Hey,

So I am trying to figure out the problem onto an electric fence (for cattle, advertised 3J 10kV).

(The main power here is 230v, 50Hz)

Peoples already hepled me figuring what a component was.

So here is a schematic:

(schematics on QUCS: regular_sch.PNG)

So my understanding is:

the left side is supposed to provide the power to the circuit (left of the transistor here, which actually a TRIAC).

So the C3 capacitor (25µF) get charges and could reach up to 650v~(230*sqrt(2)*2)

I know it used to reach about 420v before triggering though.

Here is a simplified version of the triggiring side:

(schematics w/ grouped resistors: simplified_sch.PNG)

So the pulse tranformer and the C3 capicitor (25µF) would provide the voltage divider (1.48M/(1.48M+2.21M)).

(I know right, the voltage divider formula works if the output current is zero but there, I think the final voltage is relevant)

Therefore multiplying the voltage by 0.401 to gives charges to the C2 capacitor (4.7µF).

That would yield a maximum voltage of 260.82v (=650.44v*0.401)

So I replaced the original DIAC by a DB3 which should be about 30v-32v (threshold).

Let's take 30v for the maximum best case.

So the charging ratio would be of 11.5%~(30v/260.82v)

Which according to this website (rc circuit basically charges up to 11.5%) (:http://sim.okawa-denshi.jp/en/CRlowkeisan.htm)

Which would be about 2.1sec to reach the 30v (2.21M+1.48M 4.7µF) (R4+R8 w/ C2)

Then the discharge circuit would be triggered (allowing a current pulse through the pulse tranformer).

Another R-C would be formed when the DB3 diac would conduct (221ohm w/ 4.7µF) (R8 w/ C2)

The datasheet of the triac says (nxp bt139-600e) 1.6v to trigger it.

The discharge ratio would be 96.6%~95%~(=(30-1.6)/30).

The discharge time would be 3.1msec.

Making a cycle 2103msec.

Question:

Did I made an error ? (I think I got a PEKBAC problem, aka I am probably making a very obvious mistake)

Because I measered a 901ms cycle so I suppose I am wrong somehow, and I can't figure why my TRIACs and DIAC keep being fried for some reason...

If you guys want to know what I already did:

http://www.eevblog.com/forum/repair/electric-fence-with-an-unknnown-component/I did some more testing but I am pretty much out of ideas (maybe I need to suppose it is a faulty diode)

Basicaly, I can diagnose the symptom but not the cause, therefore I keep frying components.

Thanks for reading.