have similar sparking power to new Alkalines. The problem is that you need to rewire the battery holder AND add a under-voltage protection IC AND use a special charger.
...
For me, the easiest is to replace the 2 x AAA Alkalines with 4 x AA LiFePO4 cells in parallel (ie: 3.2V nominal), then add a TP5100 Charging Module with USB-C port. So, you just plug it in to recharge. The charging module *MUST* also have "Protection" against under-voltage or the zapper will kill the cells the first time that you let the cells drop under about 2.5V (which the zapper will automatically do).
...
Such a setup (4xAA LiFePO4) would have about 7-8 times longer run time than a pair of AAA's. But I'll repeat... you must have the correct cell protection because LiFePO4 cells cannot survive being over-charged or over-discharged. You could also fit a small battery voltage display so you can press a button to get approximate state of charge, but there is no harm just recharging every day as LiFePO4 cells can cope with a lot more charge cycles than LiPo etc.
@@Palmit_ - Additional info on 14500 (AA-size) LiFePo4. I use these a lot because our local hardware store sells them as replacement for certain high-end solar lawn lights. I use them as replacements for AA Alkaline, and charge them in a multi-slot charger designed for LiFePo4. What kills them is under-voltage, so I am looking for a better solution for myself.
...
For "normal" 3.7V lithium you just buy a
Next time: How to boost a bug zapper :D
Any idea of the output voltage of this?
From memory, they output about 1500V
Depends on the strength of the batteries and the value of the HV discharge resistor - usually these range from 1-2kV, sometimes higher for the ones that splurge on a voltage multiplier stage.
Slow down. How was your first sip of beer? Was it so bad couldn't you say?
What can I say? It was a quick easy video. Not much time for more than a few sips.
I finished the rest of the pint while editing.