Help converting simple schematic to 110v

On a sunny day (Fri, 25 Jun 2010 19:18:19 -0400) it happened "Martin Riddle" wrote in :

The light *will* attract humans, but as the cage is *isolated* they will be safe. I have an insect light like that, but with only a 2 x voltage multiplier on 230V, and without the 100uF cap, and it is in a plastic cage with a light in it. You can buy those many places. I could modify it for 1.8kV and add the 100uF, and it would still be safe, but the distance between the wires in the grid would need to be increased. I will not modify it, as it kills any insect the way it is now.

I still have an old HeNe laser supply that runs on 12V DC, I think it has enough kV unloaded, could add some divider and charge a 100uF cap to 350 V too. Hang it high on the ceiling so nobody can get to it?

I mean there has to be a sane limit where protection ends no? But for these too inquisitive, they will get zapped. WTF do I care. What agency do you call if you want to light a match? Can be very dangerous under the wrong circumstances?. And asking idiotic questions like you do would make me call the agency with the people in the white coats.

On a sunny day (Fri, 25 Jun 2010 21:02:44 -0700 (PDT)) it happened MC Haip wrote in :

Yes, that is the idea.

n

=A0 =A0 ...Jim Thompson

=A0 =A0| =A0 =A0mens =A0 =A0 |

=A0 | =A0 =A0 et =A0 =A0 =A0|

=A0|

=A0 =A0 =A0 |

This sounds like a pretty good idea. Seems ebay has quite a few used transformers for sale. Thanks for the idea.

Yet another question....

Can anyone advise whether this circuit is designed for AC or DC... does it matter? Also any thoughts on how many amps this will need?

Thanks.

On a sunny day (Sat, 26 Jun 2010 19:21:18 -0700 (PDT)) it happened Michael wrote in :

The circuit is designed for AC input. That is why I suggested transformer 110 v to 230 V on the input.

Add up all the currents (including any safety bleeder resistor), calculate the number or Watts. Then for a 110 V primary calculate the number of VA for the transformer core, Add some losses. Assume that a shorted condition could persist for a long time if a bugs hangs between the wires.

So if for example you have 1 W dissipation in all resistors together, then perhaps use a 2 VA transformer with a thermal protection. You really only need a very small transformer, because,apart from the bleeder resistor, thing only draws a big current when charging up.

in

at:

Strictly AC only. Total load should be less than 30/1000 of an ampere.

l

ore,

angs between the wires.

Thank you very much for the great explanation. Where I was getting confused was in setting up two transformers in an isolation configuration. I've been able to find many small transformers that convert from 110V AC to 12V DC. I haven't been too successful finding any that convert from 12V DC to 230V AC.

- Michael

n

Thanks very much for the help!

On a sunny day (Sun, 27 Jun 2010 05:37:39 -0700 (PDT)) it happened Michael wrote in :

You do not want DC !!!!!!! Transformers, and this ciruit, only work with AC.

I googled a bit using 'transformer 110 to 230 step up', and found among other things this:

100W is a bit much, but the price seems OK (9$).

Perhaps there be better deals. To many wats is probably no problem, maybe it can be used for other things too. Such a 100W transformer may draw some more current though.

More googling finds this at digikey.com:

about 5 $, 10W, and a split primary. You could perhaps try using it like this (download that datasheet):

---------------------------------- 230 V--- | || ( || ( | || ( ) || |__ out

12V ) || |-------------------- 110V ) || |-- | || ( || ( in || ( || | ----------------------- 0V -----------------

But that does not provide isolation from the mains, but neither does the original circuit.

The way this works is that you put 115 V on one winding, and for the output the other 115 V winding is in series, the voltages add, if you connected them the right way.

But for his circuit isolation is important for added safety. With isolation you might get a shock from one part of your fingertip to another part of your fingertip, if you get it between the two electrodes. Without isolation you might get a shock from your fingertip through your body to ground. Nasty! If he gets two of the digikey transformers you recommended, he could hook them

120v to 12v [ ] 12v to 240v then build the voltage multiplier circuit as described in his original post. Mike Mike

at:

It never ceases to amaze me! How many so called experts who, admitedly seem to know a lot about the theory of everyting, give a whole lot of complex advice about how to build and fix the simplest of electrical/electronic devices without any regard for the practicalities of either the fix or the safety of the outcome.

And it is worst with the simplest of problems because useually the OP is too green to understand the dangers he is being led into.

This current device is a prime case. Even the original 110volt version could be a deathtrap.

John G.

On a sunny day (Sun, 27 Jun 2010 10:18:54 -0500) it happened "amdx" wrote in :

OK:

T1 T2 . _________________ ---------------------------------- | . | | | 115 ) || || ( | ) || _________ || ( 115 in | ___ ) || | | || (

115 V | | || ( ) || |__ 230 V out ~ ----)---- || ( 12 12 ) || | | . | || ( ) || |-- . | ) || |_________| || ( |115 ) || || ( 115 | ) || || ( _____________|____| || || | -----------------------------------

It is likely not needed as the whole thing should be in an isolated cage (say plastic) with openings big enough frop the insects to go through, small enough to stop human fingers.

Of course when he wats to catch bats and the like that could be a problem. hehe

at:

Yep. But consider the positive social aspects of natural selection ;-) ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
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"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

There you go again! :-) MikeK

The capacitances in the cascade may need to be doubled.

The lower voltage supply has to be changed into a voltage doubler, to keep the outputs the same. Depending on the configuration, the capacitor value may need change to keep the impedance and stored energy.

And - as already mentioned - please take care that only the bugs get fried and not the users.

--

Tauno Voipio
tauno voipio (at) iki fi

I'd like to extend a very big thank you to everyone who has taken the time to respond to my original post. I've enjoyed reading every response posted.

Although I'm sure this next question will likely draw some criticism, I'd like to gather opinion on how to calculate a suitable sized grid for this circuit. I suspect wire type, gauge and length are valid considerations and will have a bearing on the size (amps) of transformer required.

Perhaps to start I need to determine the total length of wire in the grid and calculate it's resistance. Add in the resistance of the resistors in the circuit. Calculate amps required based on total resistance of the circuit and grid.

Thoughts?

Circuit:

.

Is there any theoretical limit to these voltage tripler diode capacitor ladders?

Aren't HUGE versions of these used for some big lab stuff?

Huge safety liability aren't they?

For any straight metallic wires, (I explicitly exclude coiled-coil tungsten etc.) their resistance is negligible compared to the effective source impedance of the multiplier chain and the resistance of the bug about to be zapped. For any *reasonably* *thick* wires, their resistance is negligible compared to the dynamic impedance of the diodes, 'flash' capacitor (C7) and bug actually being zapped.

It comes down to durability, and ease of cleaning and of construction. For ease of construction, its nice if they are solderable, and durability requires reasonable thickness. Ease of cleaning requires a linear grille rather than a mesh. Make a brass frame and solder 1.5 mm or 1/16" brass rods through holes in two sides of it separated by approximately 1 wingspan of the target insect. put a 'earthy'* grille behind it offset by 1/2 the wire spacing and spaced by 2/3 the wire spacing from the live grille and another 'earthy' grille in front of double the spacing to cope with outsize bugs. Orient the grilles vertically + raked forward for ease of cleaning.

It MUST be installed in an earthed metal box or non flammable insulating enclosure tested to at least 3KV. It should not only be touchproof, but it should be impossible to insert a standard pencil far enough to reach its 'guts' That's at least 8". You need interlocks at least as good as a Microwave has to disconnect the power and short C7 when the housing is opened.

*'earthy' - an explanation. If any output terminal is hard grounded, this device is truely lethal if anyone (e.g. a child) pokes a long conductive object in there. If on the other hand you use an isolating transformer with 2KV rated insulation to feed the points marked mains 230V and only connect the negative side of C7 via a chain of 2 high voltage 1M resistors to ground or neutral, the possible current from touching ONE terminal is limited to a much safer level.

You wouldn't see me building one except for installation over 10' above the floor in an enclosed space with no access for untrained individuals. (2 consecutive locked doors!)

If you are ever thinking of producing one of these for any place with public access, even by trespass, you'd better work anonymously through a chain of at least three shell companies located in the PRC, North Korea, and Iran respectively!

Note: I have not given the ****ing obvious way of extending that circuit at minimum cost for 120V operation, nor will I ever. You will have to

*REFLECT* upon it yourself . . .

--
Ian Malcolm.   London, ENGLAND.  (NEWSGROUP REPLY PREFERRED)
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