Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Old March 16th 19, 02:54 AM posted to sci.electronics.repair
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Default Disconnecting CFL bulb from powered circuit can cause damage?

I have a mosquito trap with a circline 10W UV fluorescent bulb and a fan, the bulb went bad and it proved difficult to get a replacement. Now I would like to run the bulb only at night to extend its life and I tought to add an LDR, some transistors and a relay to run the bulb only at night.

Problem is the same inverter runs the bulb (CFL like circuit) and the fan, and the fan must never stop. The inverter has separate transformers for the bulb and fan but the drive circuit seems shared.

My concern is if I can place the relay in series with one of the four bulb wires to turn it on and off safely. The inverter ran for several months with a blown bulb so it has no problem to run without a load. But can it be damaged if the bulb is disconnected while powered?

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Old March 16th 19, 03:36 AM posted to sci.electronics.repair
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Default Disconnecting CFL bulb from powered circuit can cause damage?

On 16/03/2019 01:54, Jeroni Paul wrote:
I have a mosquito trap with a circline 10W UV fluorescent bulb and a fan, the bulb went bad and it proved difficult to get a replacement. Now I would like to run the bulb only at night to extend its life and I tought to add an LDR, some transistors and a relay to run the bulb only at night.

Problem is the same inverter runs the bulb (CFL like circuit) and the fan, and the fan must never stop. The inverter has separate transformers for the bulb and fan but the drive circuit seems shared.

My concern is if I can place the relay in series with one of the four bulb wires to turn it on and off safely. The inverter ran for several months with a blown bulb so it has no problem to run without a load. But can it be damaged if the bulb is disconnected while powered?


How complex would you like this?

I'd separate things and run the fan from it's own power supply that also
supports a circuit that

1) switches the fan off after the lamp has cooled,
2) doesn't allow the inverter to turn on if the fan is not running

A bit of simple logic, or a micro....

--
Adrian C
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Old March 16th 19, 10:17 AM posted to sci.electronics.repair
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Default Disconnecting CFL bulb from powered circuit can cause damage?

On Saturday, 16 March 2019 01:54:38 UTC, Jeroni Paul wrote:

I have a mosquito trap with a circline 10W UV fluorescent bulb and a fan, the bulb went bad and it proved difficult to get a replacement. Now I would like to run the bulb only at night to extend its life and I tought to add an LDR, some transistors and a relay to run the bulb only at night.

Problem is the same inverter runs the bulb (CFL like circuit) and the fan, and the fan must never stop. The inverter has separate transformers for the bulb and fan but the drive circuit seems shared.

My concern is if I can place the relay in series with one of the four bulb wires to turn it on and off safely. The inverter ran for several months with a blown bulb so it has no problem to run without a load. But can it be damaged if the bulb is disconnected while powered?


a small halogen bulb also works to attract bugs.


NT
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Old March 16th 19, 11:16 PM posted to sci.electronics.repair
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Default Disconnecting CFL bulb from powered circuit can cause damage?

Adrian Caspersz wrote:
How complex would you like this?

I'd separate things and run the fan from it's own power supply that also
supports a circuit that

1) switches the fan off after the lamp has cooled,
2) doesn't allow the inverter to turn on if the fan is not running

A bit of simple logic, or a micro....

--
Adrian C


The fan is not for cooling. It is a mosquito trap and the fan sucks mosquitoes attracted by a chemical compound, heat and UV light. The fan must not stop or the mosquitoes will escape.

I forgot to mention it is a Jata MT8.
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Old Yesterday, 02:46 PM posted to sci.electronics.repair
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Default Disconnecting CFL bulb from powered circuit can cause damage?

On Friday, March 15, 2019 at 9:54:38 PM UTC-4, Jeroni Paul wrote:
I have a mosquito trap with a circline 10W UV fluorescent bulb and a fan, the bulb went bad and it proved difficult to get a replacement. Now I would like to run the bulb only at night to extend its life and I tought to add an LDR, some transistors and a relay to run the bulb only at night.

Problem is the same inverter runs the bulb (CFL like circuit) and the fan, and the fan must never stop. The inverter has separate transformers for the bulb and fan but the drive circuit seems shared.

My concern is if I can place the relay in series with one of the four bulb wires to turn it on and off safely. The inverter ran for several months with a blown bulb so it has no problem to run without a load. But can it be damaged if the bulb is disconnected while powered?



Is there room to add a supply just to power the fan? If so, you can arrange to power down the CFL inverter (even directly at the processing chip which usually has an enable line) when not needed instead of suddenly disconnecting the load. This way, you would probably not even need the relay; use your photocell and transistor to shut down the inverter directly.

I don't know if mechanically switching your lamp on and off will damage the lamp or supply, but my gut instinct is no.

Switching power at the processor IC will be safe for both.


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Old Today, 12:43 PM posted to sci.electronics.repair
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Default Disconnecting CFL bulb from powered circuit can cause damage?

As long as you understand that so-called "mosquito traps" based only on light do not actually attract mosquitoes, you will find that any light will do..

The shocking trap has been demonstrated to attract primarily beneficial insects. From: https://www.mosquito.org/page/faq

Do Bug-Zappers work?
Black light insect electrocution devices (Bug Zappers, etc.) are purchased in huge quantities by homeowners due to their demonstrated ability to attract and kill thousands of insects over a 24 hr. period. One industry representative estimates that over 1.75 million of these devices are purchased annually in the U.S. But do they really control pest insects? Bug zappers do indeed kill some mosquitoes. However, the only two controlled studies conducted to date by independent investigators at the University of Notre Dame showed that mosquitoes comprised merely 4.1% and 6.4% respectively of the daily catch over an entire season. Even more important was the finding in both studies that there was no significant difference in the number of mosquitoes found in yards with or without bug zappers. What is particularly disconcerting, however, is the number of non-pest insects that comprise the vast majority of trap catch. Many of these insects are beneficial predators on other insect pests. They in turn constitute a major part of the diet of many songbirds. Indeed, reduced numbers of moth and beetle prey species have contributed significantly to the decline of songbird populations in many affluent suburbs. Insect electrocution devices undoubtedly bear some responsibility for this phenomenon. Mosquitoes continue to be more attracted to humans than to the devices. One study conducted in homeowners' backyards showed that of the insects killed by these devices, only 0.13% were female mosquitoes. An estimated 71 billion to 350 billion beneficial insects may be killed annually in the United States by these electrocuting devices.

Let your conscience be your guide.

Peter Wieck
Melrose Park, PA
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Old Today, 01:03 PM posted to sci.electronics.repair
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Default Disconnecting CFL bulb from powered circuit can cause damage?

On 18/03/2019 11:43, wrote:
An estimated 71 billion to 350 billion beneficial insects may be
killed annually in the United States by these electrocuting devices.

Let your conscience be your guide.


https://www.youtube.com/watch?v=coGBgkjGQ9g

--
Adrian C


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