AC Electric Fence Energizer

[Boncuk]

Thanks for pointing out that error vne147.

I redrew the schematic and the layout to the nearest possible as the original layout, having no clue what the SCR's purpose is within the circuit.

I doubt that the transformer is on the output side.

In that case the electric fence would certainly turn out as electocuting device.

I also don't see VR1 and the SCR connected in parallel. [the bottom side of VR1 goes to C4 and the top goes to the SCR.]

Anyway I wouldn't like to build that circuit for own applications.

Boncuk

 

[vne147]

The width of the traces connected the screw terminals are really thick compared to the traces in the rest of the circuit. That indicates to me that the screw terminal side is lower voltage higher current while the other side is higher voltage lower current. It looks like the transformer is used to step up the input voltage. At least that's what it looks like to me. I think one way to figure it out for sure would just be to ask the OP. So talkinggoat, which side is the input and which is the output. Also, are there any markings on the transformer?

 

[meatpie]

I don't think you'd need a fuse going to the fence, especially since it's only rated 250v

 

[Boncuk]

I don't think you'd need a fuse going to the fence, especially since it's only rated 250v

Fuses normally blow according to the current they are rated for.

Besides that 250VAC "supplied" by an electric fence and fused 1A (in the open air, where else?) will certainly fry any creature, may it be an animal or human.

Boncuk

 

[Boncuk]

The width of the traces connected the screw terminals are really thick compared to the traces in the rest of the circuit. That indicates to me that the screw terminal side is lower voltage higher current while the other side is higher voltage lower current. It looks like the transformer is used to step up the input voltage. At least that's what it looks like to me. I think one way to figure it out for sure would just be to ask the OP. So talkinggoat, which side is the input and which is the output. Also, are there any markings on the transformer?

Did you also read the print on the original PCB? "HS 03V-0" "94V-0 Δ" and "E119853". They certainly have a meaning - just don't know which.

 

[schmitt trigger]

THe 94V-0 legend is an UL-flammability rating for the PC board.

 

[talkinggoat]

The black and white wires are the input for 110vac. The transformer is for the fence.

 

[vne147]

Did you also read the print on the original PCB? "HS 03V-0" "94V-0 Δ" and "E119853". They certainly have a meaning - just don't know which.

Yes I did. I did a search for the code on the PCB but didn't turn up anything.

The black and white wires are the input for 110vac. The transformer is for the fence.

OK, now we are getting somewhere. It sounds like meatpie was right. The output is likely lower than 110 VAC or else those ginormeous traces wouldn't be necessary. Right???

Talkingoat, the old man wants to know if there are any marking on the transformer or else it's back to the truck with you!

EDIT: BTW, assuming that we are going to be able to work through the problem and recommend a replacement SCR, how are you going to test it?

 

[tcmtech]

Its a variation on a fairly common line powered capacitive discharge type electric fencer.

The AC line voltage gets doubled by the C2, D1, D2 part of the circuit and charges up C4 using the LED and D4 as the return circuit. Once the voltage in C4 reaches the break over voltage of either SC1 or RV2 it creates a pulse that is stepped up to a much higher voltage with low current by the transformer.

Most likely the SC1 or the RV2 varistor shorted out and are in full conduction mode which is why the LED never goes off.

 

[Hero999]

The question is why use a MOV and an SCR?

Surely doing it the conventional way with an SCR and a DIAC is better?

Anyway I think the OP should modify the circuit to do it the conventional way, at least then he knows it's going to work and be reliable.

 

[meatpie]

The output for an electric fence in normally around 4000-6000volts. The animal is shocked similar to you touching a spark plug wire (although the spark plug is a much bigger shock). It can then travel for miles in a skinny wire without dropping the voltage beyond use.

RV1 and RV2 look like a MOV to me, one of them could be suspect.
Could be the transformer's gone bad.
But I reckon it's the scr that's packed it in. One of the close up photos shows signs of numbering at the bottom, probably painted to hide the number.
Try wiping it over with turps then try petrol. Don't bother with thinners.


I think you will need the right scr for it to operate properly and safely.

Has the unit got a brand and model number by any chance ?

Meatpie.

 

[talkinggoat]

It's a Patriot PG1

Here is a shot of the transformer.

Can anyone come up with a schematic for an ac driven capacitance discharge fencer?

 

[Boncuk]

BTW, assuming that we are going to be able to work through the problem and recommend a replacement SCR, how are you going to test it?

That's an easy question. Have his neighbor "P" over the fence.

I suggest to try a TIC106D first. It has a gate current of 0.2mA. If it triggers too early the output voltage will decrease.

The TIC106M has a gate current of 15mA and is rated 600V for inductive loads.

Attached is the updated schematic.

Boncuk

 

[meatpie]

This ones 1900volts out

 

[Boncuk]

This ones 1900volts out

Probably it is. Who knows the transformer winding ratio?

 

[meatpie]

**broken link removed**

 

[Boncuk]

**broken link removed**

Great! A case for an eye surgeon.

 

[mneary]

Interesting, covers "one acre" of fence. I suppose some people lay the fence flat to the ground ;-)

 

[meatpie]

Probably it is. Who knows the transformer winding ratio?

I'll hazard a guess.....20:1