Author Topic: Electric Fence Zapper  (Read 110850 times)

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Offline David HK

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Re: Electric Fence Zapper
« Reply #60 on: April 08, 2013, 05:04:46 pm »
Oztules,

Your note above arrived in excellent time for my morning tea and biscuits. My 6.30 am time must be your 8.30 am time.

Everything above studied and noted. Will follow your guidelines. Am doing well on parts  and have all the coil pieces, triacs, diac, and will shop for the toroid this morning. All being well I can put up a few photographs towards the weekend.

Dave

Offline David HK

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Re: Electric Fence Zapper
« Reply #61 on: April 09, 2013, 05:44:53 pm »
Oztules,

There is a problem. I spent a few hours last evening tracing the lay out of the circuit as shown in a PCB photo earlier in this thread.

There is a significant circuit difference with the toroid and possibly the diodes as shown in your hand drawn sketch.

I no longer know which one is correct. Drawing below for reference.

Dave

Offline oztules

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Re: Electric Fence Zapper
« Reply #62 on: April 09, 2013, 11:41:53 pm »
Both the  drawings are in fact wrong.

The circuit board shows the diodes across the switches, which is fair. This will catch the toroid and transformer back EMF, The hand drawn one has the diodes and caps on the transformer side of the toroid,.. works, but does not kill the back emf from the torroid itself, but better to do what the circuit board does... put the freewheels on the switch side of the toroid, and the caps on the transformer side of the toroid.

Circuit board is right, hand drawn will work, your circuit board drawing of the circuit is back to front, you have the diodes where the caps are and visa versa.
The caps are to shape the primary currrent, so need to be on the primary.
the diodes are there for freewheel chop of back emf... so need to be on the switches.



.............oztules
Flinders Island...... Australia

Offline David HK

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Re: Electric Fence Zapper
« Reply #63 on: April 10, 2013, 12:21:00 am »
Oztules,

I've noted the above and changed the capacitors and diodes around. Does this now make the circuit a workable proposition?

Is there anything else that you beady eye may have overlooked?

Dave


Offline madlabs

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Re: Electric Fence Zapper
« Reply #64 on: April 11, 2013, 10:54:22 am »
Re-wound my primary, wound up with 2X 20 turns. If I need to I'll take some turns off the secondary to bring the volts in line. I have the stuff to build the DC power side. I'll figure out a dump load. I've got some OBIT's (oil burner ignition transformers) or NST's (neon sign transformers) that should work.

Oz, thanks a ton for all of the effort and to David for being schematic guy!

Jonathan
Some people are like a Slinky - not really good for anything, but you still can't help but smile when you shove them down the stairs.

Offline oztules

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Re: Electric Fence Zapper
« Reply #65 on: April 11, 2013, 05:03:10 pm »
Just remember Madlabs, the input impedance of the main transformer will dictate the wave form, and the instantaneous power.

The caps discharge into a virtual short circuit with my transformers ( 9-11 turns of 1.8mm wire X 2 is almost zero ohms, and almost zero impedance.

I have tried some normal 240v:12v transformers, they work well for a few minutes until the secondaries fail.

The neon transformer may be ok insulation wise, but the primary may be a  high impedance ( 110v) and the secondary may be .. well ...I can't guess.

Luck with it all.
David has done well, and approaches it with a professional bent.... the same cannot be said of me I'm afraid.



......................oztules
Flinders Island...... Australia

Offline David HK

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Re: Electric Fence Zapper
« Reply #66 on: April 11, 2013, 05:53:56 pm »
Oztules,

Thank goodness you’re back. I thought my incessant quest for detail may have frightened you away. Detail has been part of my everyday life as a staff officer in Hong Kong Police Headquarters until retirement. Miss a point of detail and things can easily go wrong. Get it right and there are gongs for all. Back to business.

I have progressed further and have used my free PCB Schematic and PCB Express software to produce a printed circuit. The layout is provisional until I can get the tails for coils 1, 2 and 3 soldered onto the bobbin pins. Thereafter I can finalize the layout and/or change anything at the last minute.

I am still gathering parts – some are easy and other not so. The hardest is a 50uf 600v capacitor. Hong Kong has plenty of 450v AC 50uf capacitors but higher voltage is difficult. I shall have to pay a visit to the local scrap yards.

The next step is to visit my local ‘lathe man’ and alter the coil winder (ex Hugh Piggott coils) to that I can fit on the ETD 49 bobbin and the same for the main coil unit.

The PCB is straightforward in layout. The very wide tracks are suitable for 6 amps (don’t know what voltage) and I have tried to keep a wide distance between heavy power tracks. The layout is spacious on the basis that removal and replacement of busted parts can be done easily. Hole diameters and the space needed for large components has been altered so that everything fits comfortably. The miniature coils and associated lines shown on the schematic are for circuit checking only, and will be removed later.

If you can spot anything wrong, or suggest an improvement please let me know because there is plenty of time to make changes.

Dave


Offline oztules

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Re: Electric Fence Zapper
« Reply #67 on: April 11, 2013, 11:21:37 pm »
"The hardest is a 50uf 600v capacitor. Hong Kong has plenty of 450v AC 50uf capacitors"

Thats a perfect capacitor to use.... 450v ac has peaks of  1.414* 450= 636v peak. every .01 seconds at 50hz........so the cap is quite happy at <600v DC

...................oztules
Edit, have a good look at your toroidal, and tell me how it works??? It is supposed to be in series with the primary of the transformer... not in series with the diodes.
Change one track from the output of the triacs from where it is, to the other side of the toroid... where the anodes of the diodes are at present.
Change the circuit diagram to reflect this change... this bit has been tricky for you from the looks of it.

I did not see the circuit before, as I usually just look at the recent posts... sometimes the pics come up... sometimes they don't in that format....... ( we did discuss this here: "The circuit board shows the diodes across the switches, which is fair. This will catch the toroid and transformer back EMF, The hand drawn one has the diodes and caps on the transformer side of the toroid,.. works, but does not kill the back emf from the torroid itself, but better to do what the circuit board does... put the freewheels on the switch side of the toroid, and the caps on the transformer side of the toroid."
Flinders Island...... Australia

Offline David HK

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Re: Electric Fence Zapper
« Reply #68 on: April 12, 2013, 03:40:06 am »
Oztules,

Regarding your last note to change a triac track line.

I understand the anode and cathode of a diode – straightforward – but things need to be a little more clear on which triac track to change. At the moment the last schematic shows:-

the top side of the triacs connecting to one side of the toroid and Capacitors C2 and C3, and,

on the bottom side, the triacs go to ground.

Based on the above two sentences, which one needs to go to the anode side of diodes D5 and D6 on the other side of the toroid?

Once you have clarified this I will update a schematic accordingly.

Dave

Offline oztules

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Re: Electric Fence Zapper
« Reply #69 on: April 12, 2013, 07:49:16 am »
The green track from the triac (A1 terminal) goes to the anode of D5 AND 6....not the right side of the toroid
That way the A1 goes through (series with) the toroid to the primary of the output transformer, rather than bypassing it as it is now.


...... oztules
Flinders Island...... Australia

Offline David HK

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Re: Electric Fence Zapper
« Reply #70 on: April 12, 2013, 05:10:46 pm »
Oztules,

Thanks for the above.  The attached schematic now contains your recommended revision regarding the Triacs connecting to the anodes of the diodes.

I expect your bored stiff with looking at this circuit, but would you mind giving it the once over again for correctness.

I have a question concerning the variable resistor. What current does this carry? And, if it’s fairly large, is an off-board VR required? If Yes, I need to enlarge the holes for wire size.

Next question. You mentioned earlier that the toroid should be in the supply line. Is it worth thinking ahead and adding an alternative layout into the PCB so that with the aid of ‘jumpers’ and alternative positions for the toroid, components can be repositioned? The time and space is available to do this, but could you give me a sketch or sufficient written detail to achieve this.

That’s about it for the moment. I look forward to your comments.


Dave

Offline oztules

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Re: Electric Fence Zapper
« Reply #71 on: April 12, 2013, 07:20:23 pm »
"Next question. You mentioned earlier that the toroid should be in the supply line. Is it worth thinking ahead and adding an alternative layout into the PCB so that with the aid of ‘jumpers’ and alternative positions for the toroid, components can be repositioned? The time and space is available to do this, but could you give me a sketch or sufficient written detail to achieve this."

...... No.

It is worth you looking at the PCB layout I used. Note how thick I tried to make the power tracks. These will carry tons and tons of amps for a very very short time. Our losses over these can be quite high.
I tried to use as much copper as i could in this section between capacitor and transformer. Even the to220 triacs have wide pin spacing, so the track down the middle is as thick as I could get.... but also I use well over 1/16the inch or more of solder on all the copper tracks involved with the power lines... and embed copper into it as well.

Notice also, the tabs that go to the transformer and the main capacitor on the non-triac side are next to each other on a large land, your have a thin 3" track, when they could have been right next to each other, and so keep noise and transmission loss to near zero.

In short, I think you would do well to redesign the power tracks to use as much of the board as possible, with as much copper as possible, and keep the two in/ou tabs to the cap and transformer on the non-switched channel next to each other.... or if your cap has 4 pins on it's top, you could route the transformer direct to it, and have no board losses on that arm at least.

Yes it will work fine in it's current form, but if you want to push lots of fence, you need to keep the losses in the toroid only, that way you can control  the losses so that you get performance and life out of the triacs.

Very high currents involved in the primary circuit.


..................oztules
Flinders Island...... Australia

Offline David HK

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Re: Electric Fence Zapper
« Reply #72 on: April 12, 2013, 09:02:30 pm »
Oztules,

You’re an excellent teacher and I hope you can put up with me as a student.

Your notes are fully understood. I have taken the opportunity to draw your circuit layout in AutoCad which is where I picked up the difference in your sketch circuit as opposed to what you actually produced and have shown in photograph form further back in this thread.

Only this morning I was looking at the photographs again and I noticed the splayed legs of the triacs. Likewise, I have noted how you keep the “take off’ tabs close together.

The PCB illustration I have produced has been an interesting interlude and it has helped me understand a lot about the circuit layout.

I shall now put my shoulder to the wheel and learn how to use PCB Express and draw power and ground planes. At the ripe old age of 65 I never seem to stop learning these days.

The prospects of me deploying this kit in earnest are slim, but I am enjoying the technical appreciation of it all so that I can at least fire it up in my back yard. I expect other forumites are following this thread with curiosity if nothing else, and it will be interesting to see if Madlabs manages to electrify Canada or wherever.

Keep in touch and I will be back with a new PCB layout in a day or so.

Dave

Offline oztules

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Re: Electric Fence Zapper
« Reply #73 on: April 13, 2013, 04:47:01 am »
I'm sorry David,

But I never have a circuit of this final thing or anything else I build ( which is plenty).

It is usually a series of disjointed squiggles of bits of the thing, and it takes it shape on the PCB board itself in the computer. I have never used the schematic capture part of protel software.

So I never really have a circuit, and am too lazy and don't need one once i have gotten the board to work as I want it... just a lazy village idiot. Print more boards if I need them, and just use the pcb program to tell me where the bits go... after a few years I have no idea what I have done, nor how I did it. My memory is very porous in this regard, and I really don't care much about it.

It is a shame really as I do lots of projects that may be of interest, but never have the supporting paperwork, as it has gone to heaven by the time I have finished he project, and usually my initial design changes dramatically from start to finish, as I see better ways to do things. I am no Electronics Engineer by a long long way.... but usually get what I need to get going successfully.

Have fun with it... your never too old.



...................oztules..... just another old coote
Flinders Island...... Australia

Offline David HK

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Re: Electric Fence Zapper
« Reply #74 on: April 13, 2013, 05:30:14 am »
Oztules,

Don’t be sorry for anything. I like your hands on style and I think most Forumites are interested in this small project. Chin up and keep going!

You were right! Your PCB design is far superior and quite easy to set up once one has the knack of using the software.

Attached is my first attempt which is less graceful than yours as it lacks the chamfered corners in many places.

A few observations if I may.

I also found it hard to widen the triac legs and have gone as far as I dare in this drawing. It has occurred to me that I can use a series of tube spacers and a long bolt to link all the triac Tabs together and then connect that to the plane containing the toroid and diodes D 5 and D 6.

One item I cannot find in Hong Kong are PCB tab connectors. They are as uncommon as kangaroos swimming between Wilsons Promontory and Flinders Island.

The red lines connecting coils and C1 are temporary for circuit identification.

Any general comments on planes too close to each other or anything else?

Dave